My Flat Head Hit Miss Engine

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Joined
Apr 22, 2020
Messages
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Location
Weirsdale, Florida
(Brian Rupnow has a thread he started on a similar build and watching his thread is what gave me the idea for this engine. Even though the engine types are the same my engine will be very different in construction and appearance. I want everyone to understand I don't want to take anything away from Brian or his design this is just another way to look at it.)



The withdrawal pains have gotten to be too much for me I just have to start another engine project. This one will be a flat head hit miss engine. Evidently flat head engines come in several different types and many different names. To me a flat head engine has the intake and exhaust valves in the engine block like a Briggs and Stratton or an early Ford V8 so that will be the type I will build.
1" piston
2" stroke
Ball type governor
Horizontal style

I make very few drawings, you can't even call them drawings more like layout scribbles. I am never sure just what the project will look like when it is finished. I will make an assembly like a cylinder block and then everything else is fitted around that. The next component is built and the rest of the parts fit around that and so on. This can lead to some interesting problems later but that is the fun of it.

I started with a piece of cast iron about 4" long and bored it for a 1" piston.
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Next was a block of aluminum 4" X 3.5" X 3" that I bored to fit the liner.
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And here they are for a test fit.
Note the rectangle marked in the top of the block.
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Next to cut the water cooling area.
There was a lot of swarf from this.
IMG_1280.JPG
And the finished water jacket with the liner slipped in.
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The thicker side of the block is where the valve will go so that needs to be milled 3/4" deep.
I made the cavity extra deep and long to be sure to have plenty of room for for the valves.
IMG_1286.JPG
This picture shows the valve box and the two holes in the front of the block are for the valve guides.
Note that the one hole has a matching hole in the opposite end of the block. This hole is for the exhaust valve lifter. The intake valve is atmospheric and is opened by vacuum.
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I drilled and taped the holes for the cylinder head and gave it a good cleaning.
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The liner was permanently installed with a liberal amount of lock tight.
IMG_1292.JPG

The next step will be to deck the cylinder head end of the block to insure the liner and block are the same height but not until the the lock tight has set up.

Ray
 
As I said before I seldom make any drawings but this cylinder head is different from anything I have made before. All of my other cylinder heads were round. Simple to layout the head bolts in a bolt circle for the head and the block but this one is rectangular. I drew this up in Aspire and included cutting the head gasket as well.

I cut the head gaskets first and boy am I glad I did. Somehow I got the gasket size 0.080 too short and 6 of the head bolt locations off as well.
I haven't found just where I went wrong but I redid everything and now it is right. My only loss was 1 head gasket so not so bad.
This is the way I cut my gaskets using a drag knife so I made several on my vacuum table.
IMG_1297.JPG
Fits good.
IMG_1298.JPG
I mounted a piece of 0.625 aluminum plate with a spoil board under it and milled out the combustion chamber. I made the chamber 0.200 deep but I am not sure that is right. I am shooting for a 5.5 to 1 compression ratio so it should be close. If it is too deep I can shave some off the head to raise it.
IMG_1300.JPG
I then flipped the piece over and milled the top side of the head and cut it out.
IMG_1302.JPG

Top done
IMG_1305.JPG
Bottom side
IMG_1306.JPG

It turned out just right after all.
All the bolt holes even lined up.
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I put it up on a pedestal for show.

Ray
 
Today was valve day and all went well
I made two valve guides, two 5/16" valves, two valve spring keepers and one light intake valve spring.
IMG_1312.JPG

Assembled
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I will lap the valves before I install the valve guides it will be easier that way.
I can still do more laping later with the guides installed if needed.

Ray
 
Did some laping on the valves and then installed the valve guides.
I drilled and taped the holes for the intake and exhaust ports.
I spent some time doing some cosmetic features on the cylinder block.
It makes it look more professional what do you think?
IMG_1316.JPG


I also got a good start on the crank shaft but still a lot left to do.
Note the sealed ball bearing for the connecting rod end.
IMG_1318.JPG


Ray
 
A short day today but it turned out fine.
I reduced the webs on the crankshaft and rough cut the shafts.
Also installed #2-0 taper pins on the connecting rod end of the crank. These were driven home with a liberal amount of loctite.
IMG_1320.JPG

Tomorrow I will cut them off and file them smooth.

Ray
 
I had trouble sleeping last night so I went out to the shop early this morning. (It happens when you get old)


Finished up the crankshaft and painted it.
I cut out the side rails and the bearing caps.
IMG_1325.JPG

I think it is time for a nap.
Ray
 
Well today I bolted the bearing caps on to the side rails and bored both rails for the crankshaft bearings.
IMG_1326.JPG


It turned out so well I decided to layout the holes for the side rails and cylinder block in a piece of 0.375 aluminum plate. The plate will be the main frame that holds everything together.
There are 18 #6-32 bolts that secure all the pieces together and this is where I usually run into some kind of trouble. Marking, drilling, counter boring, and taping this many precise locations usually causes me to wallow out the holes to make it fit. Not today only one hole was off by about 0.010 and I was able to shift things around and make it work.
A few pictures
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Ray
 
I thought I would have a short day today so I cut out the cam for the engine.
CNC makes it so easy.
IMG_1338.JPG

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And then why not cut out a flywheel slug. It shouldn't take too long.
I bought a chunk of cast iron on E-Bay at a good price to make the flywheels out of. It was advertised to be 6 1/2" in diameter and 3" long. Well it was over 7" in diameter and that may seem to be an even better deal but not for my band saw.
IMG_1344.JPG

It is kind of hard to see from the picture but the blade roller on top hits the part and stops the cut before it half way through the bar. That leaves about 1 1/2" in the middle uncut. I was able to find a hack saw with a deep enough throat to reach over half way to finish the job. Total time to cut one slug was 2 1/2 hours and a sore arm. I may just put the remaining part in the lathe and make the OD smaller so my band saw can cut all the way through for the next one.

Ray
 
It is kind of hard to see from the picture but the blade roller on top hits the part and stops the cut before it half way through the bar. That leaves about 1 1/2" in the middle uncut. I was able to find a hack saw with a deep enough throat to reach over half way to finish the job. Total time to cut one slug was 2 1/2 hours and a sore arm. I may just put the remaining part in the lathe and make the OD smaller so my band saw can cut all the way through for the next one.

Ray
If you had a sawzall around one of the long blades would do the trick with a lot less wear and tear on the arm.

Engine is looking great ! Very nice work.
 
A suggestion that eased the right arm fatigue for me. I bought a cheap (£35) branch saw, 2Ah 12V battery, for pruning bushes. I bought the hacksaw 22 tpi blade for it and it cuts through large sections slowly, but taking it easy and letting the blade do the work, no pressure needed, just patience, and it has cut some large lumps of metal for me. It is now beyond repair, as it was not built for all the work I did with it. (10 in dia. Monkey puzzle tree , 10 in walnut tree branches, 2 x 6 in. Dia holly trees, etc. felled amongst other jobs). I made a new steel crank for the drive, changed circlips retention for crank, etc. But all the cast soft metal bits are too worn to bother with more repairs. But I may buy another when in stock, as it is a beautiful tool to use. Saves so much muscle!
K2
 
Thank you both for your suggestions but I will cut the slug down in diameter closer to my 6" goal and then split it in half on the band saw. I will then have two 6" pieces for the flywheels and one 7" piece for later use.

I decided to polish the main frame and paint the cylinder and side frames Allis Chalmers orange.
IMG_1345.JPG

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Painting at this stage has a tendency to make me more careful and precise during the rest of the build.
I have other commitments for the rest of this week which will put a hold on this project.
Ray
 
Well today I bolted the bearing caps on to the side rails and bored both rails for the crankshaft bearings.
View attachment 144841


It turned out so well I decided to layout the holes for the side rails and cylinder block in a piece of 0.375 aluminum plate. The plate will be the main frame that holds everything together.
There are 18 #6-32 bolts that secure all the pieces together and this is where I usually run into some kind of trouble. Marking, drilling, counter boring, and taping this many precise locations usually causes me to wallow out the holes to make it fit. Not today only one hole was off by about 0.010 and I was able to shift things around and make it work.
A few pictures
View attachment 144842
View attachment 144843
View attachment 144844

Ray
This is looking very nice!
And not one mention of JB weld anywhere!
Looking forward to seeing it run.

Sid
 
Having never even owned or know what J B weld actually is, I can only guess it is epoxy resin adhesive?
It has it's place. I used some today, to fix some brackets to a phenolic resin circuit board, as a neater joint than tiny nuts and bolts. I didn't have any "resintrode" welding rods to hand....
The resin board was needed as aluminium or steel would have been incompatible with electricity and magnetic fields in the generator.
K2
 
The JB weld reference was because some builders use it instead of using a little care and precision in their work. ;):oops:
 
Having never even owned or know what J B weld actually is, I can only guess it is epoxy resin adhesive?
It has it's place. I used some today, to fix some brackets to a phenolic resin circuit board, as a neater joint than tiny nuts and bolts. I didn't have any "resintrode" welding rods to hand....
The resin board was needed as aluminium or steel would have been incompatible with electricity and magnetic fields in the generator.
K2
It's a brand of heat resistant epoxy with various fillers added. Pretty good stuff when used appropriately.

Being comparatively heat resistant, it can be used for non structural repairs on some engine parts. There are lots of videos on YouTube of people using it inappropriately, for example to repair broken connecting rods or to make pistons. Pretty funny, but the results are easy to predict.
 
It's also very good for fabricating model engine parts where it may be difficult to join pieces such as cast iron or where you don't want to risk distortion by welding or silver soldering the machined parts together. Also certainly helps if you want your model a bit more shapely and looking like it was from castings rather than a boxy barstock job.

And yes being that it is machinable can also be used to correct casting defects as well as machining errors both your own or ones on part finished projects that you may buy second hand.
 
In one job, back in the mid-70s an adhesive maker showed me an appication for 2 part Epoxy resin where it was used to fill small aluminium tubes that were the rungs of wire rope ladders used on Everest expeditions, mountain rescue work and in the Antarctic. The adhesive fixed the thin flexible wire rope to the aluminium tube rungs of the rope ladders. Of course, there was a lot of tooling to mix the 2 resins as the mixed resin was pumped into the aluminium tubes pre-treaded onto the wire rope. But the resin helped to stiffen the tubes from buckling as well as securing them to the wire rope.
K2
 
Back from my short trip and had some time to work on the project.

After I reduced the diameter of the cast iron chunk it was much easier to split it into two disks.
IMG_1349.JPG
After some cleanup at 6 1/4" in diameter.
IMG_1350.JPG

I reduced the web on both sides of the disks and bored the center hole with a 5 degree taper. I will be making taper locks for the crank shaft as I really like that design. No key ways, no set screws, and the flywheels can be moved in and out easily.
I even got them painted.
IMG_1352.JPG

After a lot of cast iron cleanup time I started on the timing gears. I made these gears for a project over a year ago but it ended up I didn't need them so they should work fine here.
The large gear has a steel bushing pressed into the bore and the cam lobe is pressed onto that.
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The other side has a pulley pressed onto the hub of the timing gear. This pulley will transmit power via a o-ring to the governor mounted above.
IMG_1357.JPG


Ray
 

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