The Rotary Valve Engine
Non-Rotary Valve Engine Go
the previous pages, I experimented with a rotary valve design.
Although the engine could be coaxed to run and, at times, ran
really well, it was very troublesome to keep running. After
last run, the rotary valves were removed and the seats were found to
have galled, making them unusable. At that point, I decided
I'd proved the point that rotary valves could be done but were not
Since I really want my engines to be able to
run continuously and with little fiddling, I decided to design and
build a new head and use poppet valves and a face cam.
partially completing the new head design, I took a little time to make
up an image of roughly what the new arrangement will look like.
Here's the layout.
a look at what I am working on. Using one of the rotary valve
gears, I will machine the hub into a face cam. There will be
followers, located rotationally 90 degrees apart which share the 100
degree cam. This means that both valves will have the same
duration and will have ten degrees of overlap. If necessary,
can always remove the gear and take some off of the cam.
the duration will automatically reduce the overlap.
pushrods will connect the followers to the rocker arms which will
operate some valves salvaged out of an unknown small engine.
compression ratio will be a bit higher due to the lack of the rotary
valve volumes and the shorter spark plug path. If this proves
problematic, I can always make up a spacer to go between the head and
While working on the new head design,
I decided to find out why there was slight scoring on the cylinder
wall. After removing the bottom plate and piston, I
that I had not machined enough clearance in the ring area of the
piston. I un-hung the piston and turned another 0.015" off of
this area and re-assembled the rod and piston into the engine.
Galled spot on top land of piston before turning.
afternoon, I lost all excuses to start on the new head.
There's a cylinder head in there somewhere.
think the UPS guy is a really good sport. This thing is
It is a hunk of malleable iron that is five inches in
and six inches long. We are getting ready to have fun!
was my day for fighting chatter on my little lathe. At least
turning part of the cylinder head machining is done. Those
0.003" cuts are murder!
Here's the head so far.
next thing to do is to drill and tap the mounting holes for the top
bearing/cam plate in the circumference of the head. After
will work on the top bearing/cam plate and get it mounted to the head.
With the plate mounted, I can accurately square up the two
and do the rest of the machining on the head and plate while in the one
setup. This should insure that everything will fit.
here in the fine
the boring head to match the plate to the head.
Shecking the fit.
Ready for more machining.
you noticed the notch in the aluminum plate, that's where it was
machined before it was scrapped (you use what you've got).
is also a filled bolt hole on the top surface that is just about
invisible. I made a threaded plug, bottomed it out in the
then sawed the excess off and milled it flat.
I will be making a
gear guard out of sheet metal that will wrap around the plate.
This will cover up the bolts and the notch. I know
The plate will remain on the head and all of the machining will be done
with it in place to insure all the parts will fit.
The head is almost done. All I need to
do is to make the valve guides and lap the valves.
finished cutting the seats.
Boring out the ports.
today was just the normal machine shop stuff. Note in the
left photo the tool I use to cut the seats. This is something
found in a junk pile when I was a kid. It was originally a
operated seat cutter but I turned the shamk to fit one of my collets
and it makes really nice seats in the mill.
You will also
note that, when I bored the ports (right photo above), I mostly guessed
the positions of the ports. The main thing that I worked into
design is that, when the flat on the top bearing plate is vertical, the
angle is correct for the ports. Using the Type A-1 Eyeball
the ports to align with the bores below the valves. Also
it easy is the fact that I have the ports coming out exactly half way
up the head.
Test fit of gears.
may have a problem with the spark plug thread. Somehow, when
worked up the drawing, I didn't get the tap drill size right for the
plug so the threads are shallow. Since there is about 3/4" of
thread on the plugs, it should be all right. If not, I can
go back and make a bushing to press into an oversize bored hole, then
stake it on the inside of the combustion chamber. I'll do
I need to.
I'm going to go ahead and make the brass valve guides
and get the valve keepers made and the valves lapped and in.
Then, all that is left besides the manifolding, is the rocker
arms, the cam followers and the cam.
valve guides and keepers are done and the valves are lapped-in.
may go ahead and make a gasket and bolt the head down to check for
valve leaks. If they are all right; the head can be
permanently mounted (Unless that plug thread fails).
We have valves!
shaft for the cam gear is in place but still must be cut to length and
the end drilled and tapped for the cam follower bracket mounting bolt.
got the head on the engine. The spark plug tightens up all
even with the loose thread fit and the valves seem to be holding
pressure fine, although the seat on the intake is a bit thin.
rights, I should have put the valve in the lathe and used the Dremel to
change the angle of the face until it matched the seat in the head.
It should work fine, though.
You will notice
that I filled the precious valve port in the cam by pressing in a plug.
The plug disappeared (mostly) after finishing the cam.
milling the cam, I spent a lot of time turning the crank on the rotary
table. While doing so, I realized that the geometry of the
profile is more complicated than I first thought. For the cam
ramps to line up properly with the center of the cam, theworkpiece
should have been shifted half the diameter of the cutter on each end of
the cam rise in order to have the ramp square to the center of the cam.
Then, there's the complication of having to compensate for
diameter of the cam follower and the valve lash.
I ended up making it to the design specification and will see how the
duration works out.
sideshaft will need to be replaced, as the length and position of the
components mounted on it have changed. Right now, I have a
piece of shafting just to check clearances.
geasr tooth clearances are just right and they run smoothly.
changed from a bronze thrust under the cam to a PTFE (Teflon) thrust.
I had the material and, since it's self lubricating, I won't
worry about oiling it.
It looks like the cam followers and rocker arm assembly are next.
Spent the whole day on the cam shaft and the cam
followers. There are a lot of fiddly bits to those parts.
We have cam followers!
fits and I think it will work. The only thing I have to
is the overlap. It's about fifteen degrees now.
a racing engine and with that amount of time both valves are open, it
won't want to run slow. I'll pull the cam off and set it back
the rotary table and correct the landing ramps so they are
perpendicular to the centerline of the cam and that will possibley
reduce the overlap to where it will work out. I'd like to see
about five degrees or so..
Tomorrow, once I get that sorted out, I will make the rocker arm
The sideshaft is made and in place.
a sort of slow, klutzy day today. First, when drilling a
hole in the small timing gear for oiling the top bearing, I broke off a
bit. That took about an hour to fix. Then, when
rocker stands, I snapped a 6-32 tap in one of the uprights.
fiddling for about a half hour, trying to save the part, I finally
gave-in, tossed it into the trash and made another one from scratch.
I need to buy some new taps!
In addition, I made a couple of degree tapes for the flywheel so I
could check the valve timing.
Here it is with the rocker stand.
I had hoped to
have the rocker arms done today but, stuff happened.
rudimentary check of the cam timing was done and I found that the
duration is about 220 degrees, much too much considering that is the
duration for both valves. That will make for about 40 degrees
overlap! Kind of radical, I think. I will put the
in the mill and whittle on it to get the duration down to about 190
degrees. That will have the exhaust opening at about 5
before BDC and closing at about 5 degrees after TDC.
the intake will open at about 5 degrees before TDC and close about 5
degrees after BDC. That ought to be fine for a low performance slow
running engine. I can always shift this a bit by changing the
overall valve timing.
When I get the rockers and pushrods done, I can tweak the cam.
close yet so far! The rockers and pushrods are done, the cam
modified for about 190 degrees duration (with valve lash of 0.010"),
the exhaust adapter is done and the mixer adapter nearly done.
suppose I should have bored the ports out to 1" instead of leaving them
at 7/8". I just didn't think about it while the head was in
mill. Anyway, I made some adapters to increase the ports from
7/8" to 1.048" which is what the ports were.in the rotary valve
arrangement. The exhaust is a press fit for both the adapter
the pipe. The intake adapter will be a press fit in the head
a slip fit and setscrew to mount the mixer from the rotary valve
I've also got to move the fuel tank down so the filler clears the mixer.
just may work out that I can hook the governor to the throttle of the
mixer and get it to work. That arrangement will keep my hands
free to make adjustments without having to chase the throttle setting.
for the suspense moment. I have to be out of the shop with a
cardiac monitor until probably Wednesday so the final push and start-up
will be delayed at least until then.
I snuk out into the shop and got the engine ready for a try at
starting. Here's how it looks, ready for the attemptt.
that's left is to turn on the ignition and crank.
All the shrouds are on and the governor is
The governor is
connected to the throttle arm via a length of music wire.
Although the alignment is off and the setup will probably
some revision, it should work after a fashion.
I did crank it
through a couple of intake strokes to make sure the mixer was drawing
fuel and I was tempted to turn on the ignition and see if it
make smoke but, since lunch was ready and
because of the cardiac monitor I'm wearing, I'm not supposed to get
knowing me, I will shed a puddle whilst cranking.
I've made the executive decision to take the rest of the day off.
Tomorrow, if I get back from town in time, I will give it a
fifty) and see if it will cooperate. I will, of course, make
of it, which will ensure that it will not cooperate.
last thing to do before starting the engine is to respond to a numerous
request by the Australian Head Office of Hoyt-Clagwell &
Denis Basson, President of the office, obstreperously threatened
to have a snit fit if I didn't make a finger guard for the top gears.
Asceding to his wishes, here it is.
The gear guard.
completing the ordered task, I rolled the engine out into the driveway
and spent some quality time with it. In the end, it ran but
needs a bit of tweaking. One of the things I did to make it
stronger was to increase the size of the venturi. This
to breathe better and make more power. I did try it with the
venturi completely removed and the engine really took off although it
wouldn't idle at all. Maybe some fiddling with the flutter
would get it to do better with a wide-open mixer throat.
are some things I think I can do to make it run better. One
put an O ring on the mixer body where it goes into the adapter.
notice that it blows a little fuel out of the approximately 0.001"
clearance between it and the adapter. I think this small leak makes the
engine do a lot of 8-cycling. Adjustment of the fuel mixture
flutter choke doesn't fully stop this. Valve overlap could
cause it. In addition, I think the governor is too sensitive.
This is easily remedied by simply moving the music wire from
hole nearest the throttle shaft to one farther away.
thing that may be making it misbehave is the fuel. I'm still
running what is left of the 32:1 two cycle mix and this probably
doesn't make the engine happy.
I've also noticed what may sound
like a leaking head gasket although it could also be a squeak in one of
the casters. With my hearing, it's hard to tell where it's
I've got to get The Mighty Hoyt-Clagwell 54-75
ready for the Zolfo Springs show so I may not be spending much time
with the engine until I return.
got some time yesterday and made some improvements. First of
I cut a groove in the O.D. of the mixer tube into which to put a small
O ring to seal it agaist the I.D. of the adapter. This
the slight air leak that was enough to mess up the idle mixture.
I also set the wire pivot point on the throttle
least sensitive position for the governor. Both of these
helped but the governor is still too "twitchy".
As soon as I get some more time, I will re-design the governor so it is
not as sensitive.
up the fan and fully enclosing the fan in the shroud should
the cooling. In the last run of about a half hour, the engine
temperature looked like it was stabilizing at about 230 degrees but I
won't know for sure how well it will do until I get the governor
settled down so the engine will run steadily.
March 2017: Back
to the project. Spent most of the day working out a new
using the bones of the old one. This one should be a little
sensitive and may allow the engine to run steadily.
The new governor.
kinda obvious I'm a lazy Geezer. I didn't remove any hidden
but you should be able to make out how it works. The total
of vertical movement between slow and fast is about 0.500", a little
more than the movement of the throttle arm on the mixer when set at the
minimum sensitivity setting (the farthest out hole on the arm).
the weights don't stick out as much as before, it will require a spring
with less force. The spring is inserted between the top arm
the governor (that the weights pivot on) and the vertically moving
lower portion (where the links connect from the weights. With
less stickout, there is less chance of getting whacked by a governor
weight. I'll start building it in the next week or so.
7 March 2017 The work today went better than I thought it
would. The new governor is made and installed.
making the new governor, I figured out why the other one was so
sensitive. The farther out from the center of rotation the
weights are, the more centrifugal force is generated. The
of force increases too fast to be manageable. With the swing
weights, the angle they swing to as the engine speeds up changes slower
as the weights move out. In any case, the engine runs better
but there are still some stability issues.
One thing I noticed
is that the engine occasionally "jerks" while it is running.
think this is caused by the wasted spark setup (crankshaft speed timer)
I have on the engine now. With the new valve setup, it will
easier to go to a single spark (cam speed timer). I think
happening is that the wasted spark is somehow causing a disruption in
the timing making the engine fire way early. It could be
something else like some kind of glitch getting into the ignition
module but I really don't think that is it.
It ran for a bit
over a half hour at a little over 700 RPM and the temperature at the
top of the cylinder was about 225F when I stopped the test run.
Anyhoo, here is the latest flick.
Engine running with new
Today, I moved the ignition up to the cam gear
so it is no longer a "wasted spark" ignition system.
New ignition timer.
using a Hall-Effect transistor that senses the little magnet you can
see on the side of the cam. It seems to work better than the
other system, I think, because the magnet is on a longer radius so the
magnet passes the sensor faster, allowing less "jitter".
The mixer got a going-over. I made a new arm on the side
opposite the throttle arm and made an idle stop.
the ignition timing set to 10 degress BTDC, the engine started easily
and ran tolerably well although it but still 8-cycles more
I'd like. Tomorrow, I will fiddle with the flutter choke
Maybe a lighter one will allow the idle mixture to be leaner
while allowing enough fuel for acceleration.
Today, I ran
through a full tank of fuel (naphtha) with only a few short stops for
fiddling. The RPM was mostly in the 650 range. At
of the run, the temperature was getting close to 250F with no signs of
I think that, with improved carburetion, slower
running, a little more cooling fan speed and more shrouding, the engine
temperature will stabilize below 250F.
13 March 2017: Because of the noise, I used most of the day
making a muffler. It works okay, quieting the
Muffler on engine.
made from stuff sitting around. The inner tubes are cut from
length of heavy wall tubing. The outer shell is part of a
deceased satellite dish mount. The size and number of holes
the inlet and outlet pipes was figured to have slightly more combined
area than the exhaust port on the engine. It was a matter of
picking a drill size, figuring the area of the holes it made then
dividing that number into the area of the port. 24 number 15
drill holes was about right so that's what I went with. Once
run it long enough to cook the paint, I will wire-off what is left and
repaint with grill paint.
Oh, yes - in the right-hand photo
above, you can see my variable speed modification just below the
governor. The lever pulls on a spring that takes the place of
concentric spring that used to be on the governor shaft. I
have to pick a prpoer spring because, with what is on there
there isn't a lot of speed change, from about 600 RPM to a little over
Incidentally, the engine seemed to run happiest today
at about 800 RPM. After running another tank of fuel through
the temperature was about 240F.
haven't figured out one problem the engine has developed.
it's warmed-up, it occasionally "jerks" like it's suffering from
detonation. I changed over to pump gasoline from the naphtha,
figuring the higher octane would solve the problem. Not so.
It's the same with either fuel and is independent of ignition
timing setting. It also pops back through the mixer
I hope there's not a hot spot in the combustion area because
will be a P.I.T.A. to pull the head but if I have to, I will.
stripped and painted the muffler. While waiting for the paint
dry and using air, I checked the cam timing. The overlap is
than I thought, only about five degrees, which is fine for this engine.
The timing was about five degrees advanced, with the intake
opening at about 10 degrees BTDC and the exhaust closing at
TDC. I made a small change so the overlap is just about
on TDC. The engine runs better now but still spits back
occasionally. I will retard the cam timing about another five
degrees so the intakc begind to open at TDC and the exhaust closes
about 5 degrees later.
My theory about the spitting back is that
there is lingering heat from combustion when the intake opens and that
fires the charge that is entering the combustion chamber.
keep fiddling but it's now running almost respectably. Here's
March 2017: Over
the last few days, I've been fiddling with the engine. I made
addition to the fan and cylinder shrouding and made a new and larger
diameter drive pulley for the fan. It appears to be cooling
I also pulled the head and checked for burrs and
head gasket fuzz that could have been causing the detonation "jerking"
of the engine. Nothing jumped out at me but I carefully
anything that looked like it had a sharp angle. While I was
it, I re-lapped the valves but they probably didn't need it.
Before putting the head back on, I cut the gasket back so it
doesn't protrude past the inner diameter of the liner to make sure
there were no tiny hot spots.
After putting it all back together
this afternoon, I did a test run. It still spits back and
spells of not wanting to run smoothly. I didn't notice any
"jerks" this time. It ran for over an hour on a tank of
better "economy" than I've seen so far.
With a little over an
hour of continuous running at about 500 RPM with no load, the
temperature at the top of the cylinder stabilized at about 250F so it
may be cooling all right.
Next is to mount one of my
90 Volt permanent magnet DC motors on the skid and belt it to the
engine to see how many light bulbs I can light with it. That
also be an acid test of how well it cools.
29 March 2017: After
a haitus to take care of some buisiness, I got some time in on the
engine. I haven't changed anything with the engine but have
the permanent magnet DC motor. Today, was the first test of
engine under any kind of load. I was running three 150 Watt
and one 40 Watt bulb. The voltage with the lights on was
volts so a wild guess as to the power the engine was producing was
around 3/4 horsepower. The engine wasn't nearly loadedup and
will have to do some adjusting on the governor to get it up to anything
near the full load of 500 Watts.
Chugging aweay making a little power.
At the end of about a half-hour run under load, the
temperature was around 250F, which isn't too bad.
much got done today. Still trying to figure out what the carb
backfires are all about as well as the 8-cycling. Today, I
removed the venturi and sleeved it down to see if that made a
The bushed and re-sized venturi.
re-sizing the venturi, it had been reamed out to 0,406". I
press-in aluminum insert and reamed it out to 0.265". The
started and ran about the same with -maybe- a little improvement.
The power output seems to be only slightly less.
I'll run it like this for a while like this and keep working on the
backfires and 8-cycling.
2 April 2017: Well!
No wonder! I did a really semi-careful valve timing
and here's what I found. The exhaust opened at 158 degrees
Top Dead Center and closed at TDC for a duration of 202 degrees.
The intake opened at 24 degrees Before Top Dead Center and
at 5 degrees Before Bottom Dead Center for a duration of 195 degrees.
Right there, I show my inaccuracy in taking measurements
with the face cam operating both valves, the durations should be the
same. In any case, with an overlap of 24 degrees, it's no
it was spitting back. That amount of duration may work fine
an engine running at 5,000 RPM but not a thumper like this.
fix the overlap problem, I removed the cam and put it in the mill,
removing some of the lobe. When I got it back together it
wasn't right but was closer. With the new cam duration,
what I got. The exhaust opened at 170 degrees BBDC and closed
TDC for a duration of 190 degrees. The intake opened at 10
degrees BTDC and closed at 5 degrees BBDC for a duration of 185
degrees. The overlap was 10 degrees. My method of
the timing was to carefully set the lash at 0.010" then, using degree
strips on the flywheel, I turned the engine until an 0.002 feeler gauge
became tight under the valve stem. This probably 'splains why
there are differing durations for the intake and exhaust valves.
test run showed some improvement with less 8 cycling but there
still the occasional carb backfire so I suspect the overlap is still a
bit much. I loosened the lash for the intake valve (made no
timing measurements) and it ran a little better. Tomorrow, I
again take the cam off and whittle some more off of the lobe, trying
tor either zero or a couple of degrees of overlap. This time, I will
use a dial indicator on the valves to determine when they begin to
open. I can't get any more accurate than that.
for the carb backfires is that the intake valve opens while the hot
exhaust stream is still flowing and a little flows back into the
intake, igniting the mixture. It's only a theory but it makes
sense to me. the 8 cycling is most likely due to exhaust
of the mixture. Adjusting the mixture and flutter choke do
April 2017: The cam timing is now as follows:
Checked with 0.010" lash and using dial indicator on spring retainer to
Open - 178 ATDC
Close - 2 BTDC
Open - 2 BTDC
Close - 178 ATDC
gives both valves having a duration of 180 degrees and zero
overlap. The 2 degree figure is due to that being as close as
could get it with a setscrew on the sideshaft.
I ran the engine
and it now doesn't 8-cycle if I hold the throttle in position.
low speeds, it 8-cycles due to the governor responding to engine firing
impulses. Retarding the spark eliminates this but for running
slow, the spark needs to be about 25 degrees ATDC, which makes the
engine run hot. After a fairly long run, the temperature was
close to 280F. I don't consider this to be excessive but
stop if it reached 300 degrees.
As for the spitting back and jerking, it still does it occasionally so
now, I think I need to work on carburetion.
the last few days, I've modified the design (Version 4) and built a
couple of my "Cheap Ignition Circuits". This one has an LED
ignition module is the white box below the fuel tank.
coil is one for a Toyota
been searching for cheap non-high energy ignition coils and am
experimenting with a "dry" (non-oil filled) coil that is a replacvement
for Toyota and Suzuki (among others). They come with a
and a ballast resistor. I dispense with the ballasts and
the half of the bracket that holds it. You can see the coil
mounted below the fuel tank with the ignition module. So far,
is working well.
I'm still using a magnet on the cam for timing
but am now trying a magnetic reed switch that is mounted inside a piece
of copper tubing. So far, it is working well. I
the revised schematic and details of the sensor on my "Cheap Ignition
After some thinking and a bit of fiddling, I may
have come up with one of the reasons for the engine spitting back and
jerking. After the plug fouled this morning, I decided after
cleaning it, to open up the gap from 0.025" to 0.032". It
to run better with less spitting and bucking. This afternoon,
will enlarge the gap to 0.040 and see if it is better yet.
6 May 2017:
been a while. First, the increase of the plug gap to 0.040
improve things so, today, I tried something else. I had made
10mm standard reach to 14mm standard reach adaptor a while back so I
took a long reach 14mm plug I found on the roadside and made a sleeve
so it would fit in the adaptor. Since the head is threaded
long reach 10mm plug, I figured the combustion chamber volume gained
from the "unused" 10mm thread plus the volume of the adaptor plus the
volume of the larger spark plug would lower the compression ratio
enough to be able to see if lower compression would stop some or all
the foolishness of spitting and bucking.
Spark plugs and adaptors.
Spark plugs after
45 minute runs.
Spark plug on
adaptor on engine.
the left-hand photo at the top is the long-reach 10mm plug I've been
using. In the vertical center to the left is the adaptor, in
middle is the sleeve to have the 14mm long-reach "road find" plug fit
into the adaptor and to the right is the long reach 14mm plug.
People have been saying that lash-ups like this cannot work
well to ignite the charge because the charge has to flow up through the
hole in the adaptor to the plug to fire. In operation, it
to work fine and the engine runs steadily. I also tried a
standard reach "junkpile" 14mm plug as shown on the bottom of the
left-hand photo and the engine didn't seem to like it quite as much,
probably due to the smaller volume of the smaller plug.
center photo shows the original 10mm plug and the "new" 14mm plug
side-by-side after running about 45 minutes. You can actually
a little color on the 14mm plug while the 10mm plug is oily.
the photo on the right, you can see the larger plug on the engine.
engine was started and it seems that it can stand a bit more spark
advance, doesn't spit when warmed-up and hasn't bucked once, even after
the engine temperature stabilized at 260F while running at between 500
and 600 RPM. Actually, the engine is stabilizing at a
lower temperature most likely due to being able to run the timing a bit
If, after thinking about it for a while, I decide
that the compression should be lowered a bit more (and permanently), a
thicker head gasket or the plug hole can be bored out and threaded for
a standard reach 14mm plug. Either way, the added volume may
7 May 2017: I've done a bit more spark plug/compression
ratio experimentation. Today, a longer 10mm/14mm adaptor was
adaptor made using threads from 10mm plug.
Plug with adaptor on engine.
The new adaptor
was made using the threaded portion of one of the 10mm long reach
plugs. The 14mm female thread in the adaptor was made the
way using a 14mm thread chaser which wasn't designed for threading.
It took a while and a bit of elbow grease but it
good threads. The adaptor has a little more volume than the
one and allows more thread engagement in the head and full engagement
for the plug.
The engine started readily and ran pretty well
but, not being satisfied, I stopped it and removed the 14mm plug and
used the sleeve that I made yesterday to give more volume in the
adaptor. This time, the engine didn't run as well.
the problem is that I finally got enough volume between the plug and
the combustion chamber to make the charge at the plug iffy.
engine would accelerate fine but when it was allowed to idle, it
8-cycled no matter how the fuel mixture was set. I think
with the denser charge on acceleration, enough mixture got to the plug
so it could ignite it more reliably but was too rarified at low
throttle settings. I went back to the new adaptor and the
ran a lot better.
Then, while I was sitting "supervision", it
began to occasionally run rough, hunting and misfiring. It
eventually correct itself. The engine skid was sitting on
concrete and I could see it teetering a little. The teetering
worse when the engine started acting up so, on a whim, I put my foot on
the skid to hold it steady. The engine straightened out and
right. I figured (correctly) that the problem was a bouncing
The check valve was removed and the 0.130" ball was
replaced with a 0.200" ball (the biggest that would fit in the
housing). After that, everything was hunky-dory. I
the gas tank and ran it dry, having to occasionally open the needle
valve as the fuel level fell. Just before it ran out of gas,
temperature was just barely 250F
I tweaked on it until it would
run well at 400 RPM if I kept an eye on it. If I revved it up
around 1,000 RPM and advanced the timing, it ran really well but I
don't want to run it that fast. I set the speed to between
and 500 RPM for the run,
I've got to see what the ignition
timing is when it's running around 500 RPM. I think it is
after TDC for best running.
8 May 2017: Today,
I made a new needle valve assembly. The needle has an 8
taper and seats against a #65 (0.035") jet. This gives a much
When tested on the engine, it worked a
lot better than the larger one and the engine is nearly ready for prime
time. After running a full tank of gasoline through it at
400 and 500 RPM with the timing retarded so it ran well, the
temperature was just a slight amount above 250F. I think if I
get a handle on the timing issue and get it running with spark advanced
a few degrees, it should run substantially cooler.
400 RPM, in order to keep it from 8-cycling, I have to run the spark
timing retarded 30 degrees after top dead center. I don't
where this oddball timing is coming from. Too little flywheel
mass? To high compression? Even at 700 RPM the
running about ten degrees retarded. This is a mystery to me.
Anyone got answers?
2 June 2017: Over
the last while, I've experimented with lowering the compression by
removing the head and installing an additional 0.0625" thick head
gasket. All that work and there was no improvement so I took
apart and removed the extra gasket.
I'm now trying for a
hit-and-miss camstopper arrangement. This brainstorm is going
take some refinement to work well. As it is, the engine runs
the cam doesn't stop at a predictable position so erratic running
Installed on the engine.
at the left-hand photo above I think you can figure out how the
arrangement works. Note that the sideshaft gear is now
to float on the sideshaft. A pin is bottomed-out in the
hole threads and acts as the latch pawl.
The aluminum sleeve is
new. It slides vertically on the governor shaft, rotationally
locked to the shaft via the setscrew/pin on the right. In
to slow wear on the aluminum from the latch pawl on the gear, I have
pressed a small dowel pin axially into the sleeve for the pawl to bang
There are two drillpoints on the governor shaft
that, with the ball bearing, act as a toggling mechanism. The
spacer and flat spring hold pressure on the ball so the sleeve wants to
settle into either of the drillpoints. In the right-hand
you can see how the sleeve is operated by the non-rotating part of the
governor that is attached to the weights. A spring is used to
the speed at which the governor unlatches.
the timing gear engaged.
at the photos above, on the left, you can see how the gear is engaged
through the sideshaft (timed with the setscrew/sleeve guide).
This locks the sideshaft to the governor shaft and
to the sleeve. Below latching speed, the sleeve is in the
position, engaging the notch with the latch pawl,
gear to the sideshaft. On the right, the gear pawl is
with the sleeve.
I think that, so far, it is workable but I do
need to find some way to make the sideshaft gear disengage at the same
location (exhaust valve open) every time it is latched out.
18 June 2017: After
a thinkin' pause, I've finally come up with something that may work to
stop the cam while the exhaust valve is open. It is
by the fact that the disengagement/engagement of the sideshaft gear is
at crankshaft speed. This scheme has the latching controlled
cam position. To make this happen, I have had to machine a
cam on the reverse side of the intake/exhaust cam. There will
a roller follower at the cam, a rocker arm, rocker arm pivot and a
pushrod to disengage the gear when the exhaust valve opens.
least, that's what is supposed
The cam gear was positioned on the rotary table and a partial groove
Rotary filed lead-in and
will be able to see how this Rube Goldberg is supposed to work as I
make more parts and assemble them. If the hit and miss
arrangement works smoothly, I may be able to dispense with the ugly
cooling shrouds. I will leave the fan, in any case.
21 June 2017: Things
are going kind of slow here at Hoyt-Clagwell & Company.
more parts are made for the hit and miss configuration.
cam follower, rocker and rocker stand.
open (latched or
I'll try to 'splain how this part of it
works. In the photo on the left, the cam follower is the
cylindrical part on the right. It has a small ball bearing
runs in the cam on the underside of the gear/valve cam. It
against one end of the rocker arm. The other end of the
arm pushes a rod up when the exhaust valve is open.
will, through a toggling arrangement (still to be thought-out) that
pushes a pin at a right angle into the bore that the push rod runs in.
When the rod is blocked, it will force the clutch sleeve up
disengage the gear the next time the exhaust valve opens.
to be done is a guide, a riser block, the toggle and a new
for the crank speed timing gear. I think this whole thing
make sense once I have it more or less finished. Even better
be if it actually works and I can make a slow motion video showing it
doing it's thing.
The whole thing will, in theory, work but
there may be issues with the cam gear not stopping soon enough to hold
the exhaust valve up. If that is the case, I can make a drag
clutch on the cam gear that will add just enough friction to ensure it
stops at the right time.
23 June 2017: Today, some more parts got made.
This was time consuming because of the accuracy required to
make the fit really close.
Here's the slider and post.
governor pushrod goes through the hole in the slider that is inline
with the post. The hole in the side is for the latch pin.
still have to make the slider cover and drill and tap some holes.
At that point, I will be making the shift collar.
decided to make a whole new collar out of some air hardening steel a
friend gave to me. It will look something like the aluminum
that was on the former iteration but, since I will be hardening it, the
latch pin won't wear it.
Now, I'm sure you're confused as to how
this lash-up is going to work but, once it's done, I'm sure it's
operation will be semi obvious.
24 June 2017:
took all day but I now have the slider and post done. It took
some doing to get the pushrod to line-up so the slider worked smoothly.
A bit of fiddling and it's working.
Post, slider and pushrod in position. Collar will be replaced.
6-32 screw hanging out of the slider cover is for a spring to pull the
works down when the governor trips the toggle that forces the pushrod
stop pin out of the way so the collar can move down to engage the
sideshaft gear. When the engine is not latched out, the
pushrod just moves up and down in the slider bore.
To make sure
the collar design is all right, I used the old aluminum one to test for
fit. Now, to the CAD to design the collar.
25 June 2017:
Today was spent making a little piece out of a big piece.
out with the Mystery Metal.
Turning down the O.D.
off the O.D.
Boring the I.D.
Honing the I.D.
Semi finished sleeve with mating
only reason for all the photos is to show you what took a full day with
my little lathe. Over the years I've owned it, I have mapped
maximums it can take without choking or breaking a belt. As
was, I was taking 0.010" (radius) cuts all day. It's a wonder
didn't fall asleep standing there.
What's left is to mill the
slot for the drive pin from the governor shaft and mill the engagement
slot in the bottom face and hand whittle a lead-in ramp for engaging
26 June 2017: The latch sleeve is done and working.
pin out, gear engaged.
Blocking pin in, gear
Anothre view, gear engaged.
Another view, gear disengaged.
What happens is that the
governor controls the blocking pin on the vertical slider.
slider has a ball bearing that runs in the slot in the sleeve so when
the slider rises, so does the sleeve. When, below governed
the blocking pin is out as shown in the above left photo and the
governor pushrod just slides up and down in the bore of the slider and
the slider remains down.
When the engine speed increases,
the governor operates a toggle that snaps the blocking pin into the
path of the governor pushrod. This allows the governor
raise the slider and sleeve and disengage the drive pin on the gear
when the exhaust opens. Remember that the small timing gear
floats on the sideshaft, only driven by the governor shaft through the
slider and sleeve. (not shown above is the drive slot in the
I still have some tweaks to do on this part of the
mechanism. I have to modify the rise slope of the governor
because it takes a little more force to get the sleeve moving out of
engagement than I'm happy with.
Right now, the
disengagement cam has the sleeve disengaging the drive pin before the
exhaust valve is fully open and before the disengagement cam is at the
top of it's ramp. As you can see in the bottom right photo
is only a few thousandths of an inch of clearance between the top of
the drive pin and the sleeve. If the cam is turned a little
the clearance increases to about 0.050". Modifying the
cam ramp for easier rasing of the sleeve will retard the timing of
disengagement a bit and allow a little more clearance.
the above conditions occur at cranking speed. I think the
will go away at running speed. In fact, it might go to the
direction in that the inertia of the cam gear will keep it moving until
the intake valve opens and that will make the mixer unhappy.
29 June 2017: The toggle is done and on the slider block.
Here are the parts for the toggle with their marked-up drawing. Shown
in the latched position.
Shown in the unlatched
In the left-hand photo, the engine is at
governed speed and the governor has pulled the horizontal toggle lever
up. This is the latched-out condition You will see that the
short vertical test stub that simulates the governor pushrod is blocked
from rising above the latch pin on the left. The toggle has the
latch moved to the right, blocking the pushrod from moving up, causing
the block to rise with it, taking the sleeve with it and disengaging
the sideshaft timing gear.
On the right, the engine has slowed
and the governor has pushed the toggle lever down, which pulls the
latch out of the way of the pushrod (seen up in the block). This
causes the block to fall, taking the sleeve with it and causing the
slot in the sleeve to engage the pin in the sideshaft timing gear.
Clear as mud, you say? Soon, I will see if this bit of mental wandering will work.
30 June 2017: Well, I thought that today would be the day that I would first run the engine but Mister Murphy had his say.
A slight bearing failure.
turning the engine slowly and after having tripped the toggle, the
governor cam started lifting the slider and collar to disconnect the
sideshaft timing gear. Unfortunately, the governor cam follower
couldn't stand the strain of also lifting the governor weights.
On the left, above, you can see the result of this AWSHOOT!
rooted through my small ball bearings and found one that was a bit
larger. It took some modification of the follower plus a sleeve
to reduce the bore to 1/8" for the pin. Then, since the diameter
of the new bearing was larger than the original, I had to deepen the
slot in the bottom end of the follower that the rocker runs in.
All of this took almost the whole day.
The governor latched.
did get it back together and the governor works after a fashion.
It looks like I will need to modify the governor itself to give
more movement. The way the setup works requires the governor to
provide substantially more motion than the slider. Otherwise, it
will either not latch out or unlatch or it will cycle between them.
Tomorrow is another day.
8 July 2017: It's
been a while and I've been making parts as time allows. After
trying several iterations of the previous mechanical toggle design, I
quit on it. Chasing the slider with the governor just didn't cut
The other day, I decided that what it needed to work right
was a solenoid operated latch so I designed one. This replaced
the toggle arrangement.
solenoid and adapter for the latch slider.
The drag clutch for the cam
I found a
solenoid from a defective irrigation system valve that would work.
It is designed for 24 Volt AC operation but I found that it works
on the existing 12 Volt DC system pretty well. In order to give
it some added oomph to pull the latch pin off of the governor pushrod,
I had to design a circuit that, using a relay and an electrolytic
capacitor put an initial 24 Volts DC on the solenoid by discharging the
electrolytic capacitor in series with the 12 Volt supply. Initially, this worked really well. The relay is energized by a microswitch which worked off of the governor.
The solenoid arangement.
The drag clutch
underneath the cam follower stand.
The engine was tested
by motoring it with the spark plug removed. When it looked like
it was going to work, I put the plug back in, hooked-up the fuel line
and motored it off. It readily began running and, for a minute or
two, it was running properly, with the cam stopping when the exhaust
valve was open. After a while, though, it started running poorly
before it stopped altogether. I found that the setscrew that
locks the governor to the sideshaft had worked loose. I tightened
the heck out of it and resumed testing.
It quit governing and I found that the top crossbar that drives the weights had worked loose so I tightened it.
next run was, again, about a couple of minutes before the governor to
sideshaft setscrew had worked loose again. This time, when it
quit, it was far enough out of time that it backfired and turned in
reverse a couple of turns.
If you noticed that the microswitch
doesn't have an arm on it, you are right. The photos above were
taken after testing. A backfire caused the microswitch arm to be
snagged and it spun off into another dimension because I can't find it.
Anyway, there are some really major problems with this design.
conclusion is that I failed to consider the mass of the timing gears
and the torque required to operate the cams. When the governor
unlatches and the sleeve drops down to engage the pin on the sideshaft
gear, there must be a really big mechanical shock. I think this
shock is worse due to the speed of the engine. If it would run at
a couple hundred RPM, maybe this system would work but, at 500-600 RPM,
the shock of starting the timing gears is too much and bad things
For now, it will sit and rest for a while until I figure
out what to do. Maybe the only hit and miss alternative is to
simply latch the exhaust valve open, letting the cam gears continue to
turn. This may not work for two reasons. The first is that,
if the exhaust rocker is held with the valve open, the little pushrod
will fall out. A small spring could work to keep the follower
connected to the rocker, though. Second, there's the problem of
the intake valve still working and that may be the killer.
only other alternative is to just fully close the throttle past
governor speed. That might be a possibility but the engine would
still be going over compression.
If all else fails, I could just
revert to throttle governing and try to address the cooling issue.
I guess if it was easy, everybody would be doing it.
14 July 2017: I'm
finally getting back to my fiddlings. I suppose if I were keeping
track of the modifications made to the engine, I'd probably be at The
Non-Rotary Valve Engine, Revision 14C(K)128.
decided to try a solenoid latch on the exhaust valve and to keep it
from suckling fuel while it is latched, I will also have another
solenoid close the throttle. I've never seen anything like this
but it should work.
Unlatched, solenoid energized.
Latched, solenoid not energized.
will set it up so the boost relay is pulled-in when the engine is below
governed speed. This will energize the throttle and exhaust
solenoids. In order to make it easier for the exhaust latch
solenoid to work, I will set it up so, after the governor orders a
latch, the relay will wait until the exhaust valve is open. I'll
probably go ahead and use the underneath cam to drive a switch that
will complete the relay circuit at the proper time. When the
governor orders unlatching, power to the relay will be interrupted
causing the relay to drop out and de-energize both solenoids.
Says here in the fine print that it will work. We'll see.
15 July 2017: I
thought I was going to get enough done that I could test with the
motor. Not so! Murphy struck again. This time, the
relay I used to boost the solenoid pull-in voltage decided that one of
it's contacts was on vacation. I spent a lot of time finding that
problem. Usually, something simple like a relay is pretty trouble
mount was made of some 3/8" aluminum plate. It is split where it
slips over the mixer body and is clamped with a caspscrew.
Another of the irrigation system valve solenoids was used for the
throttle control, held in place with the setscrew as shown. A
length of music wire serves well for the link between the solenoid
plunger and the throttle lever.
I'm going to see if the engine
will run all right without the flutter choke or a manual choke. A
finger in the air inlet will serve well as a starting choke.
There is a venturi ahead of the jet so, with the throttle wide
open, there should be sufficient air velocity to draw fuel. We'll
16 July 2017: Well,
Murphy showed-up again. I got everything except the governor
switch mounted up and wired and when I went to test it, after only a
couple of latch/unlatch cycles, the exhaust latch solenoid quit.
The coil had opened-up! DAGNABBIT! Since I didn't have another one like it, I figured, what the heck, I'll see if I can fix it.
If you squint, you may ge able to see the tiny wires I had to splice.
I took the wrapping off of the coil andverrrrrrrry
carefully lifted the little connection board off of the coil.
Sure enough, one of the coil wires had broken off of the chintzy
The whole solenoid is only about an
inch long. A few decades ago, I would have had no trouble doing
this kind of work. I repaired d'Arsonval metters and all kinds of
small stuff and was mostly successful. Ever since I was a little
kid, I was nearsighted and could really see well up close by simply
taking my glasses off. My eyes have gotten old along with me.
Now, especially after cataract surgery, my close vision isn't
worth a hoot.
I have a couple of jewlers loupes but, of course,
the only one I could find was the strongest one. With a lot of
squinting and straining with my face right in the solenoid, I found the
hair-thin wires and used acetone to strip the enamel off of the ends.
Then, fun and games time. I tinned the coil wires and
soldered hookup wires to them. After verrrrrrrrry
carefully checking the leads to make sure I had continuity, I made a
masking tape dam and applied a quantity of E6000 glue* to pot them in
place. Tomorrow after the glue has set-up, I'll again check
continuity then remove the masking tape dam and apply a couple of wire
ties to hold everything in place.
If this fails, I can grab
another of the irrigation system solenoids and use it for the valve
latch but it will be overkill, force-wise.
E6000 glue is about the greatest thing since sliced bread.
It's clear and thick but flows well and dries to a rubber
consistency. It has enough body that for sticking small things
together, the glue will hold things in place until it dries.
Murphy didn't come around so I got some progress made. The
solenoid repair held through the glue drying, masking taping and wire
tying and it all worked.
it is, running in the shop.
The Rube Goldberg electrics.
shot a video of it and uploaded it to YouTube and in doing so, I ran it
for over an hour. Without doing any serious tweaking, it runs
very well. The good news is that the maximum temperature I
recorded at the top of the cylinder was about 150F (65C). It was
running around 450 RPM at the time. Started easily. I'm a
18 July 2017: Today,
a little more testing was done after I removed the 90 volt DC motor and
substituted the alternator and belt that I used on the original 2009
Algore Edition Green Hybrid Hoyt-Clagwell. I had made a regulator
for it that had a constant 13.8 volt output and variable current
limiting. It's a pretty rudimentary regulator and I will have to
use a push-button to manually start it so when the engine stops with
the ignition on, there isn't a constant load on the battery in addition
to the solenoid load..
Working-out with a "light" load.
found that I could load the engine pretty well and it still "8-cycled"
on the governor just before it fell on it's face. That must be a
characteristic of the governor and I may try de-sensitizing it by
shortening the microswitch lever.
I guess I ran it under
varrying loads for somewhat more than an hour and the temperature
peaked at about 215F (102C) and slowly fell when the load was removed.
I'm going to add a diode to charge the battery off of the
alternator so it will at least do a little something.
test run will include volts/amps under load for a really, really rough
idea of what it is doing. An automotive alternator, especially
one that's a few years old is an inefficient thing indeed, so any
numbers will only be relative. With the variable current
limiting, I can load it until it hits a brick wall or lessen the load
to let it recover.
22 July 2017: Over
the last couple of days, I've neatened-up the alternator setup and
added a guard over the alternator fan. Today, I blocked the
throttle control so the throttle stays wide open all the time.
The engine may run a little better that way and seems to be able
to handle a larger load. Fuel usage doesn't appear to be any more
than usual. Tomorrow, I think I'll remove the throttle control
and make a bracket to keep the throttle wide open (probably a piece of
I think today was the first time I've run it continuously
for a whole tank of gasoline. It did well, temperature at the end
of the run was the same as yesterday, running the one light bulb load
plus giving the battery a little charge.
Also, the ignition
timing can now be run as far advanced as 15 degrees or so. This
may be due to running at full throttle in the hit and miss mode.
As expected, with this timing that advanced, if it isn't whipped over
compression "smartly", it will say "oh, no you don't!" but it does run
well and hits hard. FYI, I am running non-contaminated (alky
free) 86 octane marine gasoline. I don't think it would like
naphtha very well unless I retarded the ignition to TDC or later.
There are still a few minor tweaks to do but I think it is essentially finished.
Now, what's next? Maybe a hydraulically injected true Diesel with a 1" X 2" bore and stroke............. Maybe.
24 July 2017: Just
fiddling around today. Made a new mixer body without a throttle
butterfly. Removed the throttle solenoid and wiring. Gave
it a test run.
New mixer and alternator fan guard.
Here are the "excess" parts.
you can see, there were a few parts made that didn't work out. I
think this one has used-up more metal than any other engine I've built.
It does run nice now.
Today, it ran for a little over 45
minutes on a tank of fuel. The load varied with most of it at
about 25 Watts (14 Volts @ 2.5 Amps), with periods of up to a minute at
about 150 Watts (14 Volts @ 10.7 Amps). At about 550 RPM
(average), the engine is about maxed-out at 150 Watts. Today, the
maximum temperature throughout the run was around 215F at full load and
about 200F at partial load. It stabilized after about ten minutes
of running, so I'm pleased with that aspect.
I did note that,
although the engine was running well, it would constantly spray a tiny
volume of fuel droplets back out of the air inlet. I think this
is because of a little "blowing" when the exhaust valve was
latched-out. It doesn't appear to be any kind of a problem but I
will shift the cam timing a little to see if I can minimize it.
26 July 2017: Yesterday,
I ran the engine outside through a whole tank of gasoline. It ran
for about an hour at minimum load of 25 Watts. I found my
revolution counter so I could get a good average of the RPM (it varies
a lot between hits and misses). It was running at about 625 RPM.
The temperature at the end of the test was about 215F. This
was all without the muffler and, it is LOUD!
it was time to figure out what the gas tank held, I did the
measurements and came up with the following. Choose whichever
floats your boat. 18.4 cubic inches, 0.079 gallon, 0.64 pint,
10.21 ounces, 0.302 liter, 301.87 milliliters. It isn't as
thirsty as I first thought.
This morning, before another run, I
checked the valve timing and the intake opens at TDC, exhaust closes at
about 5 degrees ATDC. Cam timing was left alone. The
ignition timing as of the end of yesterday's run and it was 28 degrees
BTDC. No wonder it backfires if I don't whip it over smartly
I pushed it outside again and, this time ran a tank of
fuel through it with the muffler. The fuel mixture and timing
were left alone. It seemed to handle the load just as well as
without the muffler but only ran about 50 minutes on the tank of fuel.
Temperature, after stabilizing, was about 210F. I checked
the RPM during the run and it was at 770 RPM. The speed
adjustment must have gotten bumped up while I was moning it in and out
of the shop. The engine seemed to be happy at that speed.
tank was re-filled and the engine was run again. I adjusted the
governor for 560 RPM and it could barely handle the full load.
When I sped it back to 585 RPM, it handled the load well.
It looks like it's going to be a 600 RPM engine.