9 December 2014: Recently,
I was given an inline two cylinder air compressor. There was
nothing wrong with it except that it was too small for the intended
use. It was several years old but in apparent good condition
although a bit on the grungy side.
The Speedaire Model 2Z499 compressor as received.
it was two cylinder, I assumed that it was two stage, having a larger
first stage cylinder and a smaller second stage cylinder. I
correctly assumed the crankshaft was a 180 degree type with the pistons
arriving at TDC 180 degrees from each other. My first thought was
to make it into a double expansion gasoline engine, using the small
cylinder for the primary 4-cycle engine and the larger cylinder for the
expansion cylinder. The plan was to exhaust the first cylinder
into the second cylinder to further expand and cool the gases before
exhausting them out of the engine.
Yesterday, I tore it down and
found that both cylinders are of the same displacement. In that
case, I don't think a double expansion design will work well.
angle of the photo makes it appear that the cylinders are of different
diameters but the bore (2.750") and stroke (2.000") for both cylinders
is actually the same. Doing the arithmetic gives a displacement
total of 23.75 cubic inches. The crankshaft runs in needle
bearings and the rod bearings are the aluminum rods. The
compressor, at first glance, appeared to be in very good condition with
no wear showing on the bores, pistons or rings.
scrutiny, I noticed that one of the rod bolts was missing. When I
took the other bolt out, it was only slightly snug. Here's what I
top half of the bolt was in the bottom of the crankcase. It looks
like it was overtorqued and stretched when the engine was assembled and
must have broken just before the compressor was taken out of service.
If it had run much longer, it would have wrecked itself. As
it is, I found another 1/4-20 bolt, chased the undamaged threads in the
rod and it's fine now. The bearings are in excellent condition,
even on the rod with the broken bolt.
The crankshaft looks to be
beefy enough to make a decent engine but I only have the use of the
shaft at one end. The rods look a little spindly to me but since
I plan to make a low compression non-screamer of it, they should be
This is where I am at this point. After
cleaning the parts, thinking on it and taking dimensions; I'll start on
the CAD drawings. At this point, I think it will be a
hit-and-miss design to alleviate some of the cooling problems.
I'll have to cogitate on it and do some sketching to come-up with
governor, latching and rocker arm configuration. It would look
nice with side operated valves and walking beams but how to do the
latching with this arrangement will take a little imagination.
decided to make the compression ratio 6:1, so that makes the head space
for the power cylinder 0.333". The expansion cylinder has no head
space except for around the exhaust valve, which is also 0.333 ".
transfer port is drawn but I'm still trying to sort out how to do it
with a minimum of complication.. If I mill a slot from the top I
could make a cap to cover the milled slot down to the top of the
passageway. I'll let it simmer for a day or two before I decide
what to do.
It looks like no matter what I do to make a double
expansion engine, if it's an utter failure, I'll probably have to scrap
the head and make a completely new one for a two cylinder standard
16 December 2014: While
taking measurements, I looked closely at the crankshaft main journals.
The crank is stamped that it is made of malleable iron but they
must have chilled it because the journals are very hard. They run
in needle bearings and I think that the drive belt was too tight (or
something) because the mains are brinneled.
Damaged main journal.
Since the stresses will be higher as an engine, I made the decision to do a fix. It should work.
Semi-repaired main journal.
the journals still mic'd within a half-thousandth of 0.750" all over, I
made steel sleeves and pressed them on the shaft. The new journal
diameter will now be 0.875" when I've finish turned them and I've
ordered bronze bushings with an I.D. of 0.875" and an O.D. of 1.000"
(the original bearing bore diameters).
Because the thrust
of the crankshaft was cast iron against cast iron and wearing nastily,
I ordered a couple of bronze 0.062" thick thrust washers. When
the bearings get in, I will assemble the crank into the block without a
gasket and no thrust washers and use an indicator to find the end
clearance. I will then face an equal amount off of each end of
the crankshaft to have zero clearance with the washers in place.
When I reassemble it with the gasket, it will have the gasket
thickness of end play. Not real scientific but it should work.
17 December 2014: To
get the rear or non-pulley end main bearing out, I either had to make
some sort of a hook tool to pull it out or resort to stern measures.
Since the other needle bearing was in pretty tight and I had to
use the press to get it out, I decided to make a "Maintenance Port" in
the back of the block.
the "Maintenance Port"
The "Maintenance Port" "Maintenance Port" with cover in place.
that the back end of the "rear" main bearing is accessible, it was
simple to press the needle bearing out of the block. The bushings
and thrust washers should be here tomorrow (this evening if I'm lucky)
so I can finish the mains, paint the compressor and partially
18 December 2014: McMaster-Carr
came through again. The bushings and other parts were delivered
just over 24 hours from the time I ordered them!
Anyway, today I
got the main bearings fitted and assembled. While still thinking
about how to do the head, I did some painting.
Ain't it purdy?
it's impossible for me to throw anything away, I used some of my old
automotive enamel. The red is left over from when I had the '50 Chevy.
Not my favorite shade of red but it works here. The
cylinder block is painted with paint left over from the Model T Coil
Tester restoration. The flywheel is left over touch-up paint for
a motorhome we had several years ago.
I'm not sure how well the cylinder block paint will hold uo because of the heat. I can always repaint later.
22 December 2014: As
usual, I've had to take the crankshasft out again due to a change of
plans. When I started-in drawing the camshaft drive and valve
actuation, I discovered that taking the cam drive off of the front
using a chain just wouldn't do so I rooted in my box of goodies and
found a pair of 1:1 miter gears and another pair of 1:2 gears.
Excellent! A vertical sideshaft is in order.
only problem with that idea is thast I had to take the drive off of the
rear of the crankshaft and that presented a problem because the tail
end of the crankshaft is short. The only thing to do was to
remove the crankshaft and extend it a bit so the driving gear
could be fitted.
Drill and tap the crankshaft
Add the extension using
1/4-20 all thread and Loktite.
took a chance that I could drill through the chill hardness at the end
of the crankshaft. After facing it using carbide, it drilled and
tapped just fine. I made the extension out of some 0.750" Leadloy
steel. It was drilled and tapped for the 1/4-20 stud and, before
screwing the two together, they were both cleaned then assembled using
bearing set Loktite.After tightening the extension, the steady rest was removed and
the back end of the crankshaft was carefully centered, then center
drilled. The center was used to turn the extension to fit the 0.625" bearing I.D and the oil seal.
then milled a flat on the extension for a set screw. The gears
had holes drilled but were not threaded. When I went to
drill them for the 1/4-28 setscrews, I found that they were HARD.
Now, the plan is to use 10-32 screws which are a snug clearance
in the spring pin holes. The shafts will be drilled and tapped
slightly off-center and the screws will make the gears a slop-free fit.
The reason I'm not using spring pins is that the gears must be able to be removed. Spring pins make that a chore.
26 December 2014: Before
Christmas, I got the cam blanks done. Then Santas brought me a
nice 2" thick by 5" wide by 12" long piece of cast iron. Am I a
lucky guy or what?
Raw material for the head.
be doing more CAD work and will post the new drawings as soon as I get
far enough along. I've abandoned the camstopper for two reasons.
First is that there isn't enough space to do it right and,
second, it would only stop a small portion of the camshaft. Right
now, I'm working out the governor and latching linkage.
27 December 2014: The lower gear bracket and seal mounnt are made.
The side view drawing so far.
is a 1:1 gear pair at the crankshaft and, above it, on the camshaft, is
a 2:1 pair. I think I'll drive the ignition timer from the
flywheel end of the camshaft.
Although I will probably change
the style of the governor in order to use brass balls, the drawing
shows my latest ideas for the governor latch The governor pulls
up the rod as the engine speeds. This, in turn and through the
bellcrank, causes the latch rod to move to the left. The latch
rod catches a hardened pin on the cam follower to hold the power
cylinder exhaust valve open. I'm going to let the expansion
cylinder exhaust valve continue to run when the power cylinder is
latched out. There will be no power loss from doing this.
cam followers pivot on the end opposite that shown. Valve lash is
set by inserting or removing shims in small cups that fit over the ends
of the valve stems. The power cylinder intake valve is
Gear bracket in place and the head that needs just a teensy bit of machining to be finished.
you can see in the photos above, I'm using the 10-32 cap screws to hold
the gears to the shaft. In order to make sure the gears are tight
on the shafts, I've drilled and tapped the shafts a few thousandths
off-center so the screws will interfere with the bores in the gears.
29 December 2014:. After
working with the CAD for a day, I just had to make something.
Today, it was the valves. Well.......... I got
started on them, anyway. Since I am going to pein the valve stems
where they go through the valve heads, I needed to get around to
finally making a set of copper jaws for my big vise. The making
of these caused everything to come to a screeching halt.
Tomorrow, I should finish the vise jaws and get back to the
Here's what I've done today.
the cast iron valve heads.
Parting off the heads.
found a cylindrical piece of cast iron that was the core of a hole that
I hole sawed out of a flywheel. It was just big enough in
diameter to turn clean at the dimension I needed. Then, it was
drilled for tapping 1/4-20. Before parting them off, each
head got threaded with four turns using a plug tap. The plan was
to bottom out the valve stems in the threads of the heads.
Two of the valves semi-finished.
parting off the heads, the stems were made with 0.246" diameter drill
rod. The head ends were threaded 1/4-20 for four turns. The
heads were screwed on using bearing set Loktite (which will probably
disappear once the engine has run for a while) and jammed tight.
The keeper grooves were turned and the stems were cut off.
next step (once the copper jaws are in the vise) will be to pein the
ends of the stems to keep them from loosening. Then, I will grind
the faces to 45 degrees using a cut-off wheel in the Dremel mounted in
the lathe. If I'm lucky, these valves will work out fine.
After I've finished all three valves, I will go on to something
I spent quite a while on the governor design and I think
it's ready to go into fabrication. I've also almost finished the
design of the head and will probably go ahead and machine it and the
valve guides so I can lap the valves and assemble it then get the
pistons reinstalled and get the head mounted to the base. That
sequence seems to be about the only way to get it done. That way,
I will have a definite foundation on which to build the rest of the
timing train and the governor and latch.
30 December 2014: The
first thing today was to finish making the copper jaws for the vise so
I could grip the valve stems without grunging them up.
New copper vise jaws.
material I used was some 1/4" thick buss bar that was removed from a
building that had once had a 600 Volt DC service to run elevators.
When the elevators were replaced with 3-phase AC powered
elevators, some of the 600 Volt wiring was abandoned. To keep it
from going to the landfill, I removed as much of it as I could get at
and saved it. After about 30 years, I've finally found a use for
The valves are done. I scrounged a couple of keepers from the junk pile and made one for the intake valve.
Turning falve face to 45 degrees.
Valves, springs, keepers and 10MM plug.
original plan was to turn the valve faces to near dimension then use
the Dremel cutoff wheel to finish them. After turning the faces,
I've decided that they should be fine as-is. I'll find out when I
go to lap them to the seats. As you can see in the right-hand
photo above, I did find one valve adjustment cap in my "pile".
There should have been another one in there but it must have gone
walkabout. They're easy enough to make.
Even using the
long reach spark plug, I'm going to have to mill a deep pocket in the
head so it will be able to reach the combustion chamber.
Here is another bunch of CAD drawings showing various views of the engine as it is in it's present state of design.
Back end view.
Flywheel end view.
Manifold side view and cylinder head.
I know the drawings are hard to read because of all the hidden
(dashed) lines, etc. My CAD program doesn't have a line
hiding feature or useable 3-D so we'll just have to live with it.
Another irritating chore is dimensioning the parts.
Although the program will calculate the dimensions, you have to
tell it what to dimension and where to put the dimension lines.
After all, this is the last DOS version of AutoCad. I
couldn't see investing in the newest and greatest Windows version
because this one did just fine for schematics and P.C. board layouts.
I only got into heavy mechanical design after retiring.
31 December 2014: Now I'm getting down to the dirty work, making the head out of a chunk of gray cast iron.
Getting ready to saw out the blank. After sawing, starting the squaring-up and whittling it to dimension.
really glad I finally got the power X feed for the mill. Now, I
can start it off on a noisy cut and leave it. No more hours
of cranking. My shoulders thank me!
I've been thinking of
how to hang on to the head while I machine it in the mill. What
I'll do is to drill and tap a 1/2-13 hole in the centers of each end
and screw in a short bolt. I can then use the hold-down clamps on
the heads of the bolts, leaving the entire top surface free to machine.
After machining, the bolts will be removed and when the engine is
assembled, the holes will be covered by the cam bearing brackets.
1 January 2015: More whittling on the hunk of cast iron.
Milling one surface of the head casting.
long edges are semi finished and I'm working on the second side of the
casting. The temporary bolts work fine to hang onto the
workpiece. it took all day to get this far and I still have about
0.130" to take off of the thickness and about 0.030" to take off of the
long edges. The ends are, as yet, unfinished. The "plan" is
to get the thickness to 2.000" then remove the bolts, turn the head 90
degrees, tram it and do the ends. This will take some time and
two setups. At that point, I can turn the head 90 degrees once
more, clamp it down again with the temporary bolts, square it up and
finish the long edges.
At that point, I'll remove it from the
mill, clean it up and give it a coat of Dykem so I can lay out the
holes. I'm still planning on using the mill dials to get the
dimensions as accurate as I can but will use the layout to make sure I
don't do anything stoopud.
2 January 2015: After
covering the floor with about 20 lbs of swarf, I now have a head with
two of the dimensions to specification and square. Tomorrow, I
will set the head back up in the mill and square the ends to spec. dimension.
The head and valve guides so far.
the head milling was going on, I made the valve guides. An
Aw-Shoot! occurred when I broke off a drill bit while making one of the
guides. The bit was stuck solid so the part had to be scrapped.
One of these days, I'll learn to be really easy on the old bits I
got out of Dad's shop. They are really brittle!
thinking up a valve guide seal for the power cylinder exhaust valve.
When the valve opens, there is pressure in the cylinder and
transfer port on it's way to the expansion cylinder. This
pressure will try to force it's way out past the clearance in the
guide. I think a tapered Teflon piece slipped over the top end of
the valve stem with some kind of tapered keeper will work. The
Teflon piece will be reamed to a snug fit over the valve stem and, when
the valve closes, the Teflon piece will ride up in a small vertical
clearance and wedge itself into the keeper creating a gas tight seal.
At least, that's my thought at this time.
3 January 2015: I figured out the power cylinder exhaust valve seal.
CAD drawing of the valve guide and seal.
Valve guide seal parts.
Assembled with valve.
male threaded part screws into the top of the valve guide squashing the
Teflon ring so it squeezes the valve valve stem. The drilled and
tapped bore in the valve guide uses the drill point mated with a
similar angle on the Teflon ring as a method of making it conform to
the valve stem. The male threaded part is tightened with pliers
and shouldn't require any periodic maintenance.
The head is now
to size and all surfaces are square. I just finished dimensioning
the head drawings and tomorrow, I will start working on the top surface
bolt holes and the pocket for the transfer port.
4 January 2015: Drilling
and milling on the head is started. Today, I got the top surface
holes done. Only one hole needs to be done and that's the one for
the spark plug. I'm leaving this off until I've gotten the
combustion chamber done so I don't have an intetrrupted bore job when
that is done. All of the valve ports, valve guide bores, etc. are
to be done from the other side of the head.
Top of the head with the blanked transfer passage plug.
you can see, I've got a blank ready to machine the plug that goes in
the head to seal-off the transfer passage. Because there's no way
to get that passage machined otherwise, I had to resort to "stern
5 January 2015: It
went kind of slow today. Making the plug to fit over the transfer
port was more complicated than I figured, so most of the day was spent
machining it and fitting it to the head.
The transfer port cover.
have a continuing problem with end mills creeping out of the R-8
collets I usde to hold them in the quill. This makes the depth
slowly increase no matter how tight they are. Making very light
cuts helps but that makes the job take too long. I suppose that
with a set of proper R-8 milling cutter holders, I can eliminate the
problem but the word "budget" comes up.
The tool creep is what
caused me to have to fiddle with the plug to make it fit more or less
the way I wanted. Anyway, it's done.
Just another "AW-Shoot!".
next step was to set-up to make the 2.75" diameter by 0.333" deep
combustion chamber for the power cylinder. The "plan" was to
drill and tap a shallow 1/2-20 hole exactly opposite the center of the
combustion chamber and mount the head on the rotary table chamber up.
The chamber was to be made by using an end mill and turning the
table to machine it.
The "Aw-Shoot!" came when I centered the
combustion chamber under the quill. The head is about an inch too
long to make the turn! I've got to think on this one. One
solution would be to use my big shell mill. The diameter of this
mill is somewhere around 2" so I could offset the table away from the
column and still get the chamber in the right position. As long
as the center of rotation is in the center of the combustion chamber, I
should be able to get 'er done. Tomorrow will tell the tale.
6 January 2015: Well
- it wasn't as much of a problem as I thought. I ended-up using a
3/4" end mill and didn't go to where the head hit the column.
to the outside.
Milling off the center stub.
I worked out from as close to the center as I could, I crept up on the
diameter of the combustion chamber. After getting the diameter
right, I traversed to cut off the stub. It worked fine.
Yesterday, I had made a mountain out of a molehill.
Sleeping on it made the solution obvious.
Combustion chamber with spark plug hole done.
I will work from the combustion chamber side and mill the valve
chambers, guide bores and seats and then mill out the transfer port.
There will be some second operation die grinder work needed on
the transfer port because the valve and transfer bores just barely
intersect the milled passage in the top surface of the head.
7 January 2015: I
guess my inexperience in machine shop work is showing. I thought
that finishing the head would take a long time. In actuality, I
got it finished today. All except for lapping the valves.
power cylinder end of the transfer port.
The expansion end of the transfer
The transfer port was
opened up to the power cylinder exhaust port and the expansion cylinder
by the use of a die grinder. The job's not too neat but it will
work fine. In any case, once the engine is finished, nobody will
know. I trust that you won't tell.
sleeves ready for epoxying.
Bolt sleeve in place.
After finishing the
intake and exhaust ports, the isolation sleeves for the two head bolts
that intersect a slice of the ports were cut, coated with epoxy and
driven into place. When the epoxy has hardened, I will dress the
tops of the sleeves then ream the sleeves for clearance for the head
bolts. The only way I could have avoided this would have been to
bore the ports at an angle. It just seemed like too much of a job
and was fraught with the possibilities for Aw-Shoots.
side of head.
Top of head.
still have to lap the valves and make some adjustments to valve stem
lengths but the head is now essentially finished. Having said
that, I'll probably spend a week doing the fiddly bits.
10 January 2015: The valves are lapped and the head is on the engine.
It's starting to look like an engine now.
The past couple of days have seen the head and jug gaskets cut, the rocker stands finished and the rockers in process.
not sure about how the head gasket will hold up. It's made out of
a piece of stiff, black 0.030" material I got a while back from Napa.
The new head bolts are grade 5 and I've got them torqued to the
limit of about 18 ft/lb. That torque reading is just a guess
because my torque wrench only goes down to 25 ft/lb and I set it to the
lowest setting it will click. In torquing, the gaskets seemed to
be a bit "squishy", either that or the bolts are stretching because it
took a lot of times around to get the torque wrench to snap. If
it blows, I'll have to go get some of that stuff with the metal in it.
11 January 2015: The rockers and pivots are done as well as the governor latch stand.
Rockers, etc. finished.
you compare yesterday's photo to today's, at first it doesn't seem like
anything has been done. Looking closer, you'll see I'm using a
1/4" hardened steel dowel pins for the rocker pivots and governor
latch. Note that I haven't cut the latch pin off yet. I'm
going to leave it alone until the rest of the engine's done and I see
just how far it sticks out from the rocker. Once that's done,
I'll take it off and trim it so it looks better.
had to make a bolt for the latch stand, I made it with a high-crown.
A mix of the old and the new to add a little confusion.
Next on the agenda will be the camshaft, cams and the rest of the gears. Then, I'll tackle the governor.
will still be a carburetor to make as well as an exhaust pipe. I
think he ignition timer will be located on the flywheel end of the
camshaft and will be adjustable.
12 January 2015: I've
got more CAD dimensioning to do. Among other things, I've got the
cam profiles done. I've made the exhaust open at about 10 degrees
before BDC and close at about TDC. The expansion cylinder exhaust
valve closes slightly before the power cylinder exhaust valve opens and
re-opens at BDC of the expansion cylinder, staying open for about a
turn and a half.
that the cams are not shown oriented as they would be when mounted on
the camshaft. If one or the other is rotated 180 degrees, they
will be in approximate time. The profiles will be cut with a
half-inch side cutting mill and the blanks will be mounted on the
rotary table. If you take the cam angles directly off the
drawings, you will see that they are actually larger than what the
headers say. This is because I'm figuring 0.010" valve lash.
It takes this much more rotation to get the valves to begin to
lift (close) at the indicated angles.
Now, after looking it
over, I think the drawing is screwed-up. I'll study it later this
week and make corrections if necessary.
13 January 2015: Okay, I studied the cam angles and think they will work. That's not the biggest problem, though.
I just got an email from a follower of my web page, Ron Gerlach who, in a nice way, sort of threw a monkey wrench into the project.
It was one of those Homer Simpson "DOH!" moments for me.
His point was that, especially with equal displacement cylinders, the pressure pushing the expansion piston down makes torque but it is countered by the back pressure on the power piston working in opposition. A theoretical zero sum gain. With normal frictional and heat losses, the effect is a net loss of power with the engine as it is designed.
After having slept on it, I agree with him and wish there were more engineer types around here so I could sit, drink coffee with and critique ideas. I learned early-on that, once you shed your thin skin, engineering critiques are very useful for throwing out bad ideas. You also learn to laugh at yourself.
I still plan to finish and test the engine. It should run but, unless some unrealized thermodynamic principle comes into play, not well.
I've been thinking of how to convert it into a conventional 2-banger without having to scrap the head. I think it's doable but, still, I want to see just how badly it runs before doing any modifications.
Anyway, I spent some more time in the shop today and have some of the cam and governor brackets started.
Part of the roughed-in cam, governor and top timing gear brackets.
Once I get the plate that sits on the top of the angle done, I can start drilling holes and doing the bearing bores.
14 January 2015: Moving right along,the sideshaft end of the brackets is done except for the horizontal plate for the governor.
As shown in the above
left photo, the bearing mount for the camshaft is pressed into the flat
plate. It is a slip fit into the bore in the angle bracket.
This is to assure that the gears align properly.
Cams and what you get when the drawing is too close to the
Engine being motored with spark plug in.
pays to trust the design. I was doubtful about the cam lobe
timing but decided to make them according to the drawing. They
turned out fine and the cams got installed and timed. I hooked up
the motor to spin it in order to work out some of the tightness, let
it's parts get acquainted and warm it up some.
surprised by the compression it has! I have to hold the intake
valve for the motor to start it turning. Unless it starts really
easily, I don't know if I'll be able to just pull it over by the
flywheel. We'll see.
Next up is getting serious about the
governor. Then a carburetor and ignition timer and we'll be able
to make smoke............I hope!
18 January 2015: A slow day today but I did get the aluminum parts of the governor done.
The aluminum parts of the governor.
is the part that holds the links to the middle of the ball arms (the
top "wings") and the isolation bearing which is a ball bearing that has
the wings piece pressed into it's I.D. and the large thing on the
bottom has the outer race of the bearing pressed into it.
reason it took so long to make the parts is that I had a brilliant idea
to make a video of part of the machine work like is seen on YouTube.
After setting up, shooting from various angles and general
fiddling with the camera, I said to Heck with it and made chips.
I may post part of the video as a test but, first, I have to look
at the files to see if the photography is worth the effort.
Tomorrow, I'll probably make the brass balls for the governor.
After having downloaded the scenes from the camera, I think I'll pass
on the long-winded videos. First, I've got the camera set to
maximum resolution (1280p) and the files are HUGE! Just playing
around, I used up about 10 Gigabytes of memory card. Also, if I
tried to edit a long video, my PC would load-up due to only 4 Gig of
RAM which would make it cache to the hard disk after a few scenes were
stitched together. I Think I could take naps while waiting for
the PC to catch up. I may experiment with the camera set to 720
and see if the files are manageable but for now, I've deleted the clips
I took earlier).
19 January 2015: This
was another one of those days where everything seemed to go very
slowly. The reason is that the parts made were kind of "fiddly".
First, I made the governor balls.
Cut bar stock to length.
Drill and tap 10-32.
Turn and thread 1/4" rod 10-32.
Screw blank onto
Back up and make a stiffening spacer.
Move fixture back and forth
while feeding slide.
As you can
see, I wasn't happy with the look of that hunk of brass hanging out on
the end of the quarter inch rod. To fix that, I faced and drilled
a piece of 5/8" stock. Then, I partially threaded the ball on the
rod. After slipping the drilled stock over the quarter inch rod,
I pushed the works against the chuck jaws then tightened the chuck.
Last, I turned the blank, using the threads to pull it up tight against
The fixture I used to make the balls is something I
thought up a while back. It is set so from left to right, the
tool tip is the distance you want the diameter of the ball to be.
Then, the fixture (mounted on the cross slide) is moved so the
handle and tool tip are straight back. At that point, the
carriage is moved to where you want the center of the ball to be and
the carriage is locked down. After that, turning the ball is
simply a matter of feeding the cross slide a bit and cycling the handle
from left to right. The drawback to this tool is that you can't
get all the way around to the chuck side of the ball. I suppose I
could modify the tool holder and grind a tool that would allow me to go
nearer to the chuck but I haven't been compelled to do that yet.
Finish turning ball.
After turning the base square.
The finished balls and almost finished
As you can see in the
above left photo, the sphere is less than complete. After getting
as far as I could go with the fixture, I removed it from the lathe, put
the compound back on and used a turning tool to square-up the flared
end. A bit of sanding and polishing got the worst of the
tool marks out. The last thing (non-trivial) I did was to make
the swing arms for the balls. As you can see, I've lengthened the
thread on the ball end and will use the lock nuts to adjust the length
so both balls are an equal distance from the vertical governor shaft
when the balls are all the way out. The only thing remaining to
do after setting the lengths equal is to locate and drill the pivot pin
holes in the swing arms.
Tomorrow, I will work on the top arm
and the arms that go between the ball arms and the center rising
portion that I made yesterday. Oh, yes. The pivot pins will
be some 12-gauge copper wire made into rivets and peined over to hold
them in place.
20 January 2015: As you can see, the governor is together.
The finished governor.
now, there's no linkage or speed adjust spring so, when I motor the
engine, the balls go all the way out. Also, as you'll see in the
movie, they stay out after stopping the engine. One reason is, of
course, the spring and the second is that the linkages are a bit on the
stiff side. If, while motoring, I pull down on the brass rod
beneath the governor, it will act like it should, bobbing every time
the engine comes up on compression. From how hard I have to pull
down to keep the balls in even at low RPM, I think it will be plenty
powerful to drive the linkage to the latch.
23 January 2015: Well, yesterday something happened in the shop that caused an "AW SHOOT!".
it's always the last operation when the tap breaks off. After
fiddling with it for several minutes, I scrapped it and started over.
That doesn/t happen often but when it does, I am compelled to
utter some choice words. The rest of the governor linkage parts
went relatively smoothly. It consists of several small fiddly
and latch linkage.
bunch of stuff that took a lot of time but the governor is all done and
seems to work although it is still stiff. Notice that I had to
add a compression spring on the latch rod in order to make it work at a
high enough speed that the engine should run. Playing with it, I
think it will latch-out at about 500 RPM which should be a decent
speed. Once it's running and tweaked, I might be able to slow it
Flanges for intake and exhaust.
The last thing I did today was to make the flanges for the intake and exhaust. They are made of 1/8" hot rolled steel.
The exhaust, such as it is, was a piece of cake. Some conduit from the junkpile and some welding was all it took.
The mixer is a bit more complicated. It, also, is made from junkpile stuff.
Exhaust and part of the mixer are done.
mixer tube is a piece of 1/2" pipe. I turned down one end for a
press fit into the flange. The I.D. of the piece of pipe was
bored to clean it up. The other end was faced off. I made a
throat out of a piece of aluminum bar. It was turned to be a slip
fit in the tube. The port is 3/4" so I drilled through the throat
with a 3/8" drill. While the throat was in the lathe, I set the
compound to give a 3/4" long taper from nearly the O.D. to the 3/8"
bore on the inlet end and did the same thing for about 1/2" on the
The jet is located right at the neck of the throat.
I'm hoping there will be enough venturi effect to draw fuel but,
if not, I will make a choke plate for the air inlet. The fat spot
soldered into the fuel line has a 1/8" bearing ball in it to act as a
I still have the needle valve and needle valve
packing to finish. Rooting around in my plastic stuff, I found
some Teflon "O" rings. I think I can make the packing out of a
piece of one of them.
25 January 2015: All that's left to do is the ignition. The mixer is done and I've made a fuel tank for it.
Mixer and fuel tank.
put gasoline in the tank and, without choking, it will draw fuel from
the tank and I can smell it in the exhaust while motoring. This
is a good sign that I guessed at least close to right on the venturi
and jet size.
ignition timer will be at the flywheel end of the camshaft. As
yet, I haven't decided whether to use a Hall Effect I.C. or a reed
switch to sense a magnet or a simple contact arrangement. I do
want to have the ignition timing adjustable on the fly so it won't be
just dead simple. I will do a battery saver later if the engine
is worth the trouble. If I get lucky and everything goes well
tomorrow, I -could possibly- have the first smoke (or not!) event
26 January 2015: Not
quite ready yet. The ignition's coming along and, once the glue
sets, I can put it together. I decided to use a magnetic reed
switch for the timer and, after breaking a couple of those little glass
enclosed buggers (0.080" diameter by about 1" long), think it's going
to be all right.
No photos of this part. They'll be taken after the ignition is installed.
Unless something comes up, tomorow will be the day of reckoning.
27 January 2015: After
finishing the ignition, The first start attempt was made. During
the first motoring with ignition and fuel, it fired a few times then
several problems popped-up.
First, the spark plug, which
was one that was previously used on the 30-60 engine, fouled out.
After changing the plug with another used one, it would fire more
or less consistently with my finger over the air inlet. This
necessitated a pause while I made a choke for the mixer.
after installing the choke, the engine tried to run but again quit
firing. This time, the problem was in the timer. The magnet
was just a bit too far from the magnetic reed switch for reliable
operation so I removed the "rotor" which mounted the magnet and
machined a bit off of the hub to make it pass closer to the reed switch.
time, it ran well enough to almost go without the motor assisting.
I believe one of the problems is that the flywheel (the original
pulley) isn't heavy enough to allow the engine to carry over after
unlatching the exhaust valve. It may improve as the governor
stiffness goes away, allowing the unlatching to occur more rapidly.
in all, I'm heartened by the willingness of the engine to run.
Further tweaks and fiddling will doubtless have it running on
Here's the movie I made. A note about this
movie. I think I'll stick to shorter flicks in the future.
My 'puter needs a lot more RAM to be able to process long or
complicated videos. To process this one, it took about an hour to
convert the edited work into a movie. Editing was also VERY slow.
First Run of The Compressor Engine.
I quit videoing, I did some more fiddling and actually got the engine
to run on it's own, belted to the motor but with the motor turned off.
I believe the mass of the motor rotor adds just enough flywheel
effect to kallow it to keep running.
28 January 2015: I got a photo of the choke I made yesterday. Here it is.
is the start of the fiddly bits to get it to run well. First off,
I decided to re-work the check valve because I was unable to make the
original one seat properly.
New check valve.
new check valve made the engine fire more consistently but I still had
to keep the choke pretty much closed to make it run reasonably well.
I got to thinking about having to use so much choke to get it to
run and decided to make a new venturi (throat) for the mixer.
New venturi (left) Old venturi (right).
original venturi tapered to a bore of 0.375". My thought was that
the venturi was not small enough to produce sufficient suction to draw
fuel properly. I made a new one with a bore of 0.250".
After a bit of fiddling with mixture, I found I could run it with
the choke all the way off. Because of this, I removed the
external choke and plan to use the thumb method to choke it for
With the new venturi and improved check valve, the
engine runs pretty well. For a while, I could completely turn off
the power to the motor and the engine would drive it but, because of
flywheel issues, if it missed a single lick, everything would come to a
A couple of issues came up, though.
The flywheel (pulley) is not a very good fit on the shaft and,
even with a key and setscrew, it works loose, causing an ominous knock.
I finally tightened the heck out of the set screw and it
seems to be holding. A new "real" flywheel with a gib key looks
to be in the future because this one just doesn't have enough mass for
the engine to carry-over well.
The other issue is ignition.
First, it was spark plugs. I need to get some new ones!
To get along, I put a spark gap ("intensifier") in the plug wire
which made a bad plug fire reliably. Then, along with fighting
fouled spark plugs, the ignition timer quit working yet again.
The reed switches have a tendency to stick closed. I think
the little reed switches are going to go into the "not such a good
idea" file. The space for mounting is so tight, I think bending
the leads causes them to get sticky. That ended up being what was
the problem. The ignition would quit and I could give the timer a
whack with a screwdriver handle to make it come back to life.
In the works is a simple contact and wiper arrangement, guaranteed to be mostly foolproof.
31 January 2015: Not
a whole lot to report. Other things interfered. Today, I
got it to run consistently but it still didn't like the light flywheel
so I grabbed the heavy flywheel I made for The Mystery Engine. I
had to bush the wheel from 1" bore diameter to the undersized 3/4" of
the comperssor. The bushing was sized to be a press fit in the
flywheel and I broached a keyway for a gib key in the bushing.
The new flywheel installed.
had also reworked the ignition using a magnet to attract a small piece
of steel shim stock to a contact. When I belted the engine up and
started it, it ran better than ever. I flipped the belt off and
it ran happily. At least for a while. Then the ignition
timer quit again. I don't know what is going on. The
ignition must have a jinx on it! If it doesn't start behaving in
a couple of days after I put a bigger magnet on it, I think I'll revert
to a simple rotating contact that is grounded at firing time.
4 February 2015: I havent
done anything on the engine for a few days. Last time out in the
shop, I retimed the timer with the bigger magnet. The engine ran
very well, not even needing to be choked for starting. It was
running along fine and, after a few minutes, I went to check to see if
it was getting too hot. I must not have been paying attention
because all of a sudden, something snatched at a finger.
drew back my hand, I was missing most of the small joint of my left
middle finger. It had gotten caught in the top bevel gear with
predictable results. After finding the piece that was torn off
(unsalvageable), I shut down the engine, closed up the shop and took a
trip to the emergency room. The next day, I went to the hand
The Law of Averages must be catching-up with me and I guess you can now call me "Mister Stubby".
The bad news is that I'll be out of the shop for a while. The good news is that I've learned a lesson in safety.
14 February 2015: I
got back into the shop for a short time today. Right before the
accident, I was working on a spark saver. This is a contact that
is grounded when the exhaust valve is open. This disables the
ignition when the governor has latched-out the exhaust valve.
you can see, the spark saver contact is very simple. It is just a
piece of music wire that is mounted on the head using insulating
washers. It grounds when the exhaust valve is open by touching
the extension of the latch pin.
The next thing I tackled was the
starting crank. I found a piece of scrap that was about the right
size and whittled it until it fits over the flywheel hub. I then
milled a slot to engage the gib key in the flywheel.
Disc in place.
will make a ramp, shown inked in the left photo above, to kick the
crank off of the flywheel hub when the engine starts. At least
that's the way it's supposed to work. Of course, there will be a
bar bolted to the piece shown and a handle mounted to the bar.
Note that the key is in the down position at the beginning of the
21 February 2015: I haven't been getting much shop time lately. Today, I finished the starting crank.
The starting crank.
one of those things that seems so simple. As it is, it doesn't
work worth a hoot. The ramp I "whittled" works well to disengage
it when it goes over compression but it also disengasges when pulling
it up on compression unless I'm VERY careful. I think I can file
a bit on the flat that engages the gib key to make it sort of hook the
key. Maybe that will work.
Oh, yes. I modified the
latch rod. It was wearing on the sharp edge of the latch which is
made from a very hard dowel pin. The fix (not tested yet) was to
drill and ream the end of the latch rod (drill rod) that
engages the latch and press in a 1/8" dowel pin with the engagement end
squared-off. I also broke the sharp edge on the latch that was
cutting the latch rod.
2 March 2015: I haven't been doing much lately but today, my finger felt like going out to the shop so I did.
didn't get much done except to make a crankshaft extension for the
starting handle. With that finished, the engine started easily
and ran well. As usual, I thought I could improve matters so I
fiddled with the timing. All along, I've had it set to fire right
at Top Dead Center. Thinking it would run better with the spark
occuring about 10 degrees early, I made the adjustment and promptly
found out that it didn't like any lead at all and bent the arm of the
starting crank to tell me so.
The result of too early ignition timing.
can see the bent handle above. You can also see that I've changed
the "timing" of the crank so it goes over compression before the handle
is vertical.. Much better. The arm of the crank is some 0.190"
round edge steel I had sitting around. I think I'll change it to
1/4" or 3/8" to give it a little more rigidity.
I returned the timing to TDC and the engine said, "thank you very large".
12 March 2015: I've
been goofing-off a bit lately. Today, I "improved" the starting
crank. It now sports a 3/8" arm and I've also advanced the timing
of the crank so it goes over TDC with the arm at around 10 o'clock.
Much better. I also made a plate to cover up all the holes.
The "improved" starting handle.
running it for a while (until it got warmed-up), I decided that it runs
fine and that I shouldn't try to improve on it. If I do, I stand
the chance that it'll never run as well as it does now.
at the photo, I think I've screwed-up. I believe there were only
supposed to be three 2 X 4's. If it's wrong, I'll simply do a
little artistic scroll saw work. The extra wide footprint will
keep the engine from jumping around so much. Bondo IS for
woodwork, isn't it?
16 March 2015: After giving the glue a day to dry, I did some more whittling and sanding and have some paint on it.
Skid coming along.
color is the mixture of the remains of some metallic lavender and some
aluminum auto paint left over from touching-up a previously owned
motorhome. It was about ten years old so it was time for it to be
The piece below the skid is the spacer that goes
between the engine and the skid so the flywheel will clear the skid.
It's presently soaking up some rays while the glue dries and I
should get it it sanded, painted and mounted-up tomorrow.
17 March 2015: It's on the skid now and ready for it's last screen appearance. The video will be made later in the week.
Ready for prime time.
I got the engine mounted on the skid, I had a "Dagnabbit!" moment.
I discovered that the crank handle was about three quarters of an
inch too long, which made it hit the skid. A little sawing,
drilling and tapping fixed that. The crank is pretty short now
but I can still turn it over compression.
When I did a little
test run, it would run for a few seconds then act like it was out of
gas. A bit of detective work found the culprit. When I made
the gas tank cap, I forgot to drill a vent hole. I guess that
this time, I tightened it more than before and created a seal in the
threads. A number 60 drill fixed that!
7 April 2015: Wow!
It's been a while since I've added anything. Today, though,
I finally got around to making the final movie of the engine so I guess
I can consider this project done.After making the movie, I took it's
After about ten minutes of running.
Here's the last movie. I've got to admit that, for an engine that essentially wastes one cylinder, it sure runs nice.
9 April 2015: In
response to a numerous request from my friend Denis Basson of Adelaide
Australia, I have made a guard for the gear that took the tip off my
This one's for Denis! _______________________________________________________________________
13 April 2015: Well,
Denis saw the guard and thought it was ugly. He said it reminded
of the mask that Hannibal Lechter had to wear in "Silence of The Lambs".
Picky Picky! It was a good comparison because it keeps the
gears from eating any more body parts. Anyway, I hope you're
happy now, Denis! Just for you, I made another guard for the
lower gear. The plastic is scratched but that's the way it came
off the shelf.