This is yet another in the series of misguided, confused and clumsy attempts to design and build an unusual engine from scratch.
engine is going to be unusual for me in that it will be inverted and
will have slide valves along with a throttle governing system I've
never seen before. It will throttle by changing the positioning
of the intake valve. In other words, I will attempt to use the
governor to control how far the intake valve slides. At full
throttle, the slide valve will move to fully uncover the intake port.
At cutoff, it won't be allowed to move far enough to open the
This might be problematic because at minimum throttle,
the intake port will only open a little at mid-intake stroke. I
think this will work but, at less than full throttle, the engine will
be sucking a vacuum before the valve opens, making the intake sound
bore of the engine is 1.544" and the stroke is 2.500", giving a
displacement of 4.681 cubic inches. The compression ratio as
designed is 6.2:1.
The reason the bore diameter is odd is that,
due to some machining errors, to clean the bore and make it straight,
it had to be enlarged from the original 1.500"
1 November 2013: The piston is turned, bored, etc.
the O.D. of the piston.
The finished piston and liner.
you can see, I'm trying the PRFE (high temperature Teflon) for the
rings. Since the piston ended-up about 0.020" undersized because
of the liner bore screw-up, I've sized the Trflon to take up the space.
I don't know how this will work. If it doesn't work, I'll
make another piston out of 6061T1 aluminum.
6 November 2013: Yesterday, I took a trip to the scrap yard and, after rooting around in the piles, I got the following steel for the project.
The steel for the project.
piece standing up is 1" thick and about 12" X 30", burned off of a
larger piece. I would have liked to get the whole piece but it
was too big to fit into my car and there's no way I could carry it.
Heavy! The 1" steel will be used for the engine base
(cylinder head), the valve clamping plate, the main bearings and
the crankshaft timing gear. I may have gone a bit on the heavy
side for the head and valve plate but I want these to be really stable.
triangular piece laying on the ground is 3/8" thick and may be needed
for the eccentrics that drive the valves. I'd really like to make
these parts out of bar stock but, if they're too expensive, I'll have
them cut out of the 3/8" stock.
rectangular plate laying on the concrete is 1/2" thick and about 12" X
36". It will be used for the cam and governor gears, the engine
frame pieces, the cylinder top, brackets and other small parts.
12 November 2013: Over the last couple of days, I've been working on parts for the governor.
Schematic of Governor
think this drawing will show the general operation of the governor.
The left part of the drawing is an elevation view of part of the
engine showing the governor and associated linkage. On the right
is a plan view with the governor weights all the way out. As the
engine speeds-up, the governor weights move out, pulling on the links
which connect to the spider that is attahed to the governor rod.
As the engine speeds up, the governor rod moves to the right. This causes
the arm, which pivots in the midle to rotate clockwise around the
center pivot (not shown). The other end of the arm supports the
middle of the intake bellcrank and moves it to the left, away from the
engine and the intake valve moves with it. The end of the
bellcrank opposite the valve is connected to the intake eccentric.
When the bellcrank moves away from the engine, the valve moves
with it making the intake slide valve open less at the end of it's
stroke. This should provide throttling.
13 November 2013: While awaiting the waterjet cutting, I made the crank pins.
Crankpins are made.
my usual practice, I'm making the crankshaft extra-heavy duty.
The pins are one inch in diameter. The main pins are made
of steel shafting and the crank pin is a hard steel dowel pin.
The finish on the shafting and the crankpin is good enough that I
won't have to do anything to them in the lathe. Once the
crankshaft is finished, I'll shave the gib keys to fit. Right
now, they're a bit tight.
Bellcranks coming along.
bellcranks change the near vertical motion from the eccentrics to
horizontal motion for the valves. As I explained before, the
exhaust bellcrank has a solid mount to the engine frame while the
intake bellcrank mounts on the bottom end of the governor arm.
The opposite end of the bellcrank from the valve connects to the
14 NOvember 2013: I've
been spending a lot of time making the bellcrank parts. One more
flat part is needed then I can weld the arms and clevises together.
More of the bellcrank parts.
of the time consuming things to make are the clevises. They are
made of .375" steel 0.375" wide and 0.5" long. Four of
them have a 0.125" slot milled in them to accept the links.
Milling that slot 0.375" deep is really boring because the feed
has to be very slow to keep from breaking the end mill. The
fourth clevis is 0.625 long and has to have a 0.500" slot milled in it.
clevises with the 10-32 threaded end will screw into the slide valves.
The screws can be run in or out of the valves to make fine
adjustments to the ends of stroke. Note that the clevises for the
valves use a shoulder screw instead of a 0.125" Dia. spring pin to
connect them. This is so the screws can be removed, disconnecting
the link, to turn the clevises.
sure you've noticed that I mark-up my drawings as I go along and find
"Aw-Shoots" when making parts. This is in keeping with my shoddy
16 November 2013: The bellcranks and the exhaust bellcrank pivot stand are done.
The bellcranks and the exhaust bellcrank stand.
ahead and give me a hard time about my welding. I know it's ugly
and takes a lot of grinding and filing to get these to look even
decent. If I had the bellcranks to do again, I think I;d make
them out of solid, one piece. That would eliminate having to
expose my welding skills. Note that the two photos on the right
have been flipped to show them in the position they'll be in on the
engine. The valves are connected to the two studs. The
intake bellcrank pivots on an arm from the governor.
is made out of a 5" length of 3" steel pipe. All that needed to
be done was to face it off to exactly 5.000" then clean up the outside
diameter and the part of the inside diameter that has to mate with the
head ring and base plate.
18 November 2013: Today, some more of the governor parts got done.
Governor gear-end bearing.
thrust bearing and housing.
governor gear end bearing is composed of two ball bearings in a housing
that is to be pressed or welded into the frame of the engine. The
1/4" diameter pushrod goes through the 1/2" governor shaft and across
to the opposite engine frame where there is a thrust bearing that
connects to the governor arm that goes down to the intake valve
Governor pushrod assembly so far.
the bearings I'm using are not sealed or shielded, I've improvised.
On the gear end bearings, I made shielding washers out of 0.005"
shim stock. On the thrust end, I'm using a piece of vellumoid
gasket material cemented to one end of the housing and will simply
stick some cellophane tape over the other end. I think that these
shields should keep the dirt out of the bearings.
Governor spring, housing and base adjustment washer.
last item I made today is the governor spring, housing and the washer
that engages with the speed adjustment bolt, The spring housing
engages the governor arm close to the pushrod thrust bearing. At
the center of the governor arm is a pivot that reverses the motion to
properly control the intake slide valve. (says here in the fine
I'm still waiting for the shop to give me a quote on
the waterjet cutting. This is why I'm making everything I can
before getting the waterjet cut parts. Pretty soon I'm gonna run
out of stuff to make!
20 November 2013: I got the slitting saw and arbor yesterday so I could finish the governor spider and weights.
Sawing the link slots.
Spider with links in place.
really not impressed at all with some of the Chinese tooling that is
being sold. The slitting saw has about 0.005" of runout.
I'm not sure whether the runout is in the saw blade or the arbor.
In any case the "Zzzzitttt-Zzzzzittt-Zzzzittt" sound of the saw
running is irritating. Oh, well - the slots got cut.
links are held to the spider and weights by 1/8" spring pins. The
weights cannot be attached to the links until they are inserted in the
governor housing so I just show a punch temporarily holding one of the
weights to a link.
What I had to use.
lathe being turned.
tour of the scrap yard to get steel, I stumbled upon a piece of 3"+
shafting that I figured I could use for the governor housing. It
was really dirty and rusty and I found out why it was in the scrap yard
when I started facing one end. There was a spot that didn't want
to clean up. Upon closer inspection and probing with an old
hacksaw blade, a deep cut was exposed in the piece. I don't know
how this happened but it sure made the piece useless for anything.
"B" was to cut the last of the "blocks" I got a year or so ago at the
scrap yard. There was a large number of them so I grabbed a
half-dozen or so. I should have gotten a lot more because I
haven't seen them again. Anyway, in addition to sawing the excess
off and turning it round, I had to face off about 1/2" from the
thickness before boring it out.
The semi-finished governor housing.
that's left to do to this part is to bore the four weight holes and the
four mounting holes. This part bolts to the governor gear.
The spider is in the center and the weights run radially out from
the center of the housing.
The final assembly
of the governor weights to the spider wasn't easy. You can see
that I had to mill radial slots so the links would clear after assembly
as the weights were spread and the spider was pushed away from the face
to make the links swivel toward the back. I'm not really sure if
this governor design will work well but the only way to tell is to get
the engine finished and give it a try.
24 November 2013: The valve eccentrics were next. They are made from a hunk of 2.250" diameter round bar stock.
The eccentrics and bearings so far.
was a lot of whittling done today. I've still got to finish one
of the eccentrics, make the eccentric retainers and the eccentric big ends
that the bearings fit into. These parts should be complete within
the next couple of days.
26 November 2013: The second eccentric and the eccentric retainers are done.
One of the eccentrics and it's retainer.
I thought I had some 1/4" hot rolled steel flat stock.
Looked all over and all I had was some 5/16" HRS so I "converted"
it to undersized 1/4" for the eccentric rods. The "converting"
was done by flycutting in the mill. Not too elegant but it works.
In any case, even if I'd had 1/4" steel, I would have had to
flycut 0.012" from the thickness so I really didn't waste much time
with that part.
"converted" steel for the eccentric rods.
Boring the eccentric rods for the bushings.
eccentric journals are 0.250" wide and the bushings will be around
0.248" wide or so. The eccentric rods will be 0.238" wide so the
bushings will stick out about 0.005" on either side of the rods.
This will allow for a bit of a thrust bearing surface.
you may note, the rods are stacked and clamped to the face plate so I
can bore both of them together. On the eccentric bearings, I plan
for slightly less than a press fit so I can use bearing set LokTite and
be able to move the bearings to center them in the rods.
30 November 2013: With sore fingers, I type this entry. Oh, yes - the valves are done.
out on the scrapyard brass.
Cutting and milling the
valves to size wasn't that difficult. The hard and bloody part
was lapping them flat. Starting out with 320 emery paper, they
were gotten to within a half thousandth of the same thickness then were
fine lapped with 400 paper. The edges got sharp as they were
lapped and I got a few little cuts. I could have used gloves but
wouldn't have been able to feel what I was doing.
1 December 2013: I'm still finding more parts to make.
The governor crank connects
the governor to the intake belcrank.
Showing how it works.
governor crank connects the governor rod to the intake valve belcrank
It pivots in the middle. The governor spring also connects to the
governor crank. In the right hand photo above, I've hung the
parts together to give you an idea how it works.
top is the thrust bearing that connects to the governor rod. As
the engine speeds up, it pulls the top of the governor crank toward the
engine frame. Just below the thrust is the governor spring
socket. Just below the governor spring socket is the governor
crank pivot that mounts to the engine frame. Because of the
pivot, as the engine speeds up, the bottom of the governor crank moves
the intake belcrank away from the engine frame, causing the intake
valve to open less at the end of it's stroke (to the right is full
open). The center pivot of the intake valve belcrank connects to
the governor crank. The upper pivot of the belcrank goes to the
intake eccentric where downward motion moves the valve to the left.
The eccentric rod connectors.
couple of small parts were made. These are the swivels that will
be welded to the intake and exhaust eccentric rods. Right now,
I'm not sure if I'm going to go out and buy some 1/8" X 1/2 spring pins
or just make the pins out of 8-32 machine screws. It'll be easier
to take these joints apart with the screws.
don't know how to explain how this works. The eccentrics are at
the top and run off of the half-speed timing gear. The eccentrics
are both shown in the valve closed position. You can see that the
exhaust belcrank is fixed to the engine frame while the intake valve
belcrank is attached to the bottom end of the governor crank. I
think the operation will be obvious once I have the engine built and
can slowly turn it to show how everything works (OR is supposed to work).
may have to design the mixer and ignition for this engine before
building the frame and valve body. This is because I haven't
gotten a quote on cutting out the parts, much less having the parts on
As I said earlier, I'd like to run this engine on propane
so I guess I'll have to round-up a small demand regulator. The
regulator will probably be bigger than a model engine uses because this
engine is a bit over 4-1/2 cubic inches in displacement. Not
having any practical propane fuel experience, I think I will need to
have some restriction in the air inlet so the engine will develop some
intake vacuum in order to operate the regulator. Some study is
definitely in order.
6 December 2013: With
nothing else to do while awaiting the cutting estimate, I've decided
that I can go ahead and make the blanks for the crankshaft and governor
gears. The governor gear major diameter is 1.375" (20 teeth) so I made the
blanks out of 1-1/2 bar stock. The crankshaft gear blanks will be
made from 2.250 bar stock.
Governor gear blanks.
The reason I'm making two blanks for each gear is in case one of them gets messed-up.
I'm still waiting for a quote on getting the steel cut. This is getting boring.
the meantime, I designed a demand regulator for the LP fuel system for
the engine. The design is mostly guesswork along with some CAD to
make sure everything got connected inside the housing. The
diaphragm is made from what I had on hand, some rubberized fabric I
used to rebuild the fuel pump for the Stover DV-2 engine. It's a
bit thick but may work. I had no luck finding any rubberized
diaphragm material thinner than 1/16". I dunno where the
rebuilders get the 0.015" stuff but I can't find any.
Exploded view of both sides of the demand regulator.
regulator consists of a needle valve at the inlet (the one with the
packing nut) that feeds gas to another needle valve which is operated
by the diaphragm. The chamber at the top of the diaphragm is
connected to the throat of the mixer "downstream" from a venturi
restriction. The other side of the needle diaphragm is vented to
the "upstream" side of the venturi restriction (carrying fuel to the
throat), causing a differential pressure across the diaphragm during
the intake stroke. The suction of the engine operates the
diaphragm to raise the needle valve. There's another adjustment
on the opposite side of the demand regulator from the inlet needle that
squashes a compression spring that is balanced by a lighter spring on
the needle side.
In operation (AND, in theory), engine
suction will raise the diaphragm to let in fuel. The more the
intake valve opens, the more suction is developed and that raises the
diaphragm and needle higher to allow more gas to flow to the mixer
I think that, in operation, the diaphragm needle spring
adjustment will be a sort of idle setting and the inlet needle valve
will determine the maximum amount of gas to be delivered under load.
Clear as mud, eh?
Whether this works is to be determined. In any case, it sure looks clunky, made of two 1" thick aluminum pieces.
The fuel system.
finish off the fuel system, I dug-out a tank regulator and hose from a
defunct gas grill. I made a fitting to adapt the burner fitting
to a barb so I could extend the line.
16 December 2013: Having
nothing better to do today, I took another look at the mixer and
thought it looked more like an aluminum brick than what it really was.
I spent about half a day "improving" it.
19 December 2013: FINALLY! The
steel parts are cut. I had to have them plasma cut because I
couldn't get the shop with the waterjet cutter to quote on the job.
Plasma cut parts.
plasma cutter seems to have done a good job on the 1/2" parts but I
think the 1" parts were about at the machine's limit. I'm glad I
made the CAD cut file with everything oversized and undersized.
In spite of the roughness of the 1" parts, there's enough meat
left for me to be able to clean them up and get them to size.
number 3,582: Don't try for small holes in thick parts with
plasma. I should have left the holes out of the crankshaft cheeks
and main blocks. It's gonna be pretty noisy cleaning the bores.
I just hope the steel didn't harden along the cutlines. If
so, I'm going to have to get some carbide milling cutters.
larger two circles are for the eccentric (60-tooth) gear blanks.
They'll get machined so I can get them in the UPS truck with the
other two gear pairs to go to Iowa to be hobbed.
21 December 2013: Yesterday, I got the 60 tooth gear blanks finished and today I sent them on their way to Iowa.
I started on the crankshaft and discovered that one of the mainshaft
bores wouldn't clean-up. Off to the 'ol buzz box to add about
0.050" of metal where it was shy then back on to the lathe for
finishing. The other cheek was in better shape but still had a
slight void when I got the bore to press-fit dimension. I've
sized the pin bores between 0.001" and 0.0015" smaller than the shafts
for a tight press fit.
Then, after getting the main bores
finished, I made a locator shaft that is a very light press fit in the
bores. I shrank a collar onto this shaft so I could hold the two
cheeks together for turning the O.D. of the counterbalance.
Turning the O.D. of the counterweight portion of the crank cheeks.
operation took a while because my little lathe could only take off
0.010" per pass. You will note that I've jury-rigged a
counterweight so the whole works wouldn't make the lathe dance all over
the shop. After they were turned and deburred, the counterweights
were removed and the works was set into the mill.
Centering the main bearing bore in the mill.
mounting the cheeks in the mill, I banged them as close as I could get
them to square and true. There's enough meat to get them set
close enough to be able to locate the crankpin bores and mill the rest
of the flat surfaces.
Using the collar on the shaft which was
turned concentric to the shaft, I used my handy-dandy orbital centering
gauge to easily find the exact center of the bore. Tomorrow, I
will step-off 1.250" to the center of the crankpin bore and get it
done. In the same setup. I hope I'll be able to mill the rest of
the vertical flat surfaces of the cheeks to size.
23 December 2013: Today, I finished the crankshaft.
Cleaning up the outer surfaces.
Getting ready to
sure got a bunch of dull end mills. It took the better part of
the day to clean-up the surfaces and press the shaft together.
first thing done when assembling the crankshaft was to press the
crankpin into one of the cheeks. As you can see in the right
photo above, I used a locating pin that is a light press fit in the
main bores. This aligns the cheeks to be in line when pressing
the pin into the second cheek. After pressing it together, the
alignment pin is removed and the main shafts are pressed in. A
spacer as wide as the rod journal is used under the mains between the
cheeks when pressing the shafts on.
Finished crankshaft with mains and flywheels temporarily in place.
putting the crank together, I put it between centers in the lathe to
check straightness. It was out about 0.015" in the middle as
referneced to the ends. I put it in the press and got the
straightness to less than about 0.005". I didn't want to move it
too much because the crankpin is a hardened, ground and polished dowel
pin and I was afraid it would snap.
The balance of work needed
before the crankshaft, flywheels and mains can be finally assembled is
to dress-up the gib keyways so the keys aren't so tight. Note
that the key is sticking out so far not because it's vertically tight
in the taper but the keyway in the crankshaft is just a tad tight so
some filing is in order.
Since I'm feeling charitable, I'm
giving the entire staff and management of Hoyt-Clagwell & Company a
couple of days off to enjoy Christmas.
27 December 2013: Yesterday
and today were spent cleaning up what I call the base of the engine.
Actually, it's the head but, since it's my engine, I'll call it
what I want! This is one of the more complicated parts.
combustion side of the base.
The valve side of the base.
blemishes in the faces of the steel base won't affect the engine.
On the combustion side, there will be a 1/8" deep "donut" bored
to seat the liner and water jacket. Also, the head bolt holes
haven't been drilled and tapped yet. I'm going to have to set-up
the rotary table to step those holes off and I want to get the top of
the cylinder (crankshaft end) header done so they can both be done in
the same setup.
In the right-hand photo above, the 0.032" deep
milled area is to fit the 0.0625" PTFE (Teflon) sheet that will be the
valve seal for the upper side of the valves. Since it can
withstand 600F and is self lubricating, I hope it will work with the
The spark plug, located in the intake passage.
the photo avove, you can see the spark plug peeking into the intake
port. This is on the combustion side of the valve and should work
fine because it is right in the gas flow.
28 December 2013: The
base and cylinder top are almost completed. First, I mounted the
base on the face plate for turning the grooves for the liner and jacket
to seat in. When I put the face plate in the lathe, I found that
the base is about 1/8" too big diagonally to miss the ways. Scrap
Plan two was to go ahead and put the rotary table
back in the mill. The table was centered then the base was
clamped to the table and it was centered. I stepped-off the
radius of the O.D. of the jacket and added half the diameter of the
1/4" end mill plus some slop and cut the 1/8" deep track for the
jacket. I did the same thing with the cylinder except I set up
for the I.D. of the bore so it would seat in the base with a light
Milling the seating grooves for liner and jacket..
I had the base on the rotary table, I drilled the five bolt holes which
will be tapped for the 1/4-20 hold-down bolts. These holes don't
go all the way through the base because first, they really don't need
over about 5/8" of thread and if they don't go all the way through,
there is no chance of leakage. These holes still have to be
Base with grooves milled.
Liner in place.
jacket and cap in place.
cylinder cap could be done in the lathe and will also be put on the
rotary table so the five hold-down bolt clearance holes can be drilled.
fits are all light press fits except for the jacket where it seats in
the base. I allowed clearance here so any misalignment of the
liner would have some place to compensate. Because of the fits, I
will simply use silicone gasket compound on all but the jacket to base
joint and may go ahead and use it there, too. Everything is sized
so that it all seats when drawn-up. I may simply make some copper
washers to seal the bolt heads in the cap.
All done except for the bolt holes in the cylinder cap.
getting the cap drilled and the base tapped and before assembling these
parts, I must remember to drill and tap the jacket for the water inlet
and outlet. They will be 1/4" pipe. The inlet will be low
on the jacket to the left in the above photo and the outlet will be
high on the right on the jacket in the above photo.
drill and tap the cap for a 6-32 screw which will clamp the oiler
tubing for the cylinder. There's enough chamfer in the cap and
cylinder to guide the oil to the piston skirt. I assume enough
oil will be slopped around there to lube the wrist pin. If
nothing else, I guess I could stick a wad of cotton down in the piston
and keep it soaked with oil.
29 December 2013: The base, liner and jacket are done and assembled.
Base, liner, jakcet, etc assembled.
yes. I did remember to drill and tap for the water inlet and
outlet and for the screw to hold the oiler line. Yesterday, I got
some 1/2" galvanized pipe to make the legs from. They will hold
the engine up off of the skid by about six inches.
I decided to go ahead and make the skid for the engine. I guessed
how big the cooling tank was going to be but I'll probably just make
one up that fits. Tomorrow comes the sanding and first coat of
paint. Color? Your guess is as good as mine. I'll use
whatever color I have enough of to do the job.
30 December 2013: I've
got some paint on the skid. The color I picked was some Rust
Oleum oil base grey that had been sitting on the shelf for a while and
I figured it was a good time to use some of it.
I made the stand columns for the engine. I faced to length and
bored out the 1/2" galvanized pipe so I could press some
turned-down 1/2-13 nuts into them. Then I made four big 1/8"
thick washers to keep the columns from sinking into the skid.
It's sort of starting to look like it may turn into an engine.
1 January 2014: Since the paint dried on the skid, I did a test fit of what there is of the engine on it.
Finished skid with engine on it along with the cleaned-up and painted flywheels.
I didn't want to have to fiddle with the big washers every time I
mounted the engine, I glued them to the skid. Same thing on the
washers on the bottom.
The flywheels got stuck in the
mill and turned true then cleaned-up and painted. The paint I
used was some acrylic lacquer that I had left over from painting the
'50 Chevy. I knew I'd need it again. Nice thing about the
acrylic is that it dried really fast, even when brushed on.
started on the valve plate and mains but had to stop and wait for the
new 7/8" carbide insert mill to arrive in order to clean the parts up.
3 January 2014: The
carbide insert end mill finally got here late this morning so I got
back to work on the mains. Over the time I've been building these
engines, I think I'm finally getting to where I have a system of
machining split bearing blocks. The photos below will explain the
process. Note that the blanks are really grungy, especially the
bores! They should clean-up fine for the bushings.
Find the squarest
Belt sand to even surface.
Sanded reference surface ready for
Side opposite reference
reference side to dimension.
Rotate 90 degrees and clean both surfaces
Divide by two.
Mark for bolt holes.
Drill bolt holes.
Saw along midline.
Mill mating surfaces to dimension.
the cap blanks are first checked with a square to find the best
reference surface. Then, that surface is belt sanded just enough
to lay flat. The blank is set into the mill vise with the belt
sanded (reference) surface down and the opposite surface is cleaned up
with the flycutter. After deburring, the blank is turned 180
degrees in the mill vise so the reference surface is up. This is
flycut to dimension.
The blank is then laid on it's side,
clamped in the vise on the previously sized surfaces and an end mill is
used to just clean these surfaces. The dimension will be
oversized enough to be able to saw cut and then mill the parts to
Now, the cut line is made one half of the unfinished
dimension of the blank and the bolt holes are laid out for drilling.
Before cutting, each of the blanks is set in the mill and the
bolt holes are accurately laid-out, spot drilled, undersize drilled
then re-drilled to size (in this case 1/4").
After drilling the
blanks, they are cut in half. The next to last part of this
operation is to put the caps in the mill and mill the sawed edges clean
and to dimension.
Tomorrow, I'll mill slots in the
bottom surfaces of the bearing blocks that will fit over the engine
frame and assure alignment. There will be 6-32 holes drilled and
countersunk in the centers of the bottom halves of the main bearing
blocks for holding/locating screws into the frame. The bearing
bolts clear through the bearing blocks and thread into the frame.
bearing bore will not be done at this time. It will wait until
the frame is prepared. Then, after locating the bearing blocks on
the frame, drilling and tapping the locating holes and bolt holes, the
bearing blocks will be bolted to the frame. At that time, both
frames will be laid together on the mill and and registered. Then
the bearing bores for the mains, eccentric shaft and governor will be
drilled and bored. Finally, the "feet" of the frame will be
milled to dimension and the other surfaces will be cleaned up.
4 January 2014: The main bearing blocks now have their groove milled to fit snugly into the tops of the frame plates.
Main bearing blocks ready for installation in frame plates.
I got a good start on the valve plate. This part bolts underneath
the engine base and registers with the intake and exhaust ports.
Between the base ports and the valve plate are the intake and
exhaust slide valves.
milling pass on valve plate.
Test fit of valves.
There will be another
milling operation on this side of the valve plate. This will be
an 0.032" deep pocket as wide as the valves but allowing 1/8" lip at
the ends (the plane of the valve motion). This depression will
contain a fitted 0.0625" thick sheet of Teflon. There will also
be a sheet of Teflon on the upper side of the valves, also held in a
pocket in the base. I'm hoping the Teflon, which can withstand
600F will make a good lubricating seal for the valves. I don't
think there will be any problem with the sides of the valves rubbing
because there is no side thrust on them.
5 January 2014: The valve plate is finished and has been assembled to the base.
bearing sheet in valve plate.
Valves in place.
bearing sheet in base.
valve block will have to be removed to bolt-on the frame rails but I
found that the hold down bolt tightness is very touchy. Once a
little drag is felt in the valves, any more tightening causes the valve
action to get really stiff. I may have to put some compression
springs on the bolts to make the pressure easier to adjust.
bearings with bolts.
Starting on the frame rails.
While I was making the valve plate bolts, I went ahead and made a set of high-crown bolts for the mains.
I put the frame rails in the mill and squared them up. I found
the rough center of the governor bore and bored it just enough to
clean-up. This will be my interim reference for boring the shaft
holes. One outside vertical surface is cleaned-up and the base of
the mains is milled to dimension. That is where I stopped for the
After milling the other outside vertical surface and the
"feet" where they bolt to the base of the engine, the rails will be
removed from the mill and the mounting and main bearing holes will be
drilled and tapped.
6 January 2014: Today
I got the frame rails milled to size and the mounting holes drilled and
tapped for the mains and to hold the rails to the engine base.
A neat way to scribe an accurate line using the mill.
I was working on the frame rails, I was trying to figure out how to lay
out the mounting holes to the frame and for the mains. What I
ended-up doing was to accurately find the center of the governor bore
then crank the table to the vertical centerline of the rails.
Then, I used a punch in a collet to make punch marks for a
vertical center reference. While still held in the center
position, I put the centerpoint feeler to the coaxial center finder in
a collet and positioned it exactly on the centerline punch mark.
The centerpoint feeler has a hardened point and is spring loaded
so, I could use it to make a line in the Dykem bluing.
lowered the knee (so the point wouldn't touch) and moved the table to
about an inch below the position of one of the main bearing bolt holes
and again dragged the feeler to the edge of the frame rail. I did
the same thing for the other main bearing bolt hole and the holes to
mount it to the base. While everything was still in the mill, I
blued the faces where the holes were going to be drilled and then,
unsing a square, scribed lines from the locating lines down the faces.
removing the frame rails from the mill and deburing them, I scribed
lines down the centers of the bolt hole faces and center punched the
locations for the holes.
in the vise for drilling.
Mounted to the base and mains bolted down
and pressed to the frame rails.
the frame rails in the drill press vise, the holes were drilled and
tapped a few turns in the mill to make sure they were square.
After finishing the tapping, the rails were mounted on the base
and the mains were loosely bolted to them for alignment. The main
bearing blocks were pressed onto the frame rails. Since it took a
couple of tons to press the mains onto the frame rails, I think they
will stay put while the bolts are out for mounting the crankshaft so I
didn't drill and tap for separate hold-down screws.
Next up is
to lay the rails back together in the mill with appropriate spacers and
bore the mains to size. I don't have the gears back so I'll
double-double check the calculated center distances and go ahead and
bore the eccentric shaft and governor holes along with the governor
spring tensioner spring and governor arm mounting holes.
7 January 2014: Geez!
I had a really good time today getting the frame rails with the
main bearings on them lined-up in the mill to do the bores for the
mains and the gears.
Doing the main and gear bearing bores.
you can see in the photo above, in order to lay-up the parts, they had
to be spaced off of the mill table and separated. Getting it all
squared-up was a real challenge! If I got the bottom rail all
nice and square, the top rail would be out of kilter. It seemed
that, no matter how carefully I bumped the top rail to get it to
register with the table and the bottom rail, it would screw up the
bottom rail alignment. After an hour of piddling with it (and
doing a little cussing) I finally got it nailed down.
"aw-shoot" was the hole for the governor shaft bushing. The
cutting process made this hole too big to be cleaned up at dimension
(0.375" diameter) so I bored it to 0.625 and will make a bushing to
press the bronze bearing into and press the bushing assembly into the
In this setup, I'll also drill the holes for the
frame rail spacers. I decided to add these because the rails were
tipped together about 0.005" at the top and I decided that the spacers
would correct this and would add a little stiffness.
still have the final fitting of the mains to do. I bored the main
bearing blocks to the specified O.D. of the bushings. Since the
bushings are designed to be a press fit, I'll have to turn the bushings
to fit. Also, the thrusts are somewhat tight so I may put
the crank up in the lathe and skin it to gove a couple of thousandths
One minor aw-shoot was the 1/2" mounting bolts for
the base. When I cleaned up the sides of the frame rails, I only
took off enough to clean them up. That made the outer edges of
the hexes interfere with the frame rails. That was fixed by
simply turning 0.030" off of the hexes. While I was at it, I
faced the heads of the bolts to get rid of the factory stampings and
give a nice slick finish.
9 January 2014 :It
took a while but I've now got the mains semi-fitting. I turned
the O.D.s of the main bearing bushings until, as I tightened the caps,
they had a lot of drag. Then I loosened the bolts until the
crankshaft turned fairly freely.
Motoring the mains.
I fitted the gib keys and gtemporarily mounted the flywheels so I
could hook up the motor to run-in the mains. After three
hours, it's still very tight so tomorrow, I'll take it apart and check
to see where the wear is occurring. Based on what I find, I will
either turn another thousandth or so off of the bushings or will use
the TimeSaver lapping compound to get a fit between the bushing and the
While the motor was doing it's thing, I made a couple of grease cups and called it a day.
10 January 2014: I
ended-up turning a couple of thousahdths off of the O.D.s of the
bearings. They were still too tight to snug down the bearing caps
without heavy drag so I loosened the caps enough for the crank to turn
fairly easily, started the motor and put a few drops of oil whth some
fine TimeSaver soft metal lapping compound mixed in. At first, as
the lapping compound worked it's way into the bearings, the motor
labored a little more. After a minute or two, the laboring went
away and I slowly tightened the caps, adding more of the oil/compound
until the bolts were just snug. At that point, I quit adding the
oil/compound and just added oil until the crankshaft was almost turning
Then, I removed the belt and removed the crankshaft and
cleaned the bearings and the shaft. After putting it back
together and using oil, the botor labored a little with the caps almost
tight. After about a half hour, I could fully tighten the caps
and the motor was only slightly laboring. I let it run on the
motor for about another hour and it hadn't loosened-up appreciably and
were running just slightly warm, so I think the mains are good to go.
the motoring was going on, I started on the connecting rod. The
usual milling cuts were made to clean up the torched surfaces.
Using a steel rule, I measured the distance from the punch mark
in the center of the wrist pin bushing area and added a few thousandths
to compensate for the saw kerf. With this line drawn, I drilled
and tapped for the rod bolts. Then, the cap end of the rod was
sawed-off. The cap was set-up in the mill vise and the mating
surface was milled flat.
Then the rod was put in the mill vice
and squared-up again. The center punch mark in the center of
wrist pin end of the rod was used as a reference and the mill was
zeroed over this mark using the coaxial center finder. I don't
know how I would get along without that thing. It really makes
finding the center of either a bore or a punch mark easy.
the wrist pin end was drilled and reamed to 1/2" for pressing-in the
wrist pin bushing. This will be done tomorrow and I'll probably
have to put the rod back in the mill, find the center of the bushing
and ream it to fit the wrist pin after it's been squashed from the
I then stepped-off the 7-1/4" to the big end, adding
the radius of the milling cutter I'd mounted. This was used to
clean up the mating surface to the cap on the rod and finish the
effective length dimension. A shim pack was made using two 0.002"
shims and one 0.001" shim in each side and the rod cap was firmly
Then, I stepped back the radius of the cutter and,
using a series of bits, drilled the rod bearing bore to 3/4", the
biggest bit I have. An enjoyable hour or so with the boring head
to get the diameter up to 1.250".
The rod, ready for bushings.
The rod bearing has yet to be made. That's for tomorrow.
11 January 2014: After
a lot of time in the shop, I now have the rod bearing made and the
wrist pin bushing pressed-in and reamed. It doesn't seem like a
lot was done but the rod bearing was tedious. Here's a photo
spread to show how I split and turned the bearing.
Cut off the blank and mark for split.
Saw blank in half.
Finished split blanks.
soft soldered together.
Mounted in 4-jaw and I.D. bored.
Fixture for turning O.D.
bearing, still in one piece.
Bearing sweated apart.
Bearing in rod.
you can see, it's not a simple task to split a bushing and end up with
round and correctly sized I.D. and O.D. There must be an easier
way to do this but I haven't figured it out yet. On my other
engines, I got the split bearings sized and fitted okay but wasn't
happy with the process. This method eliminates the large gap
between the bearing halves that had to be filled with a thick shim.
Rod, marked for clearance to cylinder and piston skirt.
thought I was going to get the piston in the engine and hooked to the
crankshaft but I have clearance problems and will have to do some
whittling on the rod and possibly the piston skirt. I was kind of
expecting this because the rod was way oversized for the plasma cutting
and I just cleaned up the surfaces, not worring about dimensions.
I should have worried about the dimensions because I now have to
do a bunch of whittling to get it to size.
12 January 2014: I got the rod trimmed to closer to what the design calls for.
The almost as-designed connecting rod.
kind of obvious that I left the little end fat for a distance instead
of making a bulb for the bushing. The reason for that is, if you
look carefully, you can see where I milled a near vertical slot with a
hole connecting with the wrist pin bushing. This is for oiling
and I wanted it to be sure to catch oil while the engine was running.
Then, I put it all together andWE HAVE RECIPROCATION!
Motoring with piston and rod in place.
the rod misses the end of the cylinder and piston skirt by just a
little, it's enough. If I decide I need more clearance, all I
have to do is increase the radius on the corners of the rod.
took a few cycles of disassembly, scraping and filing to get the rod
thrusts trimmed so they didn't bind. While it was motoring, I
made a grease cup for the rod. After motoring it for an hour or
so, it's almost turning free. While it was motoring, I moved the
valves to the closed position. There was a little leakage around
the exhaust slide but a slight tightening of the valve plate remedied
that. The valves operate without a whole lot of drag and the
piston seals well enough that I can's hear any blowby when the valves
are closed. I still may have to make another piston and use
regular cast iron rings but I'm hopeful that the Teflon rings will
14 January 2014: Today,
I started on the eccentric shaft and governor. Immediately after
reaming the bushings and slipping the eccentric shaft into olace, I had
the first "aw-shoot!" of the day. The rod interfered with the eccentric
shaft. That got fixed by turning the diameter of the shaft down by
0.100" where the interference occured. Then, I removed a bit from
the rod for insurance.
Eccentric shaft necked-down to clear rod.
I mounted the intake eccentric on the shaft and started fiddling with
getting the governor to be polite to it. After a couple of hours
of bending, cussing and milling, I've got it close to near ready.
In the course of things, I found that the eccentrics interfere
with the governor arm. Nothing to do but to shave on the intake
eccentric. I'll have to do the same thing with the exhaust
Intake eccentric and governor rod.
in all, a semi-frustrating day. I should have worked the CAD a
bit more and done an interference study and I could have saved myself
15 January 2014: I -think- I've got the valve linkages in shape.
Valve gear in place.
won't be able to accurately time the valves until I get the timing and
governor gears. Right now, I have them set so there is just a
slight amount of overlap but have no idea if the durations are even
close. At least all the linkage has now been tweaked until there
is no binding.
Since the intake valve is controlled by both the
intake eccentric and the governor arm, there are things coming from two
different angles so a bit of bending and added clearance was added.
also got the water piping done. The cooling tank will consist of
a couple or three institutional tin cans soldered together. I'll
throw on a couple of coats of paint but if the cans rust out, I can
always whip something else up.
20 January 2014: I finally got back to the engine. Today, I woeked on the cylinder oiler.
The partially completed cylinder oiler.
cylinder oiler will mount to the engine frame and will supply oil to
the top of the cylinder via a short length of 1/8" copper tubing.
The cooling tank is awaiting the arrival of the second institutional peach can. We can only eat peaches so fast, you know.
the meantime, while adjusting the float voltage on my Sola 800 Watt
Uninterruptible Power Supply, I dropped the screwdriver and it landed
on the circuit board, causing the magic smoke to leak out of a voltage
regulator and a big transistor. That little fixit job will take
some time because I cannot get a schematic for the UPS and, if
replacing the VR and the transistors don't fix it, I'm in for a "voyage
of discovery". That'll teach me to be clumsy!
24 January 2014: Not making a lot of progress lately but do have two items more or less finished. First, the oiler.
Cylinder oiler mounted on engine.
think the cylinder oiler will work as I've got it. You'll notice
in the photo that the outlet from the oiler goes through a piece of
1/8" copper tubing and exits right at the edge of the cylinder so the
oil will run down the ring chamfer. The filler plug is made from 1/4"
brass bar stock and the retainer is a piece of nigh tensile
multi-strand wire from some long-dead thing. The fill plug
retainer is made of stainless and is staked into a hole in the bottom
of the plug. I had trouble filling the oiler so I may eventually
take it apart and drill a small air hole in the cap. The plug is
a loose fit in the cap so the chamber can breathe.
Cooling tank ready for paint.
finally opened the second peach can so I cleaned them up, soldered in
the inlet (top) fitting and drain. Then I cut most of the bottom
out of the top can and soldered them together. You can see the
hold-down rods on the skid.
I fiddled with the UPS again today
and there is something else wrong beside the voltage regulator and
output transistor. This is gonna be a continuing project because
it's going to be a bear to troubleshoot without a schematic. I'm
determined to "cheat the junk man" on this.
27 January 2014: Over
the last couple of days, I've been doing the fiddly bits.
Yesterday, I made the intake manifold and mounted the gas mixer.
Today, I made the exhaust manifold and exhaust pipe.
Mixer and exhuast in place.
intake manifold was made from a left-over piece of aluminum that is
what was left of the material for the mixer. The exhaust was made
from a hunk of 1" thick steel. You will note that the exhaust
hangs down a little farther than the intake although they are the same
thickness. The reason it is lower is that I made three 0.0625"
gaskets so the exhaust would be spaced 3/16" away from the valve block
for some air circulation.
31 January 2014: Now,
I've gotten everything done I can do before I install the gears.
The last couple of days have been spent getting he ignition
Ignition in place.
I'm using a magnet and a Hall-Effect sensor for the timing. A
plate was made to fit over the thrust end of the gear-side eccentric
shaft. This plate has the Hall sensor mounted on it and can be
rotated about 20 degrees, giving a 40 degree swing in timing. The
magnet you can see stuck to the engine frame below the sensor plate
will be glued to the eccentric gear so it pases the sensor at about TDC
Since I have no idea when the gears will get
here, it's unknown just exactly when I will get them installed, the
eccentrics timed and will try for a big propane explosion.
3 March 2014: In response to requests, here is a sort-of update.
it's been a cold winter in Iowa where the timing gears are to be made.
The volunteer for the job says he's doing a LOT of overtime at
John Deere and it's been cold enough to freeze the bugs but he still
plans to make the gears. I guess we should all be patient.
looks like this is yet another engine that I get to test outside in the
summer in Florida. Oh, well - sweat is good, isn't it?
17 March 2014: Well,
since I don't know when the "volunteered" gears will be made, I decided
to simply do it the easy way and purchase them. When the
"volunteer" gears come-in, I'll save them for a future project.
Today, I made the hub for the eccentric drive gear and milled the keyway in the shaft.
Hub for eccentric gear in place.
eccentric shaft is 0.500" in diameter and the stock bore in the gear is
also 0.500". To have enough meat in the center of the gear for a
proper attachment to the shaft, I made a hub. The bore is 0.500.
The diameter for the gear is 1.000" and the hub is 1.500".
The gear will be mounted on the face plate, registered then bored
so the hub can be pressed into place. A gib key will hold the
gear on the shaft.
I expect the gears to arrive tomorrow evening so I should be working on them by Wednesday.
18 March 2014: Well,
the gears came in this afternoon so I went out into the shop and did a
test fit. I actually got the gear centers correct!
Test fit of the gears.
did goof when I ordered the gears. I thought the gears were
hubless so I made a hub which I don't need. I'll still have to
machine the governor gear and drill it to mount to the governor.
I'll do that later in the week.. I have some "Honey-Do"
projects that must be done before I can go out and play.
All the gears are in, the governor is hooked-up and the valve timing is rough trammed.
Governor gear machined and in place. Here we are, all hooked-up and ready to start cranking.
is the first time I've ever trammed slide valves. It's more
difficult than with poppet valves because you can't watch the rocker
arm for zero clearance on opening and making clearance on closing.
I ended up using compressed air in the intake and exhaust (with
the piston out) to determine when the valves cracked.
is also the first time I've fiddled with a propane fueled engine and
the first demand regulator I've designed and built. It's good
that the weather is nice outside so I can open windows and run an
exhaust fan to clear out the gas (or smoke) when testing.
I'm going to make the first attempts by flipping the flywheels to crank
it. If necessary, I could belt it up but since that's always a
Mickey Mouse lash-up, I'd like to forego it. I may even make a
hand crank handle. We'll see.
21 March 2014: Well
- after hooking up the fuel, ignition, etc. I decided that I didn't
want to crank on the engine so I hooked-up the motor, set up the camera
and made a movie of my efforts. At first, I couldn't make it hit
a lick. Since I could smell no propane in the exhaust, I figured
(correctly) that my demand ragulator wasn't working. I took it
off and re-diddled the balance springs. I put it back on and
resumed cranking. This time I got a few desultory pops out of it.
Struggling to just make a few pops.
then moved the ignition sensor magnet to give about 30 degrees of
timing lead. At this point, it started firing almost regularly
but I still couldn't get it to run rich. This is where I quit for
22 March 2014: Today,
I fiddled with the valve timing a bit, shortening the exhaust duration
and decreasing the overlap to nearly zero. I also found that the
old grill regulator I'm using has a problem. When checking it
using a water column, I saw that it was only putting out about 2" of
pressure. After giving it a couple of love taps, the pressure
rose to about 11" which is about right.
The engine acts like
it's trying to make a little power because I can now feel it "thump"
the base a little while motoring. Now, I'm getting the feeling that the
intake slide isn't opening enough. Although increasing the
opening will necessarily increase the duration, unless I get a better
idea before the next testing session, I'll make the adjustment and see
how it works.
24 March 2014: Progress!
While fiddling with the valve timing, I made a discovery.
When I tetarded the spark to after TDC, the engine backfired
through the mixer. When I advanced the spark, it backfired
through the exhaust.
With a flash of revelation, I realized that
when I placed the magnet for the ignition pickup on the eccentric gear,
I located it to top dead center all right........ Top dead center
on the overlap stroke! DOH!
When the magnet was moved to
TDC on the compression, the engine actually made some noises like it
was trying to wake-up. Before I could get it tweaked to where it
would run off of the belt, the Teflon piston rings gave-up. It
may be because they need to have expanders behind them.
What I may do is to just order regular cast iron rings and make a
new piston. We'll see.
30 March 2014: In
the last few days, I've been trying to get the engine to run. A
couple of days ago, I removed the piston and checked the Teflon rings.
Teflon rings after they failed.
you can see in the photo above, blowby darkened them and they are
chipped. I still think Teflon (PTFE) could be made to work for
piston rings but, so far, haven't found the secret.
Ring groove modified for the Buna N ring.
the groove isn't what you'd call a standard shape but I had machined it
for two of the Teflon rings in the same groove. The new material
is designed for "O" rings and is bought by the foot. As you can
see, I've given it plenty of width clearance. I cut the length so
that the ring gap is tightly pushed together when the ring is in the
cylinder. The groove is about 0.020" deeper than the ring to
allow for gases to get behind it and push it toward the cylinder bore.
I put it all together and again motored it. This time, it
actually made smoke. It ran well enough that I could adjust the
fuel mixture all the way through the combustibility range so I know I'm
getting enough fuel for it to run when it finally makes up it's mind to
While motoring it and adjusting the ignition timing and
fuel mixture, I was getting leakage past the slide valves. After
tightening the valve plate so it didn't leak, friction in the intake
setup got to the point where there was a lot of lost motion.
After compensating for this, the intake bellcrank broke so it's
back to the drawing board.
Broken intake bellcrank.
has shown that there is too much drag in the valves to be able to
govern the engine by varying the valve motion so I'm working on
directly driving the intake valve (like the exhaust valve) and, if this
works, placing a throttle plate in the mixer and control it with the
5 April 2014: It's
been a few days since I've updated the page. I made a new bellcrank
stand that eliminated the monkey motion connection from the
governor to the intake valve.
Motoring with the new bellcrank stand.
are still several issues with valve timing I have to address.
That comes tomorrow. Today, though, I got backfire flames
out of the mixer. Oops! I've again got it timed so it fires
the plug on the overlap. I think that after I've fiddled with
this thing enough, I'll get to where slide valve timing will be second
nature like poppet valves are to me now. Tomorrow, if all goes
well, I might actually get it to run a little.
If this iteration
allows the engine to run, I'll use the rev limiter on the ignition
module to kep it from running away until I can get a butterfly throtle
valve worked out and get it connected to the governor.
6 April 2014: After
re-timing the valves, I motored the engine. Now that the valve
timing is right, the valves won't hold. Even with the valve plate
tight enough that the drag is very heavy, when the engine fires, the
combustion gas escapes past the valves. I think it's to the point
where, if it wasn't for the compression leaks, it would run.
going to have to think about the valves. I've got only so much
patience for things like this and think that a major re-think and
re-design may be necessary to get workable slide valves.
the best laid plans sometimes don't work out. This might be one
of those times. It could be that poppet valves are on the
horizon. We'll see.