The Mystery Engine
As a Politician said,
won't know what's in it 'til we complete it.
Yesterday, while fiddling around in the shop, I was attracted to a 4"
piece of 2" diameter bar stock. The word "CRANKSHAFT"
popped into my mind so I headed for the bench when I tripped over the
gray cast iron I made the head for the 30-60 out of. Both pieces
on the bench. While doodling on a piece of scratch paper, I
that I'd bought a set of 2:1 miter gears at Zolfo Springs so I added
them to the
The raw materials and sketch.
shape of the 6" long X 4" tall X 2" thick hunk
of cast iron shown has a hopper cooled engine block inside of it.
gotta do is remove all the unnecessary metal. I now have a sketch
shows a single-flywheel engine with a sideshaft. I have a hunk of
thick steel I may have the flywheel waterjet cut out of. So far,
I have no
idea what the valve arrangement will be. Hopefully, something
will come to mind. Hit and miss governing, probably.
Starting on the crankshaft.
facing the piece of bar stock and putting centers in both
ends, I turned the long main to 1.010". Then it was flipped and
short main was turned to the same diameter. The finished diameter
1.000" but I didn't want to take the chance of dinging up one of the
journals in the rest of the process.
the mains done, I dug out the offsets I used to turn the
crankshaft of the 30-60, which has the same main bearing journal
I deeply center punched them at 0.5625" from the centers of the mains
give a stroke of 1.125".
Offset in place, preparing to turn crank throw.
setup you see above for turning the rod journal isn't exactly
what I ended-up using. The offsets were fine but I had to grind a
thin tool that could reach all the way to the 0.8125" finish diameter
the crankpin. That took a while and several experimental tool
shapes to get it done.
Crankshaft nearly done.
I ended-up with looked like a wierd cutoff tool made of a
3/8" tool bit. I ground it to about 0.100" wide and, to minimize
chatter, I ground a groove in the center of the cutting edge that made
it into a
two pointed tool. This seemed to cut better than anything else I
tried. The last 0.0005" was taken off with a fine file and emery
End of crankshaft bored for gear.
crank gear was next. The diameter of the large portion
of the small gear shaft is 0.622". I cut the gear shaft down to
0.375" from the thrust face. The end of the crankshaft was
0.500" diameter to a depth of 0.400", then bored to 0.623(-) and the
gear was pressed into the crankshaft.
Gear pressed into crankshaft and sideshaft laid-up for a look-see.
The only remaining thing to do to the
crankshaft is to mill a keyway for a gib key for the flywheel.
I think the bore will
the range of 1" to 1.250" or so, depending on what I've got to make
the piston out of and how long the rod can be, etc. I think I can
block out with the bandsaw after I've milled the outsides of the hunk
flat and square. Boring the cylinder may involve making a boring
run between centers in the lathe and clamping the block to the carriage.
bronze and I'll do what's worked fine in the past for a wrist pin - a
polished dowel pin. This
looks like it will be a minimal CAD project. I may lay out the
crank, piston and rod with the 'puter just to make sure I don't have an
in the fit department.
Not a lot to report today. Spent most of my time turning that
cast iron into something square and clean.
And a fine hunk of iron it is!
Now that all the grunge, scale, etc.
is flycut off of the piece, I know what I have to work with.
Milled the keyway in the crankshaft and did a little CAD. I think
about done for now with CAD and can do some more whittling. I've
to try a PTFE (Teflon) "O" ring for a piston ring. Since it's
pretty stiff and a little bigger than my bore, I'll split it and gap it
metal ring. Here's
............ so far.
Some cast iron sawing got done today.
While running Engine Number Four to
test the Piezosparker or "Piezomag", I laid out and machined the
bore. Then, I laid-out the cut lines for the block and rough
Cast iron's messy.
I got the majority of the whittling done on the block.
It's beginning to look like an engine.
The next thing to get done is to make
the main bearing caps, bore for the bearings and hang the
think I'll make a 1/4" base plate for it so mounting will be
I'll also make a plate that covers the hopper and has a smaller opening
it. Since I'll probably be painting this engine, I may fill the
where the base plate and hopper cover go on and finish it off so, once
is on, the joints are invisible.
So far, I think I'd
flywheel to be on the usual side. That will put the sideshaft on
of the engine. This may change as this detail can be modified
mounting the sideshaft.
Doing the main bearings is taking a little time.
Cutting the main bearing caps from some of the sawn-off cast.
main bearing caps are made from a piece of the removed
cast when the block was roughed-out.
After milling the caps to size, the bolt holes were drilled and tapped.
My method of fitting bearings consists of first accurately measuring
the O.D. of
Halving the main bearing bushings.
the O.D. of the bushings is noted, they are accurately
marked at the halfway points in the circumference. In this case,
of the un-split bushings was 1.128".
I use a Dremel cut-off wheel with the Dremel handpiece mounted in the
chuck. I've clamped a drill press vise on the carriage and, with
Dremel going fast, I slowly feed the bushings into the cutter along the
After deburring the shells, they are held together and the diameter is
perpendicular to the cut lines. The measurement is 1.086" and
subtracted from the original O.D. of the bushings and a shim pack is
this thickness. In this case, the shim pack is 0.042".
Boring the main bearings in the block.
The caps are bolted to the block with
the shims in place and the block is mounted in the mill and the main
are bored to 1.125", giving 0.003" of crush on the shells.
After the boring is
I will put the bearings in place and check the I.D. against the O.D of
crankshaft. If I'm lucky, all I'll have to do is to hone the
little then lap them to the crankshaft.
made a big engineering decision yesterday. I've decided to go
different sized bushings for the mains. When I'd gotten the other
ready, I came to the conclusion that the thrust face of the bushings
narrow at 1/8". Ordered some bushings that will give a thrust
1/4". I'll turn down the O.D. to fit the bores in the block.
Today, I made shims, drilled some holes and made the base plate and the
unfinished hopper top.
Waiting for the epoxy to harden.
Tomorrow, I'll clamp the block in the
mill and match the surfaces of the hopper top and the hopper.
(says here in the fine print) I'll belt sand the top and fillet the
after painting, you'd never know that the hopper was pieced
Maybe I can get some "experts" to wonder how I machined out the inside
of the hopper. There
may be an "Aw Shoot!" brewing. The piston won't go in from the
back and the big end of the rod is too big to fit into the bore.
to go blythely along 'til I've finished the rod and see if the little
clear the top of the bore enough to put-in the wrist pin. If not,
have to think on it some.
It's slicked-up some and I have the mains made and lapped-in.
The top of the hopper gets levelled.
the epoxy hardened very nicely despite it being over
fifteen years old.
The sides of
lid are matched to the hopper
Chamfer applied to top of hopper.
you look at the photo above, you will see that I subscribe to
the axiom, "If you ain't with the tool you need, you need the tool you
got" (or words to that effect). I needed to chamfer the top of
hopper and all I had was a really old valve seat refacer. it's 60
and made a nice looking chamfer, although I had to feed it really
slowly to keep
from damaging or dulling it.
Main bearings being lapped.
won't be showing the steps to get the mains done. Most of
them were the same as I did with the previous bearings. The
turned to fit the block and the thrusts were adjusted to fit.
buttering some Timesaver lapping compound on the main journals, the
was assembled loosely with the shim packs. The crankshaft was
in the lathe and run at the lowest speed while the main bolts were
tightened. It is easy to tell how it's going by simply holding up
end of the engine and noting the torque required to turn the
The bolts were tightened until an increase in torque was felt then it
allowed to run for a while, adding thinly mixed lapping compound as the
worked-in. When the main bearing bolts were tight, I substituted
the lapping compound and let it run for a while to flush out the
Total time was about a half hour.
The works was disassembled and everything was washed in solvent.
bearings showed 100% contact and the crank looked good. The
process maybe took off one ten thousandth of an inch from the
reassembling, it was again put on the lathe and run for about another
minutes. The fit, when checked-out is excellent.
Here we are so far. Holding sideshaft gear up for ideas.
I'll take a day or two off the
project then will start on the rod.
right along, today the rod was partially completed.
Getting ready to lay the rod out.
lucky and found a chunk of 1/2" HRS that a portion of
which was exactly wide enough for the rod.
Laid out and the radiuses drilled.
sawing the blank, the major points were laid out. The
radiuses between the big end, little end and the rod are simply 1/2"
holes. After sawing out the bulk of the steel between the
rod was put into the mill and the rest of the steel was removed.
Then the rod was clamped in the vise at 45 degrees and the big end
Cap separated from rod.
will notice that the little end of the rod isn't per the
drawing. It is squared off and I've drilled a center in the
There's another center in the cap where the grease cup will be.
so, if there are clearance issues as the rod oscillates around the
it can be put into the lathe and the corners turned off. I'll
the rod's finished and the piston's done so I can assemble it and see
is any interference between the bottom of the bore and the rod.
well, I'll then finish-off the little end and drill and tap the big end
At this point, I inserted the rod into the bore from the back and
of room to assemble the wrist pin from the top.
Ready for shims and boring big end.
The rod bushing was cut in half then
measured to determine the shim pack to bring it into roundness.
pack ended-up being 0.040". The O.D. of the uncut bushing was
1.001" and I want about 0.002" of crush so I'm making up a shim pack
of 0.038". The thick shim is 0.036" so I've got to cut two
0.001" shims to bolt-up. The bore of the rod will be 0.999" to
make sure the bearing is held tightly. If it's too tight in the
rod, I can
always dress off a thousandth or two from the halves.
After the shims are
in and the
rod cap is tightly bolted-up, I will carefully lay out the big end
the little end.
The rod and the piston are done.
Here's what I got done today.
work today wasn't technically challenging, just time
consuming. The piston is made of 6061-T1 bar stock. I've
0.003" clearance in the cylinder. The bore is 1.125", so it's a
little close but should wear-in fine.
You can see the Teflon piston ring. It's fitted with the ends
together because I figure the "0" ring will quickly wear a flat where
it rubs on the cylinder and this will quickly open up the gap.
The grease cup is an extra I had from The Homebrew Engine project so
to be used on the rod. I will make some grease cups for the mains
Running-in the rod bearing.
I just got started lapping the rod
bearing. I'm using the finest TimeSaver compound so it will take
while. The way I do it is to set the shim pack just a hair on the
side, about 0.0005" or so. Then when I first assemble it for
I only tighten the rod bolts until there is substantial drag.
while, I can tighten the bolts a little then run it some more.
bolts are fully tight, the bearing is broken-in.
After it's run for a
I'll take it apart and see what the pattern looks like.
17 July 2013:
ran the engine for a while with
Here's what the rod bearing halves and the rod journal looked like this
Rod journal and shells after lapping.
I took it apart, I could see that the wear pattern was
100%. No more lapping was required. Since the bolts weren's
tight and the bearing was still binding slightly, I made one 0.001"
shim. Back together, it was still just a little tight so I
applied more of
the finest TimeSaver lapping compound (diluted in oil) and ran it until
free, about another 15 minutes. My guess is that the fit on both
and the mains leaves only a couple of tenths of clearance. I'll
be using a
light Teflon filled grease so it should work out fine. I guess
several hours of running, the fit will be between 0.0005" and 0.001",
good clearance for light grease.
Getting ready for paint.
After all that, it got taken apart
again and is being prepped for painting. It won't be super
the paint I selected is an old can of RustOleum Hunter Green that I'll
with a brush. In case you ask, if you click on the photo and look
carefully, the bearing bores and mating surfaces are masked as well as
think the sideshaft bosses will go. On the head end, I've masked
think the head will be. To the right of the engine, you can see
of cast iron I may be using for the head. It came off of the
block and is
the same width as the hopper end. All that is in question is if
enough room for the valves and combustion chamber.
The paint is applied, the sideshaft and mounts are mostly done and I've
couple of grease cups for the mains.
Sideshaft and grease cups.
waiting for the primer and paint to dry, I made the
supports and bearings for the sideshaft. Since I haven't figured
what the valve arrangement is going to look like, I masked-off a
mounting pad on
the block for the cam end of the sideshaft. The other mounting
pad is on
the back of the nearest main bearing boss.
The grease cups were sketched out and the tops and base are threaded
while the bottom where they screw into the block are 10-32. The
tapped in the mains with a plug tap and the cups thread in like a pipe
thread. I like my new knurling tool although I haven't quite
hang of doing matching knurls.
I just had to take a pitcher of it with it's paint and grease
Just before I quit for the day, I
made the oiler pipe and drove it into the bore in the cylinder block
LokTite. I don't think it's gonna leak or go anywhere.
While waiting for the paint to dry, I got some more parts made.
did some assembling.
beginning to go together
Do 'ya think I'll have wear problems on the sideshaft gears?
After getting the sideshaft mounts
done and having a look, I think the gears are just a little teensy bit
scale. I went with what I had! I don't think I'll have an
overloading problem. I
greased it up and ran it some more on the lathe. It now turns
smooth. Also, parts of the oiler (I'm making two - one goes in
drawer). I'm now waiting for the polycarbonate tube and some
to come in. The shipment should be here late Monday.
I was going to use
the sight glasses but, since I was ordering from McMaster-Carr anyway,
I got the
polycarbonate. I can cut it myself to any length I need.
The flywheel is going
about 8" in diameter and 1-1/2" thick. I ordered the ductile
iron for it along with the other stuff.
I think I can make
and valve cages out of cast scraps from other engines but haven't
The last couple of days were devoted to making the oilers and the wood
The oilers are a study in "Once you figure out what you're doing,
done". The polycarbonate tube is easy to cut and work on the
lathe. Making the small brass parts was more of a challenge and
Engine with oiler.
I still haven't totally figured out
the head and have several ideas for a cam-stopper but all of them are
complicated. I may just not do that. While waiting for my
grind out a bit more detail, I think I'll start on the flywheel.
fit in the lathe. If so, it will be easier to make than the
that have to be jury-rigged in the mill.
May 2013: Working
on the flywheel, it took most of the day to lay it out, bore the hub,
the O.D. and face it.
Really more than my l'il lathe is designed to do.
I probably shouldn't try something this big in my little
lathe. It was working really hard, tripping the mechanical
if I fed it just slightly more than really slow on the larger diameters.
Yesterday and today was spent finishing the flywheel and getting the
mounted on it's wood base.
I like big flywheels!
The hunk of cast iron I got could be
ordered either 1" long or 2" long. Since I wanted a 1-1/2"
thick flywheel, I ordered 2". When I got to machining it and
how long it was going to take, I decided to just clean it up and use it
little under 2". Also, I wasn't planning on the web between the
and the rim being over about 1". Again, it was taking altogether
long to o so it ended up being more like 1-1/2". It could be
considered to be an "electric" flywheel. As you can see, the
engine should run real smooth. If
it ends-up being too heavy, I can put it back into the lathe and face
1-1/2". Doing this would take more than a day to do.
last couple of days have been partly spent at the CAD
tried to lay out the head arrangement using simple notes and sketches
decided that there were just too many places to go wrong. Here's
view of what I've come up with.
An idea of what the head and valve actuation will look like.
The view above is facing the head end
of the engine. Of
course, the drawing doesn't show bolts or the valve details. The
springs and keepers are some I rescued from a dead 4-cycle weed
you can see, there's only one cam lobe driving both valves. It is
the "overlap" position just as the exhaust valve closes and the intake
opens. The duration is necessarily the same for both intake and
about 200 degrees. I can change duration by increasing or
lash. The rocker arms are 1:1 and the cam lift is 0.200,
enough for the engine to run. The
lash adjustment is pretty Mickey Mouse. Right now, the pivot
point for the
rockers can be moved around to change lash. I may change to
bolts if that doesn't work out.
In thinking about it last night, I figured I might as well put the
where they are supposed to be. Here's the new drawing.
The head is finished.
Cylinder head in place.
This was one of those days when
everything seemed to go fine 'til the last step. The problem
that two of the head bolt holes in the block somehow got drilled about
0.030" out of position. There are a couple of ways to fix
like that. One would be to plug the holes then re-drill the holes
right position. I couldn't do that because the block is cast iron
screws or plugs I would have would be steel. I was afraid that,
the holes were plugged and the new holes started in the correct
difference between the cast iron in one part of the hole and the steel
other part would make the drill drift.
My solution was
solution. That was to drill the two bolt holes in the head
oversize so it
could be shifted to the correct position.
I'm sure you'll never
soul what lies hidden behind the top two head bolt washers.
After a day or two
be tackling the valve cages.
Today I got the valve cages almost done.
Starting with a scrap from the 30-60 flywheel.
good I collected the left-overs from the 30-60
flywheel. One of the pieces from between the spokes was big
enough to make
both cages. Cast iron, even!
Cut into manageable pieces.
I cut the piece down the middle and trimmed off what I
didn't need. An end milling operation got them square then, using
4-jaw chuck, I drilled the valve guide hole, drilled the port and
turned the two
outside diameters. Since I turned the valve seats while the cages
still in the chuck, I shouldn't have much trouble getting the valves
The nearly finished cages.
When I drew the cages, I didn't get
the spring height right so I will have to make a spacer for the exhaust
increase the tension on it. The intake, done later, is all right
allowed another 0.031" for spring tension. I think that by
I should have the valves lapped-in, the gaskets made and the head on to
The valve cages are done and I got the valves lapped.
It's now got valves.
The only problem is that they show
good seats after the lapping but they leak when the cages are
At first, I thought the copper sealing rings were the culprit so I made
out of 0.031" high temperature gasket material. Same
After spending about four hours fiddling with it, it was quittin' time
Hoyt-Clagwell & Company. Tomorrow,
I'm going to do some tests to see if the problem is that the valve
distorting slightly when tightened down. If I loosen the cage
stand the chance of blowing the gaskets but I can see if the seal is
less compression on the cage. If
distortion is, indeed, the case, I will have to come up with a way to
do a final
lap with the cages in place. That will require removing the head
only four bolts, that's easy. In any case, today proved that the
piston ring will seal. With fingers on both ports, it will
develop a fair
amount of pressure. Now, how long it will last when the engine is
is another question.
Things moved along smoothly today. The valve seating problem was,
due to distortion in the valve cages when they were bolted to the
The solution was to remove the head and, with the valve cages in place,
the valves. They seem to seal well now.
Next up was to make
arm stand and rocker arms. These parts were plotted to exact size
plots were cut out and glued to the steel for the parts. After
was a simple job of following the lines with the bandsaw, belt sander
"O" ring seal on cage.
I was worried about leakage around the cage, I cut
grooves in the cages and made a chamfer and counterbore in the head as
above. This should make a really good seal. Now, whether
"O" rings can stand the heat is another story.
arms in place.
End view of rocker arms.
The only thing left to do with the
rocker arms is to drill and tap for the 6-32 adjustment bolts.
Now, it's time to
camstopper and cam. I've got to sort through the ideas in my head
up with a reasonably elegant design. Since I've never seen the
guts of a
camstopper, I'll have to re-invent that particular wheel.
June 2013: I'd like to thank the guys at Harry
SMOKSTAK for their input into the design of the camstopper I'm going to
for this engine. It took four design tries in CAD before I yelled
"Uncle!" and got help. What we now have is a sort of modified
Callahan mechanism. One
of the major things I had to work out was how to make the latch go
sideshaft. On the Callahan, the camstopper is located at the end
sideshaft and the shaft ends before the latch crosses it's path.
engine, the camstopper is before the end of the sideshaft so
ensued. What I've got should work.
I'm going to post the
drawings (in JPEG form) in case you want to get a headache figuring out
Thiis view shows the parts in the unlatched position (sideshaft driving
This view shows the parts in the latched position (Cam idling - miss
You should be able to click on the above images to get a
resolution view that you should also should be able to copy to your
printer. That may make them a little easier to read.
This is going to be
maybe I shouldn't even post the drawings. To give you a little
of the colors are: Magenta
Green - Cam and governor carrier.
Blue - Latch, latch arm, screws,
Yellow - Springs, sideshaft bearing mount.
Cyan - Driven part of the camstopper
Red - Shaft collar for
Black - Various pins, washer and short shafts.
I haven't gone to the
of hiding any lines. The hiding would make the drawings easier to
understand but is time consuming.
I'll probably get the
materials ordered and start making swarf tomorrow.
June 2013: Well,
yesterday I found out that I'd gotten some of the drawings reversed and
spend the day re-dimensioning all of the camstopper and governor
Today, I did get three parts made.
Slowly making progress.
The part that is partially done
(awaiting a ball bearing so I can drill and bore the mount) is the
bearing mount (yellow in the drawings). The other two parts
disc the weight arms ride on and the thrust bearing link to the latch
couple of the green parts). I've scrapped the previous head-end
I'm hoping to get some more parts made before I run out of stock.
A little more is done.
Making some progress on small camstopper and governor parts.
There are a number of small parts to
make for this engine, especially in the camstopper and governor.
almost at a standstill until I get some more metals and, in any case,
some other things to do so I'll probably take a couple or three days
More progress today. The governor parts are made and assembled to
The governor is about done.
As you can see, I've got it belted-up
to a variable speed motor to test the governor and break-in the
bearing. After the camstopper is built, I'll use the motor to
tweak the governor speed adjustment.
It looks like the
ignition and the mixer are going to be about the last thing I'll do
seeing if it will run. That will be a while yet because the
parts are pretty complex and will take some time.
I've finished what I call the camstop. That's not actually what
does. It's really the driving member of the stop assembly.
Here's the driving part of the camstopper mechanism.
part is what is solidly connected to the sideshaft via the
setscrew. When the governor allows the engine to run, the latch
the slot and, since it's connected to the cam, the cam turns. At
that's the way it's -supposed- to work!
This is what I call the latch.
was kind of tricky to build. I started out with a
piece of flat 1/4" thick steel and used the mill to make part of it
1/8" thick then used another milling cutter to hog-out the inside
curve. The outside curve was rough sawed then filed to the
contour. I left a little extra "meat" on it so it can be
whittled on to make it work in the assembly.
The Driving member with the latch engaged.
The latch is shown in the engaged
position. When in this position, it rotates with the driving
the cam, flipping the bar (in the background) out of the way of the end
latch. When the governor shoves the pin into the path of the bar,
forces the latch (against an internal spring)| toward the camera which
disengages it from the driving member.
Now that I'm done
governor, I may need to revisit the weights. It may not have
to effectively drive the rod into and out of engagement with the
After a few "aw-shoots", I now have all the major camstopper parts
After getting the cam made, I
assembled it and found the first Aw-shoot! The part I call the
(the friving member) has a ramp to make it easier for the latch to
the slot it. When I milled the ramp, I put it on the wrong side
slot so I had to make another.
Then, after all was
together, I found that, for some reason, the intake (lower) rocker arm
follower doesn't have the right relationship to the cam. As of
don't know what the problem is. So far, I found that the rocker
identical and the rocker arm stand is symmetrical. Tomorrow, I'll
it and find out just what's the matter.
Things are looking up!
I got the rest of the parts made and
assembled. The short answer is that, after a little fiddling, the
camstopper works. There are still some issues to address, the
them is that sometimes when the cam is operating, it declutches itself
intake valve is ramping closed. This causes the intake valve to
prematurely. I believe that by doing some filing on the latch, I
alleviate the problem.
although the governor does work, it doesn't have enough power to
the latch bar. I'll probably be making some heavier weights and a
spring to help the situation. The
rocker arm problem was fixed by making another intake rocker that has a
arm from the pivot to the cam follower. The problem is caused by
mis-alignment in the sideshaft. It was much easier to just make
correction with a new rocker arm than to re-do the entire governor and
mount. The valves operate correctly and there is plenty of lift
so I can
adjust the overlap (now about five degrees) by changing the valve
haven't checked the actual cam timing but, by looking at the crankshaft
as the valves operate, it appears to be pretty close to what I planned.
Today, I found out what was causing the jumping of the
wasn't enough engagement of the latch and that made it cam out of
when negative torque was applied. The fix was to machine a groove
inside of the cam portion of the camstopper that gave the latch another
0.050" to move into engagement. I think that problem is solved.
Next, since the
really didn't have enough oomph to positively drive the pin that
latch arm (the part on the outside of the camstopper), I made new
are quite a bit heavier. At "quittin' time", another problem
surfaced in the form of the thrust plate for the weight arms binding on
sideshaft. If I can't fix it the easy way, I'll have to make
plate, this one having a longer bearing area on the sideshaft to
New, heavier governor weights.
I think that, once this is worked out
and the rest of the bugs are fixed in the governor/camstopper, I can
get on with
a mixer and ignition and see if the danged thing will run.
Today I made a new thrust collar for the governor weight arms.
previous one only had a bearing length on the shaft of about
Since it is supposed to float on the 3/8" sideshaft, it would bind when
moving. I turned off the old collar in order to avoid damaging
thrust bearing and made a new collar with about a one inch bearing
It slides a lot easier with no binding. After a few tweaks
the governor and camstopper work well enough on the belt to rate a
It is below.
As you might note, there is
crankpin on the cover at the end of the cam. This will be used to
the piezoelectric ignition. No drawings have been made of this
but it will be different from the previous Piezomag. I'm trying
and easy to build. We'll see.
First, probably will
exhaust manifold and pipe and the mixer which I'll start on directly.
By the way, when the
motoring on the belt, it has intake suction and some exhaust flow so
it will run when it gets a proper fuel/air mix and something to light
The mixer and exhaust went quicker than expected and are done.
Head end of mixer (left) and air intake end of mixer (right).
exhaust and mixer bodies are made from some 5/8" thick
cast aluminum. The exhaust is simply a chunk of the aluminum
match the port then drilled for a tight fit of the tubing as shown in
The mixer is milled to match the port then drilled through with a 1/4"
bit. From the air intake side, I ran a taper reamer through to
the milled area at the port. The reamer small end is 1/4".
the air end, the hole is about 0.312" tapering to the jet.
The bottom (fuel end) of the jet is made of 1/4" hex brass stock.
stock is turned and a 10-32 die is run over it to screw into the mixer
body. A #60 hole is drilled from the jet end
to meet another hole from the fuel end and a length of 1/8" copper line
stuffed into larger hole and soft soldered into place.
The top end (needle valve end) body is prepared like the fuel end and
into the top of the mixer body. A hole is drilled and tapped 4-40
the jet for the needle valve. The needle valve is made by turning
tapered point on the end of a 4-40 machine screw. The head is cut
a brass knob is screwed onto the end of the needle and soldered into
Choke closed (left) and choke open (right).
the lack of a better idea, the choke is made of a piece of
0.030" thick aluminum that is bent to fit over the mixer body and
stay in place. A slot is cut so it can avoid the mounting
Slide the choke one way and it covers the air intake. Slide it
way and it allows the air intake to be almost fully open. After I
engine running and tweaked (whichmight necessitate somje changes to the
I may re-visit the choke for something a bit more substantial.
And here it is, almost ready to start on ignition.
I'll make a couple of mounting
saddles for the fuel tank and run the pickup tube (with check valve at
bottom) through where the 1/8" NPT plug is now located. At that
point, the ignition will be on the schedule.
The next couple of
be a break so I can do other things and marshal my thoughts on the
Not a lot has gotten done in the last couple of days. The fuel
mounted, the check valve is made and it's plumbed-up. I spent
some time in
CAD working out the piezoelectric ignition and have started making the
As of 18 June 2013.
The "dangly bit" hanging
from the end of the cam is
what I've so far gotten made for the ignition. The top end has a
female thread in it into which screws a rod (with locknut). This
the point at which the black cam trips the hammer of the piezoelectric
unit. The longer the rod is, the more advanced the timing
reason the trip cam is black is that I tried to oil harden it. I
think it hardened much if at all. The steel is some that I got
scrap yard and I have no idea what the alloy is. If this idea
the trip cam wears quickly, I suppose I can either armor the wear point
piece of hacksaw blade or buy some hardenable steel and remake the
Right now, since the ignition mechanism is experimental, there's no
to go to the extra effort and expense.
There are a few more parts to be made for the ignition but I'm guessing
all goes well, my first try at running it maybe in the next session. My
session may not be for a couple of days, though.
Back at it today. I thought I'd be able to see if it would run
because I screwed-up one of the ignition parts and had to do it over, I
got the ignition assembled before "quittin' time".
Partially assembled ignition.
don't know exactly why the trip pin was located wrong
but, because of that, I discovered that if you whack the piezo element
enough, it will make an almost 1/2" spark! How many sparks it
make before the element shatters when hit that hard is a good question.
After relocating the trip pin by eyeball, it now seems to trip at the
Ignition installed on engine.
Tomorrow, I'll finish
mounting the ignition and maybe I'll try to
start it. Whether it runs or not, I'll makie a video of the
As promised, below is
the video of today's first
attempt of The Mystery Engine. Although I did get it to fire
heat up, it never did make enough power to get off of the belt.
thinking that the problem is due to low compression. I don't see
evidence of excessive blowby and the valves seem to be seating so the
might be low compression ratio.Something I noticed was that ignition
didn't seem to make a lot of difference in the firing. I adjusted
between a little after TDC to quite a bit BTDC, ending-up with the
occuring just before TDC. Another thing is that, although the
piezoelectric ignition works well, it makies an irritatingly loud
Anyway, when the engine is
motored at just below
it can make enough power to boost its speed just enough for the
Better'n nuthin', I guess.
Over the next days, I'll work to get it to run right. It's only a
of fiddling with it 'til it cooperates. Stay tuned.
I had an idea last
night and, today, made an
adapter from a
quick connect air hose fitting to a 10mm spark plug. I used this
to do a
leak down test and found that the low compression problem was a very
sealing (non sealing?) piston rinhg. As you recall, I tried using
cut-down Teflon "O" ring for the piston ring. Here's what I
found upon teardown.
piston ring removed from engine.
As you can
ring was leaking badly. Since I had no other ring handy, I made
Teflon ring from another "O" ring. This time, I turned the O.D.
flat then added a spacer to the ring groove to make the edges
putting it back together, it really tried to run and, a couple of
times, when it
was running on the belt, I slipped off the belt and it continued to
on and off the governor a few times before pooping out. It didn't
enough to get a video. A little improvement may encourage me to
It could be
ring will need to seat to seal really well but, as of now, it will
bounce off of
compression although weakly. Tomorrow, I'll run it some more and
see if it
improves. If not, I may try my hand at making a cast iron ring to
oddball size ring groove. That should be easier than making a new
for a "store bought" ring.
The Mystery Engine ran on its own for the first time.
a smaller (0.150" diameter)
venturi and opening the valve lash a lot to reduce some of the
(about 15 degrees), the engine was started on the belt and tweaked
until it was
helping the motor. Then the belt was flipped off and the engine
to run on its own. It's still not making the power it should and,
get the overlap sorted out and the cam re-timed, it should do better.
yesterday's 30 minute
the modified piston ring, I did another leak-down test and there was no
detectable blowby. I checked the compression when motoring just
latch-out speed (cold) and got 55 PSI, which isn't bad.
the last couple of days, I've been sorting out various issues.
the valve overlap down to about 5 degrees while keeping the exhaust
about 190 degrees and the intake about 180.
governor has been adjusted to as slow as it will go and still
haven't measured the RPM but it is probably around 500 now. After
optomizing the rest of it, I'll try to work on the governor to make the
latch/unlatch speeds more predictable. Right now, sometimes, it
unlatched longer, allowing the engine to speed up more. Then it
a longer period.
I've reworked the mixer a bit with the mixture needle integral with the
jet. Before, the needle approached the jet from the opposite side
throat. This, I think, caused the jet to behave erratically due
needle being in the air flow.
the venturi was way too big at 0.200" diameter. I made an insert
guessed the venturi needed to be around 0.180" in diameter. After
lot of fiddling around, I found that there was no way the engine would
the choke fully open, letting me know that the venturi was too big and
velocity across the jet was to slow.
then bushed the venturi insert and drilled it 0.100". The fuel
mixture needle can now have an adjustment range with the choke fully
the engine has warmed-up a bit. Throughout, I've been tweaking
ignition timing and am now at about 15 degrees BTDC.
it is at a point that it can -almost- be hand cranked to start, I think
take a day off to cogitate my next moves.
now, I think I can safely increase the venturi diameter to around
0.120". This will allow a larger charge and, possibly, more
power. The engine still has to fire several times before the
latches so there is a bit of improvement to be made. The mass of
flywheel will probably keep it from single hitting to get up on the
latch due to
the power input required to raise the speed.
piezoelectric ignition is operating fine. Spark plug gap is
and I can detect no problems with spark.
this morning, with a cold engine and after about an hour of off and on
was still about 55PSI. I checked the leakdown and found that
there is no
detectable leakage past the valves or piston. The Teflon ring is
holding-up so far.
slogging away. Over the last couple of days, I've been tweaking
venturi size and think, after wandering around between 0.100" and
0.150" in diameter, I think I've settled (at least for the time being)
0.110". With this venturi size, I can run the engine without any
choke and still have needle valve adjustment range.
I reduced the cam duration which reduced the overlap.
checking found that the duration was about 200 degrees. Since
use the same lobe, it was fine for the exhaust but a bit on the long
the intake. You can see how much I took off of the lobe in the
above. I did it in two steps and now have about 180+ degrees of
for both valves. For an engine that's not going to work for a
fiddling got me to an ignition advance of about 20 degrees.
engine still doesn't just jump up onto the governor but it will take
where I think it's going to get the idea. It still has to be
checked the compression again this morning when it was cold. It
52PSI, a little lower than earlier but that could be due to the changes
intake, cam duration, overlap, etc. I'll check it again tomorrow
when it's cold.
30 June 2013:
I got a lot done with some small
improvement. First off, I pulled the head.
Head before milling.
Then, I decided to check the Teflon
piston ring. So far, it doesn't look as if it's allowing any
blowby. That's good.
Piston with Teflon ring.
If you look closely, you will see
the copper spacer ring above the Teflon ring. This is to force
the Teflon ring to fit snugly and slightly flatten the sides of the
ring where it contacts the lands. You can also see that I turned
the O.D. of the ring flat for a better seal against the cylinder wall.
Next, I stuck the head in the mill and took off 0.075" off
of the face to increase the
compression ratio. I connected an ammeter in series with the
motor and the controller in order to see if I could see the differences
in running when motoring.
The meter did, in fact, show a
slight rise in current as the piston came up on compression and a fall
when the cylinder fired. I could fiddle with the mixture and see
when I'd reached the sweet spot.
it ran a little better but was still puny. I found that the
running problem and funky fuel mixture adjustment range (a moving
target) was because the spark plug is a resistor type! I found
this out by measuring the resistance between the connector end and the
center electrode. It was about 7.5K Ohms, about enough to kill
the spark when the plug collected some carbon. The piezoelectric
ignition just doesn't have the muscle to fire the plug through the
resistor and the carbon.
The solution to this was to disable the piezo ignition and substitute a
solid-state module triggered by a microswitch.
New ignition setup.
The microswitch is actuated from
the crankpin that ran the piezoelectric setup. The switch is
mounted using only one screw so the switch can be moved to change the
timing while the engine is running. The dinner bell rang just as
I finished it. A very short test promises better performance of
the engine. We'll see.
1 July 2013:
It's running better than ever today. First, I re-timed the
valves so the middle of overlap is at TDC. Overlap is 20 degrees,
a bit much I think, for a flywheel engine but I'm planning on running
it that way some more while other tweaks occur to me.
I also adjusted the size of the venturi. Starting at 0.110", I
increased it to 0.125" with improvement. Then went to 0.136" with
another improvement. At 0.141" it was better. At 0.157", it
was hard to keep running without some choke and the mixture screwed way
out. The venturi was reduced to 0.147" and it seems to run fine
at this setting. The way the venturi is changed is by filling the
venturi part (the jet end) of the brass part with solder, then drilling
the solder to the selected size. That's a LOT easier than making
a new venturi for every test that requires a smaller opening.
Starting is still problematical. Cranking slowly (about the speed
the wheel can be flipped) with the spark slightly retarded and the
perforated choke plate completely closed and momentarily putting a
finger over the air inlet, it will begin to fire. I can take it
off the belt and most times, by slowly opening the choke, it will pick
up speed. Advancing the spark will make it come up on the
The best it's run, at times it will actually fire once, latch and coast
several turns before unlatching and firing again. Most times, it
has to hit between two and five times to get latched-up again.
More tweaking may improve this.
My main goal now is to get it to hand start. After all of the
fiddling is done, I will revamp the ignition to some kind of permanent
set-up using the electronic module and then it's ready for the last
video and showtime.
Here are some numbers after running the engine today:
- Venturi diameter 0.147" (#26 drill).
- Compression (cold) 65 PSI.
- RPM 475-500.
- After running for about 30 minutes, the following temperatures were
- Hopper water temperature 170F.
- At exhaust manifold junction with head 220F
- At mixer junction with head 190F
- Valve lash 0.010 both. (this gives the following valve timing):
- Exhaust opens approximately 170 degrees ATDC on the compression
- Exhaust closes approximately 370 degrees ATDC (compression).
- Intake opens at 350 degrees ATDC (compression).
- Intake closes at 550 degrees ATDC (compression).
3 July 2013:
Since the engine seems to be running about as well as it's going to
until I get some more ideas, I decided to go ahead and make-up a more
Showing timer and auxillary spark gap.
timer is simply a bronze spring that makes a ground contact with the
small crankpin on the end of the camshaft. The screw with the arm
on it is to adjust the timing. The cam turns clockwise and the
sooner the crankpin touches the spring, the more advanced the timing
is. The advance screw bears against the spring to change the
position of the contact so the
crankpin grounds it earlier or later. Turning the arm clockwise
retards the spark.
Those of you who look for the fine details will see a small
electrolytic capacitor (one microfarad) which is there to stop the
ignition from triggering due to contact bounce. It triggers on
the first grounding of the contact. Subsequent groundings during
that ignition period are ignored.
While testing the ignition, the engine began faltering, then would
quit. After motoring it for a few seconds, it would start and run
for a while before stopping again. Choking wouldn't revive it so
I knew fuel wasn't the problem. Eventually, when it started
faltering, I quickly pulled the high tension lead from the module and
made the spark jump a quarter inch or so. The engine immediately
picked-up again. The problem is in the crummy spark plug.
I'm getting to really hate those things.
As you can see, I've made a "Hot Spark Intensifier" (as they were
called years ago). All it is is a spark gap that allows the
voltage from the coil to rise to a higher value before jumping the
gap. Since the voltage is higher and, when the spark appears, the
space where the spark is more or less a dead short, the effect is
higher current going to the plug. In normal operation with a
non-garbage spark plug, the spark jumps both the intensifier gap and
the plug gap at the same time.
If the plug is slightly fouled, the initial path to ground is through
the carbon buildup. With the higher voltage, there is enough
current to overcome the shunting of the carbon and allow the plug to
fire normally. At least, that's the conventional
explanation. Makes sense to me.
Anyway, I didn't have enough time to test the "Hot Spark Intensifier"
this afternoon and this may have been a good thing. The clear
tube of the intensifier is made of plastic and it's probably not a good
idea to have it located at the spark plug where it could get hot enough
to melt. I'll modify it so it can be placed at the coil end of
the plug wire.
5 July 2013:
Spent part of yesterday and all
of today making piston rings. I have my doubts about the lifetime
of the Teflon ring so I decided to make a new one out of gray cast
iron. I had a hunk left over from making the piston for The
Hvid and used that. Here are the steps. The result is at
Bore the I.D.to the relaxed diameter of the finished ring.
Turn the O.D. to a few thoushadths over the relaxed diameter of the
Part-off the ring a little longer than needed to fit the groove in the
Here is the parted-off ring.
Using emery paper, lap the thickness of the ring to fit the piston.
Cut the gap in the ring so, when it is squeezed down, the ring will be
a little over the finished diameter of the finished ring.
Using wire, compress the ring using a mandrel to keep the ring
Here's the ring, ready for turning the finished O.D.
Turned to the finished O.D.
Here's the ring on the piston.
Here's the result of almost two days work.
I think the procedure is correct
but the execution leaves a lot to be desired. The ring on the
left is the first one I made. Unfortunately, it didn't have
enough pressure on the cylinder wall and wasn't thick enough to seal
well in the ring groove. Result: low compression and a lot of
I then made another blank using another set of dimensions. This
time, it was too thick and, when I tried to squeeze it down to the
finished I.D, it broke.
The third ring was dimensioned to be thinner than the first one and
thicker than the second one. The same thing happened to this
one. I'm sure if I tried again, I could get a decent piston
ring. As it was, I was disgusted with the process and put the
Teflon ring back in with a corrugated 0.005" brass shimstock
expander. So far, motoring hasn't gotten the compression back up
point that the engine will run.
Not so much fun today but tomorrow's another day!
15 July 2013:
It's been a while but I've been
piddling with piston ring ideas and having little luck. After
fooling with cast iron for the rings with no success, I tried making a
ring out of brass.
Brass - not so good.
As you can see in the above photo,
the brass distorted and shoved the piston hard against the bore,
causing galling. Scratch that idea!
Then, I tried another one of the Teflon "O" rings, this time with a
broader flat on the cylinder wall contact area.
The second try with a Teflon "O" ring.
This was also unsuccessful.
The engine couldn't develop any compression at all, I think, due to the
non-flat contact area on the groove wall.
Then, I ordered some square cross section Viton"O" ring stock.
Viton piston ring.
I should have known this would be
problematical. Although the Viton had the possibility of making a
good seal and had a 250F temperature rating, when the material was
formed around the groove in the piston, the width at the I.D. grew
enough that it bound in the groove at the bottom and was sloppy at the
outside. The engine did develop about 30PSI compression but after
motoring it for a couple of hours, it did not improve.
The next material tried was oil filled Nylon.
Oil filled Nylon piston ring.
The jury's still out on this
one. Since this material grows a lot with heat, I machined a
first ring with about 0.010" side clearance. This was not
successful, giving only about 35PSI compression.
I made another ring, this time with only about 0.001" side
clearance. This one gave about 40PSI compression and the engine
tried to run although, when it warmed-up, the ring was binding.
After a couple of warm-up and cool down cycles, it seems to be sealing
better and has a better fit although it still binds a little when
hot. Tomorrow, I'll cycle it a few more times to see if it
improves. If it improves substantially, I'll run the engine until
I can see that it is going to last a long time or will be yet another
Based on what I've experienced above, I ordered a piece of Teflon bar
stock to make a ring out of. The Teflon is good to over 500F, is
very slippery and doesn't grow in heat as much as Nylon. I'll
probably eventually go with the Teflon in any case, as it will make a
better material for long life (I think).
Of course, if all else fails, I can always just make another piston and
order a 1.125" X
0.09375 thick ring and be done with it.
I've been having some font issues with this page displaying on an
Nothing I do seems to fix it so, unless one of you knows a sure fix,
have to live with it. The problem doesn't show up on Windows
started this website
Kompozer. I'm now back to the old Microsoft Front Page using
one of the "legacy" fonts that's supposed to work for
everything. We'll see how it works.
17 July 2013:
ran the engine for a while with
the green (oil filled Nylon) ring and, althouh it sealed, when the
engine would warm-up, it would expand enough to bind in the
Since the Teflon
came in yesterday,
I made a ring out of that material that fits in the 0.195" wide groove
in the piston.
Teflon (PTFE) ring on piston.
I made it with a
snug 0.001" side
clearance and it has an 0.001" clearance in the diagonal-cut gap.
Compression before running the engine was an impressive 68PSI.
The piston now runs without binding when the engine is hot.
the engine, I think I
have another problem. Since the compression is good and the
leakdown test shows no leaks, the compression may now be too
high. When motoring the engine, as I advance the ignition timing
past about 10 degrees BTDC, i'm getting what sounds like detonation
knock. Since I'm running it on naphtha, which has a very low
octane rating, that might be the cause of the knocking. Just
about the time the timing is advanced to a point where the engine acts
like it will almost run on it's own, the knocks appear.
Next time I
fiddle with it, I'm
thinking of draining the naphtha and substituting non-ethanol pump
gas. If that fixes it or makes it better, I'll try a thicker head
19 July 2013:
Changed over to stinky
non-ethanol pump gas and ran the engine for a while. Although it
ran better and actually got off the motor, it still tended to knock
when approaching what seemed to be the sweet spot for ignition timing.
I lowered the compression ratio by replacing the 0.031" thick head
gasket with one twice as thick. There was little, if any,
improvement. Another thought occurred and that is that there was
a black soot spot on the piston head opposite the intake port.
Could there be a big problem with my oddball combustion chamber
idea? Here's a repeat photo of the combustion side of the head
(before milling to raise compression).
Cylinder head showing combustion chamber(s).
raise compression even more, I pressed inserts in each end of each slot
to take-up more space. The gas flow in the head (I think) causes
the mixture to be stratified with the non-purged exhaust gas.
This makes it fire the mixture only when it's correct when passing the
plug. Of course, the mixture is purer (richer) inside the intake
passage. Once the mixture fires, the flame front quickly moves
toward the intake chamber where it's richer. This rich mixture
causes the soot spot on the piston.
I tried shaping the intake passage where it enters the combustion
chamber proper. This is in order to get the fuel/air move
directly to the plug. This seems to make the engine run a little
better and have more response to the fuel mixture adjustment.
Since removing metal in the combustion area will lower the compression,
I may have to eventually go back to the thinner gasket. Some
thinking on it is in order before whittling any more but this might be
the right track.
This engine of the few I've made (with the exception of The McVickerish
Engine) has been the most reluctant to run well and may show the folly
of trying something new without properly designing it.
If I had thought it out more, I would have given the engine a longer
stroke (meaning that I would have had to buy a hunk of steel rather
than using a "scrap"). With a longer stroke, the combustion area
could have been bigger to give the same compression ratio. With a
bigger combustion area, I think the engine would have run well right
after I'd gotten the piston ring worked out.
20 July 2013:
There's a little improvement to report today. The frustrating
thing about this engine is that no one improvement has been really
significant. Just a lot of very small steps ahead, some
setbacks then more progress.
the previous image,
you can see the three "improvements" to the combustion area of the
head. First, to raise compression, I've milled the head so
there's just enough space left to give clearance between the spark plug
and the head of the piston at TDC when using an 0.031" head
gasket. The second (questionable) improvement is the insertion of
the four slugs into the port areas to remove some more volume from the
head, giving more compression. The latest improvement (which
seems to work) is to relieve the intake and exhaust port openings into
the combustion area of the head;
The theory behind this relief is to improve gas flow in the head.
I may do some more whittling on these areas of the head to get burnt
gases out better and fresh mixture in better.
It's been a hassle from the beginning of the testing phase of this
engine to regulate the choke. Today, I made a flutter choke.
Flutter choke on end of mixer.
flutter choke is nothing more
than an extension to the air inlet side of the mixer that has a disc
that is spring loaded. The disc blocks air into the
mixer. The spring allows the choke to open more fully as the
engine gains speed and the velocity of the air increases. I've
found that a flutter choke (as seen on a lot of the Fairbanks-Morse Z
series engines and others) allows the engine to run at varying speeds
and loads without having to adjust the mixture needle. Of course,
most of the engines that use this feature are throttle governed but
there's no reason it won't work on a hit and miss engine, too.
Before quitting for the day, I test ran the engine with today's
"improvements". It seems to get up on the governor a little
quicker and appears to hit a little less often when tweaked.
Since it was running low on gasoline, I refilled the tank with naphtha
and it ran just as well after a minor mixture adjustment. It's
still not nearly ready for "prime time" because I want it to be where
it hits once or twice then coasts for several revolutions. Not
nearly there yet.
Another thing I'm seeing is a "sorrying-out" condition when the engine
has run for several minutes and is close to a stable temperature.
It begins taking longer and longer to get up on the governor until it
finally doesn't latch out at all and slowly loses RPM until it finally
quits. I don't think it's a drag issue (something binding with
heat) because the engine spins freely right after it stops. It
could be that the mixer is getting hot enough to boil the fuel but
I'm not sure yet.
21 July 2013:
Today there was a little more progress. First, since the engine
ran for a total of about an hour yesterday and sorried-out about
quittin' time, this morning I
pulled the head and took a look.
Piston and head after teardown.
As you can see
in the left photo
above, there is a carbon spot opposite the intake port. I think
this is caused by the rich mixture trapped in the port area blowing
into the piston. On the right is the head, showing the soot
pattern around the plug.
Head, after further removal of metal
around intake port.
I removed more
metal in the port
area and reassembled the engine with the original thinner 0.031" gasket
to raise the compression to compensate for the increased volume in the
head due to metal removal.
The engine ran marginally better and I think it was hitting fewer times
before latching. Since it ran a little better and didn't seem to
want to detonate as easily, I decided to remove the 0.031" head
gasket to raise the compression. Since the block and head mating
surfaces are really flat,
I just applied a very thin coat of high temperature silicone gasket
sealer and put it together. No leaks.
I knew that removing the head gasket would cause interference between
the spark plug and the piston. I could have just used a second
gasket under the plug but that would have decreased the compression a
Spark plug before and after relieving.
did was to modify a spark
plug by cutting off part of the side electrode then hammer it down and
file a gap. My figuring has the plug clearing the piston by a few
thousandths. A miss is as good as a mile!
After putting it all back together, it seemed to run better than ever
although I'm still not impressed. At one point, it was hitting
twice between latches but that didn't last long. After about 15
minutes, when it was completely warmed-up, it began running sorry
again. It didn't immediately quit - it just gradually slowed down
finally stopped. I believe the sorrying-out is caused by the fuel
overheating. Tomorrow, I may press a water dampened rag against
the mixer when it starts sorrying and see if it begins to run a little
better once the mixer cools some. If that works, it will prove
that the liquid fuel is boiling and I'll be tempted
to build and test a propane system on the engine. There's less
energy in the gaseous fuel but I don't think the heat will affect it as
I'm coming to believe that most of the wimpiness in the running of the
engine is due to a poor cylinder head design on my part. Because
of this and in spite of tweaks, I don't think this engine is ever going
to be a strong runner. I'll keep piddling with it to get it as
good as it will get.
At the end, I may also try converting the intake to atmospheric.
Doing that will eliminate any possible intake duration issues. It
would be a shame to abandon the powered intake valve but, if it makes a
great improvement in performance, I'll just have to live with it.
22 July 2013:
Well, dang! This morning, I messed with the mixer with no
improvement. Then, I noticed a little blowby so I pulled the head
piston ring after about two
hours of off and on running.
Teflon ring looked good, only
showing a little leakage around the gap. For the most part, the
surface finish was shiny and smooth. I believe that, if sized
correctly, Teflon should make good low performance piston rings.
Since I'm bored with doing rings, I just ordered a couple of 1.125" X
3/32" cast iron rings from Starbolt. I've got the new piston done
all except for the ring groove which I will do once the rings come in.
I did say ring(s). Knowing my luck, I'll probably break
one. If I don't break a ring, I think I know what the bore will
be of the next engine! :-)
We now pause for ring delivery.
28 July 2013:
Well, I've got the new piston made and the cast iron "store boughten"
ring in and, although I've motored it for an hour or more, it still
doesn't run worth a hoot. I'm going to motor it a couple of hours
more and; once the ring is seated and compression is up, it should run
Today, while motoring the engine, I changed intake and exhaust cam
timing (as much as you can on such cam and follower arrangement) and
saw very little change in the poor operation of the engine. With
the timing set so the exhaust opening is at about 40 degrees BBDC and
closing is at TDC and the intake opening about 5 degrees BTDC and
closing at about 20 degrees ABDC, I'd think the engine should run
robustly. Although the mixture and ignition timing can be set so
the engine fires regularly and the exhaust sounds normal, it just won't
"thrive". It has to be motored almost to governed speed to start
and will not continue to run for long after the belt is removed.
I even tried removing the intake rocker and making the intake valve
"automatic". The engine ran worse with this arrangement even
after tweaking the spring tension.
I'm beginning to think that the head/combustion chamber design is at
fault. With the present cam and valve arrangement, there's not
much that can be done to improve gas flow in the combustion chamber so,
if the engine doesn't decide to run well (which it should!), I may have
to re-think the head and valve arrangement.
I suppose I could convert it to have a face cam operating the rockers
and a conventional valve arrangement. This would give a
conventional combustion chamber. It would be a lot of work and
I'll consider it to be a last resort effort.
30 July 2013:
Today, I pulled the head and piston and cut a second ring groove and
installed the second ring I'd ordered. Originally, I ordered the
second ring so, if I klutzed the one, I'd have a spare.
The second ring is to eliminate any chance that there is no compression
loss past the rings. In setting up to cut the second ring groove,
I needed to freshen-up the center and, in so doing, drilled right
through the piston head.
piston with second ring.
wanting to make an entire new
piston for that small problem, I simply tapped the through hole 6-32
and inserted a screw with a locking nut on the underside. Works
for me! Also note the spark plug relief in the piston head.
This allows me to use a normal plug when no head gasket is used.
While it was apart, I whittled a little more on the combustion chamber,
trying to improve flow and also opened up the throat in the mixer,
thinking it needs to breathe better.
As is usual for this project, after I got it all back together and
motored it for a while, there was precious little improvement and it's
still not to the point where it will run on it's own. It sounds
like an engine but doesn't run like one.
31 July 2013:
This is getting to be riduculi (the plural of ridiculous).
Compression is apparently the problem so I pulled the head and
piston. To eliminate some unused space in the combustion area, I
bored the head as shown.
Modifications to head and piston.
The idea was to
take-up more volume
using a piston spacer than was added by boring the combustion area.of
the head. After relieving the piston spacer for the valves, I
don't think a lot of volume was lost. Motoring didn't show any
noticeable improvement. I think there is some intake valve
leakage which I will look into. This leakage could be due to a
slightly bent intake valve due to the piston spacer not being relieved
enough. We'll see.
2 August 2013:
I've now done everything and nothing works. I'm getting the
sneaking suspicion that because I didn't actually design the engine,
something is intrinsically wrong. Valves are seating fine and I
moved the cam and ignition timing all over the place with no noticeable
change in performance or the lack thereof.
3 August 2013: NOWI
know what the problem is!
Everything was measured. Way back, when I made the crankshaft, I
said the stroke was going to be 1.250". Today, when I measured
the stroke with the piston in the bore, I got 1.156". I have no
idea how that happened unless I made a command (non-documented) change
when I was making the crankshaft. The displacement is 1.149 cubic
Then, I measured the combustion space including the valve pockets minus
the volume of the piston extension and came out with a figure of an
ablolute maximum of 3.6:1, probably less. There is no way I would
be able to reduce the combustion volume so that is a maximum
compression ratio using this design. The only way the compression
ratio could be increased would be to increase the stroke by more than
space would allow.
There will be a donation to the scrap pile and a new head and valve
arrangement will be done. To keep the camstopper, I'll have to
work out a face cam and new rocker. To keep it relatively simple,
I'll probably just use an atmospheric intake valve. This time,
I'll actually design it so it will work.
Oh, well - back to the old drawing board.
4 August 2013:
Okay. I've redesigned the
head and valve arrangement.
Head end view of the new arrangement.Side view of
the new arrangement.
should work fine. I've
got it set-up for around 6.5:1 compression ratio with no head
gasket. If it doesn't seal, I'll make an 0.031" thick gasket.
As you can see, I've found that I can use the original cam by using a
bellcrank arrangement. The cam drives a follower that is guided
and contacts the adjustment screw. This rotates a horizontal
rocker arm. This rotation is transmitted through a shaft to a
vertical rocker arm that contacts the exhaust valve (the valve springs
are not shown). The intake valve will be atmospheric. The
exhaust port exits the top of the head and the intake is at the bottom.
The spark plug is threaded into the side of the head.
After dimensioning the part drawings, I can start whittling.
6 August 2013:
All that's left to do on the head is
to lap the valves.
The almost finished new head.
Next, I'll start on the rocker arms
6 August 2013:
The head is finished and on the engine.
head in place.
I'm making the parts for
the rocker shaft. It'll probably be a couple of days before I can
get those parts finished and on the engine.
9 August 2013:
The design I came up with for the
rocker arm/shaft assembly is
pretty labor intensive.
arm stand and in place.
Partially finished cam follower
guide shown on base board.
rocker arm stand was whittled
out of a hunk of 3/4" thick steel. If you look closely, you will
see that it took some extensive milling go get the necessary
shape. In the same photo, you can see the cam follower guide
which is also labor intensive. The design allows for a 0.150"
lift for the exhaust valve and a 1:1 ratio on the rockers which
necessitated removing some of the lift from the lobe.
The rocker arms will be made of 1/4" steel and I've found the last
piece in my pile which I hope is big enough. The design has two
rocker arms. One from the lifter to the rocker shaft and the
other from the rocker shaft to the valve. This was the only way I
could think of to get the cam motion to the valve in the new
head. I'd considered a face cam but am not sure I can actually
machine one that is accurate.
Tomorrow may have the valve train done then it's on to making the
camstopper work at the new cam angle. This will involve some
diddling with the latch arm shape.
I'm thinking of making the mixer out of some 1/8" NPT pipe using the
needle valve and jet assembly off of the mixer for the failed head
All I can say is that, after all this work, the little sucker had
10 August 2013:
The valve train is done.
Valve train finished and a look at
the re-timed camstopper.
a bit of fiddling but the cam follower and rockers are finally
finished. I had time to modify the canstopper trip.
In the photo above right, you can see the cam block I added to the
latch arm. This causes the camstopper "button" (seen at about the
bottom of rotation) to be pressed when the cam is straight up instead
of at tbout the 2 O'clock position as it was with the previous
After setting the cam timing and as the day ended, I couldn't resist
hooking-up the belt and motoring it a little. With only one valve
to operate, the camstopper is now surprisingly quiet and seems to
latch-up more smoothly now. It has very good vacuum and the
exhaust flow is much better. Now that the compression ratio is
up, I can hear blowby past the rings which should finish breaking in
once the engine is running.
I'll be taking a couple of days off from the project and when I return
to it, all I'll have to do is to rig-up a mixer and hook the ignition
14 August 2013:
Well, the mixer's done and everything is in place.
All dressed-up and no place to go.
The improvement - - - - NIL!
Leakdown shows that there are no compression leaks at valves, head
mating surface or rings.
It's got good compression - 85PSI.
it's drawing fuel nicely to the mixer.
The intaike valve flutters properly (tried several springs).
Cam timing (at "optimum" performance) is opening the exhaust at about
20 degrees BBDC and closing the valve at just a shade (5 degrees or so)
There is no binding of the bearings or piston.
Intake and exhaust are free of obstructions and are sized for good flow.
It sounds like an engine running (and it is, indeed, running!) and the
spark timing and mixture adjustments do what they're supposed to
do. The only problem is that it just doesn't want to be weaned
off of the motor and it doesn't seem that there is any certain speed
it's happier at.
At this point, I'm open to suggestions. Otherwise, I'm gonna
shelve it for the time being and work on getting the 30-60 engine to
15 August 2013:
Last night, I had the thought that the flywheel may be too heavy.
My theory is that the mass of theflywheel can't be accelerated faster
than the combustion gases cool. Although there is good combustion
and the heat generated causes the pressure to rise nicely, the piston
can't move down the cylinder (allowing expansion of the hot gases) fast
enough and the heat is lost to the cylinder wall.
This morning, I had two emails stating about the same thing.
David Jones thought the flywheel had too much mass and Denis Basson
offered some calculations showing that a flywheel weighing about 2 lbs
at the rim with a diameter of approximately 19 inches and about 5/8"
wide would work.
Barbell weight next to the original flywheel.
Not having that size of material and
not having the space between the crankshaft and the base plate of the
engine, Ihad a look at ye olde junkpile. I came up with a couple
of 3lb barbell weights, about 5-3/8" in diameter and 3/4" thick.
Although it wouldn't provide the ideal momentum, I figured that I could
at least prove the theory. I made a bushing twice the width of
one weight, broached for the gib key and bored one of the weights for a
press fit of the bushing.The original flywheel is about 8"
in diameter, 2" thick and weighs
21.2 lbs. After whittling, the barbell weight and hub weigh about
lbs. When I tried this on
the engine, it appeared to not have enough flywheel because it wouldn't
carry-over and as soon as the belt was removed, the engine would
quickly come to a stop.
Plan B was tried and the second barbell weight was bored and faced to
be pressed onto the hub. I got in a hurry and got the fit too
tight and here's what happened.
Now, I've got to go back and do it
the hard way, starting with a large hunk of 1/2" steel plate, cutting a
circle out of it and making a hub. I'll rely on Denis to
calculate if a diameter of about 8" will give enough momentum.
One thing I did do with the original flywheel back on the engine was to
try to test the theory by blocking out the governor and spinning the
engine really fast to see if it seemed to run better at higher
speed. This would test the heat absorption theory. When I
spun the engine as fast as the motor would go (about 1,200 RPM), the
engine seemed to run a little stronger and would almost hold it's own
off of the belt.
22 August 2013:
Nothing much is happening with the
engine. I've been trying to get a flywheel blank waterjet cut out
of 1" thick steel and, so far, the shop hasn't had time to do the
job. They're waiting until they have some other work for the
waterjet machine so, since I'm getting a rate based on slack time, I
will have to wait.
One thing I have done is to re-make the cam follower using a smaller
diameter ball bearing. This reduces the exhaust duration to about
around 200 degrees. It seems to try to run a bit better although
still not weaned from the motor.
29 August 2013:
The shop called yesterday and, today, I picked up the blank for
the new 1" thick flywheel.
I still have to hone the bore to
fit the crankshaft (it alllllllllmost fits) and broach the keyway then
the engine will be ready to start testing again.
In the meantime, I reworked part of the governor to try to make it a
little more responsive. Also, fiddling with the cam timing and
duration along with adding a flutter choke to the mixer seems to have
the engine running slightly better. I have my doubts that the
new, lighter flywheel will make the engine spring to life but I would
welcome a pleasant surprise. I should find out tomorrow.
30 August 2013:
The flywheel is on and I've test run the engine with it.
The new and lighter flywheel is mounted.
After warming up a bit to get it
into it's best running condition, the engine actually does run a little
better. Since all of the changes have been incremental, I have to
be happy with little bitty improvements. I think that, if I was
lucky, I could flip start the engine after it's warmed-up. Since
the motor's there, I just start it on the belt.
I think the improvements came from most of the changes made. The
new head allows a much higher compression ratio along with better gas
flow. Reducing the valve duration to about 220 degrees also
helped. Other changes include a better mixer with flutter choke,
refinements in the governor and, of course, more break-in time.
I've shot a last (for the time being) video before I put the engine on
the shelf. Developing this one to the point where it's almost
ready for prime time has been a trial. If, in the future, the
problem with it hits me in the face, I'll take it down and fiddle with
it some more.
29 August 2013:
I said that I had some "left-overs" or parts that didn't work
out. Yesterday, I collected them so I could box them up and put
them away with the engine.
Left over parts.
On the lower right of the photo is
the piezoelectric ignition which I think I'll box separately.
That part worked fine but, since I was having spark plug problems along
with everything else, I used a known hot ignition system. I may
use it on another engine in the future.
There's a lot of time and effort in all of those parts which goes to
show that starting off with a design is good.
I took the engine off the shelf after better than two years and decided
to try to make it run better. First off, I gave the flywheel some time
to make it look better. A day and a half and a waste basket full
of swarf and you can see the result in the last photo for today.
took the head off and re-calculated the compression ratio. By
dividing the stroke by the head-space (a short cylinder shape), I got
about 8:1 which seems on the high side. When taking the volume of
the spark plug and it's port into consideration, the ratio is nearer to
6:1. Thinking that a bit more compression couldn't hurt, I made
an 0.062" spacer to fit on the piston head.
at TDC as before.
Spacer ready to
with spacer installed.
Piston at TDC after spacer. Running today.
The rings and cylinder bore looked okay so I lightly honed the cylinder. After
putting it all back together, I tried to hand start it but ended-up
having to use the motor to get it tweaked until it wanted to run.
I think it runs better now but it still takes the motor to get
started and, once latched-out, it takes several hits to get back to
latch speed. There doesn't seem to be much blowby but I will run
it some more to see if it does any better with the rings re-seated.
It sure doesn't feel like it's got nearly 7:1 compression ratio.
More work is needed.
1 July 2016: It's been a while but my excuse is that I had to get my stub finger whittled on again and had to stay out of the shop.
the meanwhile, I've been fiddling with the engine. The piston
spacer worked - sort of - but caused the exhaust valve to interfere
with the spacer when the engine was latched-out.
To try to fix
that, I removed the spacer then milled 0.040" off of the head.
THAT sort-of worked but now, I had a lot of blowby.
the piston fit wasn't optimal, today, I made another piston. This
one is made of cast iron instead of the 6061-T1 aluminum.
the piston from a piece of scrap.
the bore several times, I came up with a dimension of 1.125"+.
The piston was turned to 1.126" then sandpapered down to where
the piston is a slip fit in the bore with slight tightness. I
plan to motor the engine with the head off for a while to let the new
piston get to know it's bore and make sure nothing binds up. The
piston clearance should remain the same regardless of temperature
because the block is also cast iron.
I'm using the old rings because now, I'm relying on the close fit of the piston to do most of the sealing.
Tomorrow, I will put it all back together and see if it wants to run any better.
2 July 2016: The short answer is no (it doesn't want to run better).
about an hour of motoring and fiddling, it was running but not on it's
own. In desperation, I decided to revamp the exhaust cam.
Because of valve/piston interference, I had to run enough
clearance that the duration was only about 120 degrees.
exhaust cam before modification.
I modified the
cam by turning down the lobe enough to have the valve just clear the
piston with zero lash. After turning the lobe, I put it in the
mill and milled a new detent dip so the cam would stop in the open
Did another test run. No joy! The engine still doesn't want to get off of the belt.
checked the compression and it was a little over 100psi which is good.
There is no valve leakage. There is very little blowby.
The engine turns smoothly with no binding.
I guess the
next thing is to hog out the mixer to see if I can get more mixture
into the engine, although it -looks- about the right size. I may
also fiddle with the flutter choke, maybe putting a fixed choke in it's
place. I need enough suction for the mixer to draw fuel but any
more than that and I'm just throttling the engine.