Hart-Parr 30-60
Semi-Replica Engine
Go To Part Two
Mounting The Engine, Making The Flywheel And The Fiddly Bits.

Go To Part Three
Further Development and Mounting on Skid for Display

Since I've always wanted a REALLY big 2-banger "popper" engine but don't have either the space or the bucks to get one, I'm going to build a sort-of replica of the engine in a Hart-Parr 30-60 tractor. In case you're unfamiliar with the original Hart-Parr 30-60 tractor, here's a YouTube video:
The 60 HP engine used in that tractor has a bore of 10 inches (254 mm) and a stroke of 15" (381 mm), giving a swept volume of 2356.2 cubic inches (38611.2 cc).  A nice little engine.

It has a flywheel that is 57-1/2 inches (1460.5 mm) in diameter, weighing-in at a mere 1000 lb (453.59 kg). 

The Hart-Parr 60 HP engine runs at 300 RPM and develops, natch, 60 HP.
Since my shop equipment is just a slight bit too lightweight to handle a full-size version, I've decided to scale it down to about 1/6th size.  In actuality, I've taken several liberties with the design, ending up with a bore of 1.75 inches (44.45 mm) and a stroke of 2.5 (63.5 mm) inches, giving 12.026 cubic inches (197.07 cc) displacement.

I'll make a rough guess that the horsepower of my semi-replica will be around 3 to 4 horse at somewhere in the neighborhood of 700 RPM. 
An interesting feature of the Hart-Parr engine is that it is hit and miss with one cylinder designed to cut-out at a slightly lower RPM than the other, giving it a really weird cadence when it is at light loads. 

The Hart-Parr has hemispherical combustion chambers but mine will have "conical" chambers due to the limitations of my shop.  The valves are both powered by the cam through a single rocker. 

As far as I can tell, the valves both use one leaf spring which pivots between the valves.  When one valve is open, the other is held shut more tightly.
My engine will use the same arrangement.

Notably different from the Hart-Parr is the cam drive and governor arrangement.  I've tried to find some 1:2 skew gears that are large enough for my crankshaft to sideshaft link and some 1:1 miter gears for my sideshaft to camshaft link.  They are VERY pricey so they are a no-show.  I will use 3/8" pitch 20-40 tooth and sprockets and roller chain to do the job.

The Hart Parr engine uses a belt driven flyball governor and, since I can't figure out a practical way to drive a governor in the space limitations I've imposed, I've come-up with a governor that will be built into the cam sprocket hub.

Ignition will be via a magnetic Hall-Effect transistor and two magnets.  The coil will be one that has both secondary leads coming out (like a Harley-Davidson or Onan 2-banger coil).  One plug wire will go to each plug and to the distributor.  My distributor will simply ground the tower of the non-firing plug.

I'm not sure just when I'll start the actual cutting of metal on this project.  The raw materials (shafting, cast iron, bushings, bearings, etc.), so far, are adding-up to around $630.00 so this engine is going to be one of my more expensive endeavors.  I still have other materials to purchase plus the shop charge for water-jet cutting out of the blanks for the rods, rocker arms, flywheel, etc.

Now, my plan for displaying this engine (if it turns out good enough to do anything with) is to re-power The 2009-1/2 Algore Edition Hybrid Green Hoyt-Clagwell tractor with it.  Because I will ditch the "Hybrid Green" part, I had to design the engine to rotate in the opposite direction of the original so I can use the transaxle (out of a Sears Suburban garden tractor) to best effect.
If it does turn out to run well enough, I'll make a replica of the Hart-Parr 30-60 radiator and stack.  I'm not so sure of using oil cooling, though.
26 November 2011:
Now, don't git yer bowels in an uproar!  I ain't started yet!
8 December 2011: I've got most of the steel, bushings and other parts gathered and am waiting for the shop to schedule the waterjet cutting of the parts.  THEN, I can get started on making swarf.
13  December 2011:
While awaiting the waterjet cutting, I started making parts.

One finished main bearing block, one blank.

Both finished main bearing blocks.

As you can see, I'm using thrust face bronze bushings for the main bearings.  The crankshaft diameter will be one inch.  The blocks will be a tight slip fit in the engine frame.  The bushings will be secured in the blocks with bearing set Loktite.  I'm using lip seals to keep the oil inside where it belongs.  I designed these parts to be able to accommodate a different type  of bearings if necessary.  I figure if the mains don't hold-up, it won't be an earth-shaking project to re-machine the blocks for caged roller bearings and use the same seals.
22  December 2011:
I'm working on the governor and the farther I get into the governor, the less I like it.  It's just about finished - leaving only the final touch-up and fitting.

Governor parts laid-out.

Governor assembled.

The governor base is the flange of the sprocket on the cam end of the timing chain.  Slots milled in the sprocket hub are to fit the four weights.  The weights have 40 degree cam faces that engage the inside of the governor cover and ring. As the engine speeds-up, the weights are thrown by centrifugal force against the lower side of the governor cover and force it away from the sprocket.  This movement is supposed to force the latch rod into position to latch one of the exhaust valves open.  A further slight increase in speed is supposed to latch the  other exhaust valve open.

Governor at rest.

Governor at 400 RPM (800 RPM crankshaft speed.

Although the governor does work as shown above, I don't think it will provide enough force to move the latch rod.  I'm going to go ahead and finish it up and, if it doesn't work, I'll figure out something else.
29  December 2011:
Since I'm still waiting for the shop to schedule the waterjet cutting, I decided to look into getting a toolpost grinder so I can machine the crankshaft.  Wow!  Even used, they aren't cheap.
Since I'm already over budget on this project, I figured I might as well spend some time to see if I could build my own toolpost grinder.  Looking in the trusty junque, I found the motor out of a deceased vacuum cleaner.  I figured it would have enough torque to turn the wheel.  Because these motors are series wound, unless you have a steady load on them, they tend to speed up.  A LOT! Anyway, I decided to try it and see how bad it could be.


Testing the grinder.

I mounted the motor using a cut-up section of rectangular tubing.  The base was drilled for 1/4-20 bolts, the heads of which were ground so they would fit into the T-slots of the carriage.  A mandrel was made to adapt the shaft of the motor for mounting the wheel. Using a variac (variable voltage transformer) to control the voltage going to the motor (and the speed), I chucked-up a piece of 1" shafting and, after dressing the wheel, made some cuts.  The wheel, off of a junked el-cheapo grinder, is not going to be good enough.  The balance is poor and it makes a relatively rough surface.  

The speed thing is a real problem.  The wheel is rated at 3,600 RPM and the motor really wants to go about 15,000 RPM.  If I let it do it's thing (even at low voltage, the grinding wheel would explode from the centrifugal force.  I may have to dig-up some electronics, make an encoder for the stub end shaft and use something like a triac to vary the phase angle of the 120V to regulate the speed.  An advantage of a speed regulator would be to ensure a constant, safe speed for the wheel regardless of the depth of cut.
Remember, "Science is always working for you at Hoyt-Clagwell & Company".
2 January 2012:
Now that I've got working reasonably well, I'm back in the shop making swarf. 
  Today I squared-up and sized the water jacket and ground the welding vee.  This is the second piece of 1/4" wall rectangular tube I've worked on.  The first one, bought at a local steel supply house was burned off a larger piece.  I specified the exact length I needed, figuring they'd cut it so it would be at the ordered length after I got it sized.  Wrong!  I got one end squared-up and flipped it in the mill.  I made one flycut pass to just tink off the high spots then measured it.  Drat!  It was gonna be 1/8" short once it cleaned-up.  Took it back to the steel supply and they gave no argument and replaced the piece.  I think I'll order everything a bit bigger next time.  Live and learn.

The semi-finished water jacket, ready for drilling the water inlet and outlet.

Next up, the cylinder liners.
3 January 2012:
First, I cut the foot-long piece of 1.5" I.D X 2.5" O.D. steel tube to rough length.

One liner cut to rough length.

Then, I had to square one end up and clean up the O.D.

Cleaning up the O.D.

After turning the seat step, boring was started.

The design calls for the O.D. of the liners called for a 2.5" dimension.  Again, I was outsmarted.  The rough O.D of the pipe was actually about 2.480".  Okay, since I hadn't started on the headers that the liners slip into, I can modify the dimensions.  After cleanup, the O.D. was 2.460". Since I had to hang the liners off of the 4-jaw chuck, I couldn't turn the O.D. in one operation, so after turning it as far as I could, I then cleaned-up the end.  I reversed the liner in the chuck and again painstakingly centered it and carefully banged it parallel to the ways.  Because I did the "painstaking" part in setting the liner in the chuck, when I finished the O.D., there is just a noticeable look in the surface where the two diameters meet.  I think it's because the turning of the ends is in different directions.  I can measure maybe a couple of tenths of a thousandth between the diameters.


Finishing the boring.

The step at the bottom of the cylinder is 1/4" deep and it is planned to be a light press fit in the crankcase-end header.  The bore diameter is 1.750". Of note, my boring bar is home-made using the "ignorance is bliss" school of toolmaking.  I just grabbed what was hanging out in the steel junk and knocked it out.  Surprisingly, I can take 0.010" cuts with minimal chatter with it hanging out there six inches. Tomorrow, I'll finish the second liner and make plans to get the steel to the shop where the waterjet cutting is to be done.
4 January 2012:
The jacket and liners are finished.

Liners and water jacket ready for the header plates.

I'm not sure what I'm going to do next.  Later in the week, I'll deliver the steel to the machine shop for waterjet cutting.  In the meantime, there are other parts I can start on.
8 January 2012: I'm back at it and now have the pistons mostly done.

Pistons and liners.

It took all day to do the pistons so far.  All that is needed to do to finish them is to bore the wrist pin holes and drill the four radial oil control ring vent holes.  The top two grooves are for 3/32" compression rings and the bottom is for a 1/8" oil ring.  Initially, I will only put compression rings in the top grooves.  If blow-by is excessive, I can tear it down and add the second compression rings. The pistons were turned to give 0.006" of skirt clearance.  In the ring area, I turned the diameter down 0.020".
9 January 2012:
Short day today.  I got the oil return holes and wrist pin bores drilled and reamed for a press fit with the wrist pins.  

Pistons, pins, pin bushings and bore protectors.

The wrist pins are actually 3/8" hardened steel dowel pins which are manufactured a little oversized for press fit in 3/8" bores.  I needed something to protect the bores in case a wrist pin decided to wander out of position so the brass junkpile yielded a short length of 3/8" O.D. brass pipe which I cut into 0.085" thick "plugs" that are a press fit in the wrist pin bores.
11 January 2012:
Yesterday, the piston rings came in so the first thing I did today was to check out the ring grooves and file the end gaps.  The rings are now stored securely in the bores waiting for the rods to get done so the piston/rod assemblies can be finished.
Then, I made the Cam bearing blocks.

Cam bearing blocks

Cam bearing blocks with bushings itemporarily in place.

I kinda messed-up.  I forgot that I had ordered a piece of 1.500" round leadloy bar stock, so the first thing I did was to root in the junkpile to find something that was 1" thick and big enough to whittle into two 1.5" diameter pieces.  I found enough for one and figured I'd have to order more steel so I made the one block (shown on the right).  The piece I had wasn't quite big enough so some edges show but this detail is not important.THEN, after finishing the first part, I happened to glance into the box of materials and BEHOLD!  There was the foot-long hunk of leadloy.  The second bearing block (shown on the left) was a LOT easier to make.
12 January 2012:
Today, I decided to go ahead and do the cams.  


Cam timing diagram.

As you can see, the timing's not radical.  The exhaust valve opens at 165 degrees ATDC and the exhaust valve stays open for 195 degrees.  The intake valve is open for 180 degrees with compression being another 180 degrees.  The cam shape is compensated for the 0.625" diameter of the cam followers.  The followers are small ball bearings out of the junkbox.

cam blank

The cam blanks

cam blank

Profiling the cam



A finished cam

I goofed with the original drawing.  The original CAD had the camshaft being 0.625" in diameter.   A subsequent revision increased the diameter to 0.750" to add some stiffness.  This caused me to have to revise the drawing and dimensions in the shop.  It  all worked-out anyhow.  Tomorrow I will do the second cam.
15 January 2012:
I made the second cam a couple of days ago and today, I started on the head.
12 January 2012:
Sawing-off the blank
Squaring-up and sizing the blank.
Now to size.
The head is going to be complicated.  The combustion chambers, as you will see later are conical (as close as I can get to hemispherical with my machinery and skill). 

Combustion chamber side partially done.
The head bolts (all thirteen of 'em) are 10-32 socket head cap screws.  The two largest holes are the bores for the exhaust valve and guide.  The intake valves are canted down at 45 degrees.The smaller holes just above them are 1/4" diameter holes for the spark plugs to communicate with the combustion chamber.  The plugs are to be vertical, screwed-in from the top of the head.

The plan for the combustion chambers is to mount the head in the rotary table, centered on the exhaust valve bore.  The mill quill will be tilted to 45 degrees and, using a 3/4" milling cutter, the table will be turned slowly as the head is raised.  This will make the conical shape which will be centered on the exhaust valve.  The diameter of the cone at the gasket surface will be 1.75", the size of the bore of the engine and it will taper down to slightly above the exhaust valve seat.
16 January 2012:
I got more done today than I thought I would.  The combustion chambers and the valve bores are done.
Tracing the final combustion chamber diameter.
Finishing the combustion chamber.
Reaming the intake valve bore.
The location of the combustion chambers and valve bores is critical so a lot of time was taken checking and double checking the setups before making any swarf.  

I'll have sore arms tomorrow because I put about a million turns on the rotary table crank.  To get the milling cutter to cut clean, I had to take a lot of 0.015" cuts.  At one turn of the table to the cut and a bunch of turns of the crank to make a turn of the table, I think it's broken-in now.

This side of the head is nearly done.
The valves are only going to be a little over 0.500" in diameter so the engine isn't gonna be a racing champ by any means.  I figure it will breathe well enough to run pretty well.
19 January 2012:
The head is almost finished.  The valves must be turned down, the guides made and seated.  I still have to figure out and design the valve leaf spring perches but there's plenty of real estate there to do it.
Spark plugs in place.
spark plug
Plug, from combustion chamber.
In the above left photo, you can see how the spark plugs work into the design.  The spark will be back in a hole but that shouldn't affect the running.  

The exhaust ports are shown on the far side of the spark plugs.

Plug, from combustion chamber.
Intake runner to be plugged.
The intake ports are connected via a 1/2" runner.  In the above right photo, you can see the drill entry end of the runner.  The runner stops at the second intake port.  This runner will be plugged.  The port for the mixer is shown in the above left photo.  

I think the hard parts are about done.  The rest is simply making the parts and assembling them.  That doesn't mean there's not a lot left to do.  I figure a couple of months may be required to have it running.
20 January 2012:
Started on the valves and guides today.
Turning valve down.
Valve before and after re-sizing
Turning valves down is kinda tedious because the stem is long and limber.  I've found that taking small cuts with a dead-sharp carbide bit helps.  The original stem diameters was 0.250" but, I couldn't leave it at that if I was going to turn the valve heads down to 0.550".  I turned the stem to (0.171") and was then going to make the guides and check the fit when they were reamed to 0.1719 (11/64").  If the fit was good (not knowing exactly what my cheap reamer would give me), then I'd do the rest of the valves.

I got started on a guide when an "AW_SHOOT!" occurred.

Dang!  The cross slide leadscrew nut went and gebusted!
I was turning the O.D. of the first guide when the cross slide lead relaxed.  Turning the handle did nothing.  Being an astute individual, I surmised that something was out of order.

When I took it apart, I found that the nut for the leadscrew had broken.  This is another of those maddening things about Chinese machinery.  Some bean counter decided that they could save a nickel or two by using diecast parts instead of brass or steel.  You can see the result.  I've epoxied the nut back together and am going to use a slightly longer mounting screw that gets into the thread in the body of the nut.  I hope it lasts until the replacement part arrives.

It may be a cheap lathe but there's nothing cheap about replacement parts.  That two-ounce nut runs about $12 with about $12 shipping!  If I had a left-hand 1/4-20 tap (close to the metric size of the original screw and nut, I think I'd get some precision 1/4-20 all thread and make one outta brass.

I'll see tomorrow if the fix will work at all.  If not, I'll be taking a vacation from the project until I get the part.
21 January 2012:
The "glue job" didn't work so I fell back to Plan B.  Plan B consists of re-tapping the M6-20 thread to 1/4-20 (a little bigger) as far as I could go without interfering with the leadscrew.  That gave me about 1/4" more thread to work with.  Then, I cut a brass 1/4-20 flat head screw until it ----almost---- touched the leadscrew thread.  It's now back together and, so far, is working.

The valve guides are made and have been pressed into the head.
valve guides
Head with valve guides installed.
The guides were reamed to 0.1719" and ended up a little oversize but, after pressing the guides into the head, the fit was very nice.

I started on the other three valves.  The head diameter and the head thickness are to size.  Tomorrow, I will turn the stems and cut them to rough length.  I will hold off the final length and the retainer grooves until I've got the cam and rockers done.  Then I can get the fit optomized.
22 January 2012:
The valves are now resized and lapped to the head.
Turning the valve stem.
The head with valves installed.
There's another fiddly job done.  Tomorrow, I'll call the machine shop once more to see if the steel parts are cut.  If not, I can work on the rocker bushing blanks and design the valve spring arrangement.
23 January 2012:
Today, I got a couple of the little things done along with making a better homebrew toolpost grinder.

Plugged end of intake passage.

Cam stand mounting pads.
I made a steel plug for the drill access point of the intake passage.  This hole was drilled through the head and intersects both intake valve ports.  There is a hole drilled from the outside center of the head perpendicular to the passage that intersects it.  The mixer will be mounted to this passage.

Another little job was making the mounting pads which the cam stands are to be welded.  They are marked for positioning the stands before welding them.
24 January 2012:
I've made a new toolpost grinder.

The new toolpost grinder doing a test cut.

The finished test cut.        
With a decent grinding wheel and motor, I think it will suffice.  I need to be careful how much I take off per pass because I've already found that the wheel wears fastest at the leading edge (duh!).  I suppose I'll need to get to within a thousandth or so of the finished diameter then dress the wheel flat before taking off the final amount.

This worked out well because the shop called and said they'd be doing the cutting this afternoon.  After I got the full-price quote for all of the cut pieces, I decided to only do those that I have no way of doing in my shop.  This engine is getting to be very pricey!
The flywheel was to be cut out but, because of the amount of cutting machine time, I'll have to do it with my mill.  Now THAT's gonna take some time but the upside of it is that I'll have to purchase some new carbide cutters and they should be good for much more work after the flywheel's completed.

The crankshaft will be blanked out as well as the rocker arms and the connecting rods.  They are the most complicated shapes that I have to cut and are cut from the thickest steel.  The crankshaft is cut from 1.250" thick steel, the rods are cut from 0.625" steel and the rocker arms are from 0.375" steel.  The 0.250 parts include the two cam towers which are complex shapes but since the metal's relatively thin, I can cut them out on the bandsaw.  The rest of the parts are simple rectangles and squares with some large diameter holes.

25 January 2012:
Yesterday afternoon I picked up the parts from the shop that does the CNC waterjet cutting.  I'm going to give the shop a plug here because they are so nice to work with.
The shop is:
Advanced Machine and Laser
1010 Aberdeen Loop
Panama City, Florida 32405
(850) 248-4000
[email protected]
The owner is David Dominik and the guy who did the cutting for me is Sam Bouldin.
Advanced does a lot of CNC machining and their water jet cutter can make something as big as a bull gear for a Hart-Parr 30-60, or even larger.

Okay, now that I've got the shameless plug out of the way, we can get back to our exciting adventure into metal whittling.

The crankshaft blank.

Centering the crankshaft in the 4-jaw chuck.
I made the CAD files for each part, adding 0.060" to all dimensions to account for the widening of the kerf at the bottom of the cut.  

One end of the crankshaft blank was carefully center punched then it was mounted in the 4-jaw chuck and centered at the chuck end with a dial indicator. After bumping the crankshaft until the center punch mark was exactly centered on the live center, the center was removed and the drill chuck was put in the tailstock.  Using a drill center, a center hole was drilled in the end of the crankshaft.  The chuck was removed and the live center was snugged-up.

Doing the "clunkety-clunk" part.

Taking the finishing cuts.
At first, I thought I'd need to grind the main bearing journals but decided to turn them to close to finish size.  The turning went so smoothly, I just finished the journals by taking very light cuts until the main bearings would just -barely- start onto the shaft.  Using 400 grit emery paper and mineral spirits, the journals were carefully taken down to size.  In doing this step, the surface finish was improved.  The mains now have about 0.0005" clearance and I figure that, with running, they will end-up having about 0.001" oil clearance.

Mains finished with the main bearing blocks in place.
Above, you can see the crankshaft with the main bearing blocks in place.  The bronze bushings are a light press fit in the steel blocks which will fit snugly into bores in the crankcase sides.  I have left the distance between the thrust surfaces on either end of the crankshaft at a larger distance than the drawing shows.   When doing the final assembly of the engine, I can remove enough steel from these surfaces to set the end play.

Tomorrow, I will make the offset arms and, maybe start on the throws.
26 January 2012:
Progress was slow today.  To make the offset arms for machining the crank throws, I had to cut-up a really nasty hunk of 3/4" steel that had been torched off of something.

The offset arms with the driving pin.

Mounted on the crankshaft.

And in the lathe.
Now that I have the crankshaft with the offsets in the lathe, I'm trying to figure out how to turn the throws.  In the right-hand photo, I've got a big carbide bit in the tool holder.  If I end-up using it, I'll have to mill about 1/4" off of the bottom of the bit to get it centered vertically.  I may try some oddball configurations of the grinder also.  I know it can be done with what I've got, it's just got to come to me.
27 January 2012:It took all day but I got one of the throws turned.  Doing the rods is chatter city so I have to take small cuts and LOTS of 'em.

Giving myself a little room for the compound.

Turning a rod journal.
After thinking on it for a while, the first thing I had to do was to remove a little of the extra metal from the radiuses of the main bearing journals.  This gives me enough room to move the compound in enough to work on the rod journals.

To get the rod journal from square to round, I used an old brazed carbide bit, taking small cuts  until the journal was almost round.  Then I switched to a HSS bit.

I had a 1/2" HSS tool bit that was long enough to reach the rod journal without the compound running into any of the twirling hardware.  Since my tool holder is set-up for 3/8" tools, I modified the bit by grinding the cutting edge lower by 1/8"so it was on center.  I then ground it to about 0.100" wide and gave it a round cutting end.  This worked reasonably well as long as I only took 0.010" cuts.  Any more than that and it would chatter.

Setup reversed for the second rod journal.

This shows the offset.
I turned the journal to size (1.000" X 0.750" wide) then used 400 grit emery paper to take off 0.0005" and smooth-up the bearing surface.  After the rods are done, I'll use lapping compound to seat the rod bearings.  Since the mains are non-adjustable bushings, I'm not able to lap them.

Tomorrow, I should be finishing the crankshaft.
28 January 2012:
Well, the crankshaft is done.  On this throw, I tried something I've tried before to minimize the chatter.

Turning the second throw.

The finished crankshaft.
What I did to fix the chatter problem was to wrap the crankshaft with a length of lead solder.  Since lead is a very highly dampened metal, it absorbs the vibrations.  The fact that it added mass to the workpiece only helped.

I put it up in the mill and cut the 1/4" keyways.  At this time, there's nothing planned for the power takeoff end of the crankshaft opposite the flywheel but I cut a keyway there, too.  No telling just what kind of work I might put it to doing.
29 January 2012:
Except for the bronze bushings (which I forgot to order earlier), the rods are about done.

The rod blanks and drawing.

Boring the big ends.

Rods semi-finished.
The rods weren't really complicated to do and the pickiest part of the job will be cutting the caps off with the bushings in place and milling the sawed surfaces flat and to dimension.  A shim pack will be made-up to compensate for the saw kerf plus cleanup.  After that is done, the rods will again be put in the mill and the big end bearing will be bored for a tight fit to the crankshaft. The finishing touch will be using "Timesaver" lapping compound to fit the rod bearings to the crankpins.

I've also drilled and tapped the 1/4-28 rod bolt holes before cutting the caps off.  This is to ensure the caps will register with the rods when assembled.  All I had to remember was to drill the 1/4" clearance hole only slightly past the pre-marked parting line.  The tap drill was run the rest of the way through the rods.   I've also drilled across a the bolts for a 0.050" safety wire to make sure that the bolts don't work loose.

The wrist pin bushings will be pressed-in last then the oil holes will be drilled.  A little metal will need to be removed from the pin bushings to get a good fit.

You will note in the center photo above, that I've lightly pressed a 0.500" dowel pin through both small ends.  This ensures that the rods will stay in registration during the boring of the big ends.
30 January 2012:
The rocker arms/cam followers are coming along.

The rocker arms, nearly ready to be assembled.
The most tedious part of the rocker arms was the slots for the cam follower ball bearings to fit into.  The slots are 0.200" wide, 0.750 long and are 0.400" deep.  Using a carbide 1/8" milling cutter, I had to make a whole mess of passes to get the slots made.  Finishing the rockers should be pretty easy, assembly only.
31 January 2012:
The follower/rocker arms are done.

Finished follower/rockers.
The view of the follower/rockers is looking toward the head.  The cams run on the rollers.  The tappets for the exhaust valves are opposite the rollers and the tappets for the intake valves are on the ends below the shaft.  The long tails are for the governor latch to work against.
2 February 2012:In response to a couple of requests, I'm belatedly posting a couple of scans of Hart-Parr documentation to try to explain the valve arrangement of the engine.

Cutaway views of the Hart-Parr 30-60 engine.
Basically, the engine is overhead cam.  The cam works directly on the single rocker arm for each cylinder.  On the high part of the cam profile, the exhaust valve is pushed open.  The rocker arm has a relatively strong torsional "hairpin" spring that tries to force the rocker to the intake profile of the cam.  The intake valve spring is weaker than the hairpin spring so, when the cam profile goes to the intake portion, the hairspring overpowers the intake valve spring to allow the valve to open.

To complicate matters, in the H-P engine, both valve springs are flat leaf springs with a third long spring, pivoted in the middle that operates against both valves.  This extra spring serves to increase the holding force of one valve when the other is open.

It's sort of complicated sounding but works on the tractors.  Now, whether or not I go with the actual three leaf spring plus hairpin spring or not is still in question.  There's plenty of room on the head for any number of arrangements and, if at all possible, I'd like to go with the H-P spring idea.

This seems like a pretty good breaking point so i'm probably going to take a few days off the project to catch-up on some other stuff.  Stay tuned.
7 February 2012:
In the last few days, I've gotten the rods done and pistons hung as well as a good start on the cam stands.

Rod marked for cutting.

Bushing being marked for cutting.

Bushing and rod cut.

Measuring for shims.

Checking diameter after shimming.

Boring bearing round and to size.

Rod and journal after lapping.

Wrist pin bushings and oil holes in rods.

Pistons hung on rods.
The procedure I use for cutting the rods and bearings and fitting them consists of measuring to the center of the big end bore then scribing the cut line.  The bearing is marked using a center square and is cut in two then witness marked to the rod.  The cap and rod joint and the bearing joint are filed more or less flat.  A little more is taken from the rod and cap in order to assure the bearing will be crushed in the rod when the bolts are tight.

The rod and bearing are assembled and the diameter is measured perpendicular to the cap/rod joint.  This determines the thickness needed for the shim pack in order to make the bearing more or less round and slightly smaller than the crankpin.  The rod is then assembled with the bearing and shims and the dimension is checked to make sure it's close.  At this point, the big end of the rod is carefully centered in the mill and the bearing is bored about 0.0005" smaller than the journal.

The rod, shims and bearing are mounted to the rod with the bolts only tight enough to allow the rod to turn on the crank.  The rod/crank are mounted in the lathe and lapping compound is applied.  Rotating the crankshaft with the lathe while holding onto the rod and occasionally tightening the bolts removes just enough metal to assure that the rod bearing and crankshaft are a good fit.  After disassembling, cleaning off the lapping compound and reassembling, the fit is checked.

The wrist pin bushings are pressed into the little ends of the rods and are reamed to fit the 0.375" wrist pins.  Then the pistons are assembled to the rods by pressing the pins through the skirts. With the rings installed, the piston/rod assemblies are done.  Note that I'm only using two rings (one compression and one oil control).  If there are blowby problems, I can always install a second compression ring in the empty groove.

Cutting out cam stands.

Partially finished cam stands.
The cam stands were cut to approximate shape from 1/4" steel plate using the bandsaw.  The rocker shaft and cam bearing bores were done.  Left to do is drilling the governor latch rod holes then pressing the bearing blocks into the stands then welding the stands to the mounting plates.
8 February 2012:
The valve train is beginning to come together.

Cam, rocker arms, latch shaft and speed adjuster in place to check fit.
Everything went fine until I got out the wire welder to attach the camstands to the bases.  DRAT!  The last time I used the welder, I forgot and left the tank turned on.  Although it's not empty, I sure un-used about three fourths of it!  Then, when I went to do the welds, the welder wouldn't feed wire.  I took a look and found out that one of the flanges on the 10 lb. reel of wire I just got had broken loose and the wire was starting to fall off.  I rigged a temporary reel on the lathe and spooled all the wire off of the broken reel, fixed the reel then re-spooled the wire back.  That took about two hours.  Some not-so polite words were spoken during that time.

After getting the welding done, I pre-assembled the parts to check the fit.  I will have to make a few changes because I've decided to run the engine in the opposite direction from the original.  This is because I've already got the alternator mounted on the tractor and it needs to be turning clockwise facing it.  One of the changes is to remove some of the cam hubs so I can put them on the shaft the other way around.  I'll use small setscrews on the abbreviated hubs to get the timing set then drill and ream for taper pins.
9 February 2012:Today was one of those "fiddly" days.  Getting the valve springs figured out so they worked was a challenge and I'm not sure I have them to the point where they'll operate correctly.

Leaf springs and pivot.

Spring to be modified for rockers.

Rocker return spring.

Rocker return spring in position.
The leaf springs are made from a piece of steel strapping.  I think they're going to be springy enough to do the job.  They are pivoted at a point that makes the exhaust side stronger than the intake side.  With both valves closed, the springs just have enough force to hold the valves shut.  Because of the pivot, when the exhaust valves are open, the intake valve springs are stronger and the same goes for when the intake valves are open.  This also applies increased closing force to the intake valves when thecylinders are latched-up and coasting.
Both valves closed.

Exhaust valve open.

Intake valve open.
For the lack of a better term, I'll call the wire springs the "override" springs.  Their purpose is to supply enough force to overcome the intake valve spring force when the cam is at it's lowest point (intake).  Without these springs, a much more complicated cam and a second follower would be necessary in order for both valves to operate.  

The first override spring I've made is made from the pop-up spring taken from a dead lawn sprinkler head.  After straightening, it was bent so it hooks under the exhaust end extension of the rocker arm, bends around the rocker at the bearing then is anchored using a method I haven't exactly gotten worked out.  Although the spring works as desired, I'm thinking of modifying it so it doesn't look quite so "lumpy".  Also, I'm using a scribe as a temporary holding device and am considering simply using a piece of large wire that lays against the exhaust valve guides, held in place by the hooked ends of the springs.
11 February 2012:
I think I've got the override springs worked out.  

Valve arrangement about done.
I re-did the override springs and added a bar to hold the head ends of them.  I think this will work but I'm going to have to modify the holdback bar where the red mark is.  This is an interference point with one of the head bolts.  What Ipll probably do is to cut the bar and weld in a square piece of 1/4" stock, drilled for the head bolt.  This will actually be an advantage as it will keep the bar from moving around.

Next, I'm going to do the cylinder block, consisting of the two headers, the jacket and the liners.
12 February 2012:
The header blanks are sized and the crankcase end header is well along.


Cylinder bores for crankcase header.

How cylinder liners fit into header.
Because my mill isn't big enough, I have problems squaring-up pieces that are over about 5".  I used the flycutter to do two edges of each piece but I could not do the other two edges with the flycutter because I couldn't get the knee down far enough.  I did the other two edges of the head-end header in the mill vise using an end mill but ran out of travel as you can see in the photo.  That necessitated flipping the piece over and sneaking-up on the surface from doing the previous end of it.  The header ended-up being within +/- 0.004" of true all around.

The crankcase end header had to have it's other two edges squared-up after clamping it to the table.

I then removed the mill vise and clamped the crankcase-end header blank to the table, shimmed-up 1/4" from the table.  After squaring it up with the table, I located and spot drilled the through bolt holes.  There are other holes in the edge of the piece that I'll spot and drill later.  

I used a 1-3/4" hole saw to start the cylinder liner holes then used the boring head to bore them out to 2.250" diameter to accept the liners.  Next, I'll put the header in the drill press and finish the already spotted eight clearance holes and the six edge holes.  After that, I'll do the head-end header.

15 February 2012:
The cylinder block is now a cylinder block, not just parts.

Block parts laid together.

Block welded, cleanup progressing.
Per my usual welding skills, I'm milling, filing and generally hiding the welding boogers.  I still have some cleanup to do then I have to tap the headbolt holes (10-32) and mill the deck flat.  I probably won't do any milling on the other end header unless it's warped in such a way as to make the alignment poor.

And, yes.  After welding, the liners still fit, although a bit tighter, which is good.
17 February 2012:
Since I'm getting tired of fighting surface rust on all the unpainted steel and iron in my engines, I'm changing my policy and painting the block/crankcase and maybe the head.  Of course, I'll use the official Hoyt-Clagwell company color, Rustoleum dark Hunter Green.

Today, I got the side plates finished and the top and back plates sized.

Side plates stacked together and marked.

Side plates and bearing clamps finished.
I goofed a little in finishing the bores for the main bearing blocks.  They are a slip fit.  I intended them to be almost a press fit.  I don't think that will be a problem though.  If I need to, I can always use thread locking Loctite to keep them from moving around in the 0.0005" clearance.  The clamping pieces are made of 0.625" bar stock with a step to hold the bearing blocks against the side plates.

All that's left to do is to drill and tap the holes in the side, top, bottom and back plates, install the crankshaft and set the end clearance and install the liners, pistons, head and work out the timing chain tensioner, the ignition and the mixer.  After that, I can tackle the flywheel which promises to be challenging.  The end is in sight.
19 February 2012:I've got the crankcase and base far enough along to be able to "stick' them together to check alignment and fit.

Bottom of bottom plate showing milled mounting surfaces and nut/shims.

Top of bottom plate, flycut flat.
The bottom plate, which is 1/2" thick, was sheared from stock by the outfit I bought it from.  Their shear must have either been out of adjustment or very, very dull.  The piece was more "chomped" off than sheared.  Aside from having a couple of really nasty cut edges, the plate was bent in the process.  I spent a while with the press, trying to straighten it and got about half of the bend out of it but ended up putting the plate in the mill and milling four "pads" of equal depth.  As you can see, the upper left pad just barely cleaned-up.

I then used 1/2-13 nuts to make equal height shims to mount the engine.  Flipping the plate over and using the shims to level it on the mill bed, it was then flycut flat for mounting of the engine frame parts.

Partial assembly to check fits.
I will have to mill the bottom surface edges of the cylinder block due to warpage from welding.  The amount is minimal, probably less than 0.015" will clean it up.

Note that I've only drilled and tapped one hole in the side and end plates.  This is so I can bolt it together to check fit.  The remaining clearance holes are drilled to the tap drill size and, after assembling the parts and getting the alignment correct, I will drill through the tap size clearance holes with a tap drill.  After drilling the tap holes, the clearance holes will be redrilled to clearance size.  This will assure everything stays aligned.  I'm not planning on welding this one together unless I notice that the parts are "working" when the engine has been run.  In that case, I will have to disassemble the engine, weld the frame together then strip and re-paint.  

Note that the cylinder block is the color the rest of the major parts of the engine will be.
24 February 2012:
After a pause, I'm back at it.  The rest of the frame hole threading is done and a starting crank has been made.

Starting crank in place.

Motoring to take stiffness out of main bearings.
The main bearings are a really close fit so I decided to motor the crankshaft for a few hours to insure against galling the journals when the engine is first run.  If the stiffness persists, I can always mix a little extra-fine TimeSaver brand lapping compound in oil and mineral spirits and apply the mixture to the oil holes.  Since TimeSaver lapping compound does not embed in the bearings or shaft and because it grinds itself finer and finer as it works, it's good for bearing fitting.  Per the instructions, it doesn't even need to be cleaned out of the bearing after lapping because oil flow will remove what's left of it.
25 February 2012:
The head gasket is made, the head is on and the pistons are in.

Motoring with head and pistons installed.

Relief for bore clearance on rods.
There was interference between the cylinders and the rods.  I had the sneaking suspicion that this would be the case but all it took was milling about 0.070" off the rods.  I made the oil scoops and they are on.

Everything seems to fit pretty well and I intend to motor it for a couple of hours to start seating the rings and bearings.  Once I get the top-end assembled and the timing chain and tensioner on and timed, I can see if the valves are sealing well.
26 February 2012:
Wow!  It's starting to look like an engine!

Motoring with head, cam, etc. working.

Check to see if oil is moving.  It is!
It took a bit of wrestling to get the cam, rockers, timing chain, tensioner, etc. done.  The cam timing's set to about optimum with the exhaust opening a little before BDC and the "overlap" (where the exhaust closes and intake opens).  The dang thing's looking like an engine now.

The timing chain tension idler is made of three pieces of some kind of self-lubricating nylon made into a flanged roller.  It runs on a brass shaft that has the mounting bolt drilled off-center to provide for adjustment.  Since it doesn't have a flywheel, I can't put the plugs in because if I stick my finger in a plug hole, the compression will cause the drive belt to slip.  In any case, it's throwing a lot of oil out the plug holes and exhaust ports so I know the cylinders are oiling.  I ran it with what I think is the proper amount of oil in the crankcase and it's getting everything nicely sloppy when motoring at about 550 RPM.

The governor action is almost non-existent at 550 RPM.  It just slowly comes out with almost no force.  I'm hoping it will respond better when the engine's running at what I think will be a good speed, about 750-800 RPM.

I'll be taking about a week off from the project and will restart sometime after the first week of March.
6 March 2012:
After a pause, I've gotten back to the project.  Today, I made the "distributor".

The "distributor".
The ignition is "distributed" using a 2-cylinder coil and grounding the plug that is not to fire.  It sounds kinda odd but I did the same thing with the Edwards ignition and it works fine.

There is a Hall-Effect transistor mounted on the phenolic piece with the handle.  This is the "fixed' portion of the system, which is rotatable through about 25 degrees of crankshaft rotation to allow for timing adjustments.  The white circular object is the rotor, which is made out of a piece of copper-clad 1/16" thick fiberglass printed circuit material.  The rotor has two magnets glued to it, separated by 90 degrees which pass the Hall Effect transistor to trigger the coil.  The rotor also has copper foil to ground the "unfiring" plug.  You can see the copper cladding through the rotor.

The coil/plug leads are located on the "fixed" part, one at six o'clock and the other at 9 o'clock.  
The rotor turns counterclockwise as seen.  One end of the coil secondary goes to the 9 o'clock lug and to the number one spark plug.  The other secondary lead the coil goes to the 6 o'clock lug and on to the number two spark plug.   When #1 fires, #2 is grounded through the screw and the foil on the rotor.  The #1 screw is located over the insulated part of the rotor.  The opposite occurs when the rotor has turned to the #2 position.

Scientific, what?
7 March 2012:I set the ignition in time and discovered that I had to move the #2 cylinder magnet in order to have both cylinders fire at the same point  in their cycles.  

Rotor with adjustable #2 magnet.
This was done by gluing the magnets to screws.  The #1 magnet was fixed in place.  I filed a slot for the #2 magnet so I could change the angle in relation to the #1 magnet.  This resulted in both cylinders firing within a degree or two of each other.

Governor latch follower and rod in place.
The next order of business was to make the governor latch follower.  In the photo above, you can see the roller (a small ball bearing), it's mount, the guide rod and the latch rod (the long one).

Inside the adjustment nut on the right end of the latch rod is a spring which works against the governor to set the engine latch-out speed.  Turning the screw toward the governor raises the speed and turning it away lowers the speed.

I may have to re-visit the governor when I get the engine running because I don't think it will make enough force at the speeds I intend to run the engine.  If need be, I will disassemble the whole camshaft and governor assembly and make some additional weight plates to attach to the present weights.

12 March 2012:
Not much has been done for the last week or so.  I came down with the Redneck Riviera Crud and haven't been spending a lot of time in the shop.  About all I've gotten done since the last entry is to make the governor latches.

Governor rocker latches in place.
In the photo above, the roller on the left of the cross shaft contacts the governor sleeve.  When the engine speeds-up the sleeve will move to the right as seen in the photo.  That motion will cause first, the left-hand latch to ride over the end of the rocker of the #1 cylinder when the exhaust valve is open.  The latch on the right is adjusted to hook the rocker of #2 slightly later so, if the engine speed is great enough, both valves will be latched open.  The setup for this test will have to be changed once the governor is modified and everything is re-assembled.

I hope to be able to give enough time to the engine within the next week or so.  Thanks for your patience!
14 March 2012:
I felt pretty good today so went out to the shop and actually got something done.  I'm pretty well along with the added weights for the governor.

Milling shaft slots in governor hub.

One original weight in place.

One extra weight in place.
The final plan was to add the weight to the other side of the sprocket/governor instead of trying to put the extra weights on the side with the originals.  I figured that I could get more weight on the other side.  More is better, eh?  AND, if I need even more weight, I can replace the present extra weights without disassembling the cams, distributor, etc.

Original weight on left.  Added weight on right.

Two of four extra weights added.
Adding weight to the governor will do two things.  First, it will allow it to be effective at lower speeds and it will increase the force of the governor.
20 March 2012:
After a "pause", I'm starting back with it.  The governor's reassembled and the camshaft and all are re-assembled.

All back together.
Now that I've got it back together, I find that we have a problem with the latching arrangement.  Since I've never been able to get up close and personal with a real 30-60, I have to guess what some of the mechanisms look like.  In operation (at present) all's well until after the first cylinder (on the left) latches and the second cylinder (on the right) latches.  Then, since both exhaust valves will never be open at the same time, the cam will never be able to relieve the pressure of both of the rockers against the latches at the same time.  This will keep thge latch rod from moving to the left and the engine will stay latched-up.

I think I've got a fix for this condition and that's to put a swinging element on the #1 latch so, when the engine speed reduces from both cylinders being latched-out, the swing element will keep the pressure of engagement from the #1 rocker from keeping the latch from moving away.  As soon as the second (right-hand cylinder) unlatches, the left-hand cylinder latch is free to move when its' cam is in the exhaust position.  Easier to do than explain, I'll photograph my "fix" as I make it.

Just for the heck of it, I may motor the engine to see if I may be wrong and the swinging element isn't needed.
21 March 2012:
Today was a bust!  I belted-up the engine to check out the governor operation and found the design to be a failure because of the orientation of the weights and cam surfaces.  There is just too much binding in the whole system.  Because of that, I've scrapped that idea and will design a flyball governor that is belt driven from the power take-off side of the crankshaft.  I plan to run it at about twice crankshaft speed (as opposed to half crankshaft speed per the other design).

Sometimes things work out and sometimes you need to just back-off and start over.  This is one case.  A minor setback.

I've also been thinking of the procedure for machining the flywheel and have decided to go ahead and get the spokes cut using water jet.  I can do the turning all right but the spokes would require a LOT of machine time and many setups - that process is just too prone to a major "Aw-Shoot!".
24 March 2012:
I've re-designed the governor to a standard flyball type.

The new governor.
Note that I haven't removed any hidden lines.  This makes the drawing a little harder to read but I think you can figure out what I've got in mind.

The governor will be belt driven from the side ooopsite the flywheel using a 1/4" round leather belt.  Both positions of the governor are shown.

With the engine at rest, the weights are against the shaft and the shafts and linkage are as shown.  When the engine speeds-up, the weights move out.  Since the lower ends of the links is vertically fixed, the top end of the links moves down.  The shaft goes through the drive-shaft and to the "cup" and thrust bearing.  When the shaft moves down, the linkage is pulled down, rotating
the latch shaft clockwise and causes the latches to engage the rocker arms, holding the exhaust valves open.

Speed is adjusted by turning the vertical bolt that changes the spring pressure holding the shaft up.
25 March 2012:I've got a good start on the new governor.

The mainshaft and pushrod.
After thinking about it, I was a bit reluctant to drill and ream a 1/4" hole through the mainshaft.  Without perfect drill bit geometry, there's no telling where the hole will end-up after going over 5 inches.  Taking a peek in my pipe bin, I found a piece of schedule 80 (thick wall) 1/8 pipe.  The I.D. was too small but it could easily be reamed out.  The O.D. was also too small by about 0.100" but that could be remedied with a couple of bushings.

After reaming out the pipe, the fit to the 1/4" pushrod was too snug so I lapped it to fit.  And a nice fit it is!

The governor so far.
The frame for the governor is made of 1/4" steel plate with a couple of 3/8" hunks for the bearing mounts.  At the left (in the photo above)| you can see the speed adjust bolt.  This will change the spring pressure working against the pushrod to vary the engine speed.

The bearings are on order as well as a length of 1/4" round leather belting and some clips.  They should be here on Tuesday, just in time.
26 March 2012:
Moving right along.

Governor as of today.
It doesn't look like much has been done but I got the lower spring mount, the upper spring mount/thrust bearing, the pulleys and the mounting holes finished. All that's left to do is the weights (2 each), the weight arms (8 each, waiting for the metal) with bushings, the linkage to the latch shaft (waiting for metal), the bearings (2 each, waiting), the drive belt (waiting) and some fiddly bits.  Ever onward!
27 March 2012:
Well, the parts came yesterday (a day early) after I'd posted progress to date.  Today, I made significant progress.

Making the weight arms.

Finished weight arms.
In order for the weight arms and the weights to line-up properly, the 1/8" thick arms had to be milled to 1/16" at one end so they could overlap.  I've decided to not bother with making the 1/4" bushings for the weight arms and simply drilled the arms for clearance of 8-32 machine screws.

Governor and linkaga minus weights and weight arms.
I also got the governor bearings installed and assembled the governor minus the weights and weight arms.  There is a 1/2" diameter barstock link to align the arms from the latch shaft and the governor.  I applied something I saw on my '50 Chevrolet front suspension.  On the knuckles and upper and lower arms, GM for years simply threaded the arms and made nuts that fit into the "A" frames.  As long as you kept them greased, they did fine.  In the right-hand photo, on the latch arm end of the link, I threaded the link and the arm 8-32 then tightened a brass screw into the arm.  The link was then screwed onto the screw, leaving it about a quarter turn loose.  The governor arm was then screwed tightly to the link.  The motion is smooth.

Tomorrow, I'll make the weights and assemble the rest of the governor.
28 March 2012:
The only thing left to do is to work out the valve latches.  I'll take a couple of days to think this one out while doing some "honeydo" projects.

Governor with engine at rest.

Governor with engine at 450 RPM.
A visit to my friendly local hardware store could be in order.  In all my boxes of springs, I can find none that allow the governor to operate at somewhere around 500-600 RPM.  I have the one shown that maxes out the governor at somewhere over 450 RPM and another one that just gets the governor off rest at about 600 RPM.  This governor will be plenty powerful to operate the latches so I'm pleased with it.

The other alternative is to re-make the pulley on the governor so it runs a little slower.  It's presently running at about 1-1/2 times crankshaft speed.  Within the space I've got, I can most likely get the ratio down to about  1-1/4 times crank speed.  This would probably make the spring that's on it now work all right at about 500-550 RPM.  As I say, I've gotta think on it.
31 March 2012:
Got me some new springs and found a pair that will work.  One of them is on the rotating part of the governor below the top swivel
(you can see it in the left-hand photo below) and the other one is in the normal place.  The top spring compensates for the weight of the assembly at rest and the bottom spring adjusts for speed.

Below governed speed.

At #1 (farthest) latchout speed.

At #2 (nearest) latchout speed.
I dunno if you can see how the latches operate in the photos.  The latch for #1 cylinder (farthest away in photos) has a hinged plate on it.  This is to allow the governor to unlatch the #2 cylinder (nearest in photos).  Because, when both latches are engaged, and since there's always pressure on one or the other of them, the friction between the latch tips and the rockers is enough to keep either of them from moving toward the unlatched position.  The little plate allows the governor shaft to rotate enough to release the #2 latch when the speed is reduced.  It took a bit of fiddling to get it to work right but I think it'll do until I get the engine running and am down to the "fiddly bits" of tweaking it to run well.

While motoring it, I've noticed that it's throwing a lot of oil out of the ports and spark plug holes.  I hope this isn't a hint that this might be a smoky beast.  It seems to me that, when the flywheel is done and I can run it with the plugs in, compression should tend to shove the oil back toward the crankcase.
1 April 2012:
Today was one of those "two steps forward, one step back" days.   The step back was when I was motoring the engine while working on the mixer and exhaust, when I heard a snap.  I took a look and found that half of one of the "hairpin" springs had broken off.  Since the intake valve was still opening all right, I decided to leave it that way and, if it continued to work all right, I'd just cut off one end of the other spring.  Shortly afterward, though, while motoring, I heard another snap.  The other end of the spring had broken off and the intake valve wasn't opening.  Gotta re-think that one.

At least the exhaust stubs are done and I've got a start on the mixer.

Temporary exhaust stacks.

Beginnings of the mixer.
The exhaust stacks are some 3/4" EMT tubing I had around.  The mixer, since it will be located below the gas tank, will have a float chamber.  The aluminum float chamber is part of a scrapped "aw-shoot" piston.  I plan to make the float out of 0.0015" thick brass shim stock.  The brass tube above the float chamber will go through the float and will guide the float by fitting over the stud mounted on the drain plug.  On the upper part of the tube, I'll use a viton-tipped float valve off of something.

I'm going to bore out the throat of the mixer to somewhere over 0.500" which is the size of the port.  I will then press in an insert with an I.D. of about 3/8" to act as a venturi.  Necessarily, the fuel mixture needle valve will be somewhat hard to access because of the shallow height of the cylinder block.  If it poses a problem, I'll make a flexible shaft to bring the adjustment wheel to an easier access point.

Yet to figure out is how to mount the float chamber to the throat and get the fuel to the jet.  It'll probably include drilling vertically down the 1/4" thickness of the float chamber wall then intersecting this hole with another horizontal hole close to the bottom of the float bowl.  At about the level of the fuel or slightly higher, another intersecting hole will be drilled that will go to the jet.  The top of the vertical passage will be tapped and a screw will be bottomed-out in short threads to seal it.  I think I can manage mounting the float chamber by using the horizontal holes.  We'll see.
3 April 2012:
Another one of those good and bad days.  I thought I was finished with the mixer but the float valve doesn't want to work.

Fuel passage detail.

Parts of the mixer.

In the left-hand photo, you can see at the bottom of the float, the screw that connects it to the mixer throat.  Right above that is a hole that goes through the float chamber.  This hole intersects with a vertical passage from the top of the chamber and through the venturi hole.  The outside of the lower hole through the chamber is sealed by the gasket that goes between the float chamber and the mixer throat.  The top of the vertical passage is partially tapped 4-40 and a small setscrew is screwed tight into the incomplete threads to seal it.

I haven't necked down the throat but have used the horizontal lead from the float chamber fuel passage to make a sort-of venturi.  This is a 1/4" thick steel bar, drilled 0.150" at a right angle, roughly centered in the mixer throat.  The venturi is drilled and tapped 10-32 for the needle valve to the perpendicular hole, then 0.040" from the other side of the perpendicular hole to the fuel passage.  The needle valve seats into the 0.040" hole.

I think I'm going to have to make a new float that floats better.  This one does float but won't push the valve closed enough to not leak.

I've ordered new torsion springs to replace the "hairpin" springs that have failed.  I took a guess at what torque the springs need to produce and will see, probably tomorrow.  I also ordered a governor spring that has about twice the compression pressure as the ones I've tried before.  I'll remove the spring I put between the top weight arm and the shaft because I think that is contributing to a sort of oscillation.
7 April 2012:
The new float is done using as raw material, cork lab stoppers.

Raw material for float.

Grinding to size.

Drilling for needle/guide.
After thinkin' on it for a while, I decided to get some cork and make the float out of it.  The material that seems to be right is simply........corks.  The problem of how to accurately and neatly shape the cork into a float was done by using the Dremel in the lathe as a little-bitty toolpost grinder.  It was kind of messy but got the job done.  Before cutting the float off of the workpiece, a hole was drilled for a snug fit of the needle/guide.

Grinding needle.

Finished float.
The needle was made from a piece of small drill rod.  The point was made with the Dremel toolpost grinder.  After finishing the float and checking for fit, I dug out some clear epoxy I got at a swap meet and mixed-up enough to test against gasoline.  A piece of PC board material was coated with the epoxy and, after using the heat gun to accelarate the hardening process, it was dipped into gasoline.  After an hour there was no softening of the epoxy so I deemed it fit for the float.  It's probably going to take 24 hours or so for it to cure enough for me to assemble the mixer and test the float valve.

Replacements for "hairpin" springs.

New springs in place.
Another thing I'd ordered was a couple of hefty torsion springs to replace the home-made "hairpin" springs.  These are made of 0.125" diameter music wire. After trimminmg the ends of the springs, the rocker arm shaft had to be disassembled to install them.  I like the way they work and, since they are barely stressed at all, they should work fine.

The flywheel blank goes to the machine shop for the waterjet cutting on Monday.  The wheel will be in the shop for up to a week so I'll work on the mounting, cooling, etc.  The plan is to remove the McVickerish engine from the 2009-1/2 Algore Edition Hybrid Hoyt-Clagwell and replace it with the 30-60.  The base plate of the new engine has the mounting holes drilled for the chassis of the tractor but, since the plate is shorter than the plate on the McVickerish, I'll have to drill a couple of new holes.  The alternator on the tractor will drive off of the flywheel, the same as with the McVickerish.

8 April 2012:
The mixer's finished.

Mixer (upside down) with choke closed.

Mixer (upside down) with choke open.

Mixer in place for test fit.

The epoxy hardened nicely despite it's age.  The test strip soaked in gasoline overnight and was not affected so I think we're ready to go.  I assembled the mixer and made a choke for it.  I haven't tried hooking up the fuel line to check operation of the float because I want to allow a few days for the epoxy to fully cure.

In the next part, I will finish the engine, get it mounted and see if it will run.


Go To Part Two
Mounting The Engine, Making The Flywheel And The Fiddly Bits.


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Boy!  This is fun!!!

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