Inverted Hit n Miss engine converting to IC

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These are pictures of an inverted hit n miss engine I completed almost a year ago.  The engine was designed and built to run on compressed air, and while it runs good, I decided it would be more fun and more exciting if it was converted over to internal combustion.

Inverted Hit n Miss engine converting to IC

Inverted Hit n Miss engine converting to IC

Inverted Hit n Miss engine converting to IC

Currently the engine has a bore and stroke of 1" x 1.5".  I plan to make a new cylinder with a bore of 1.25", leaving the stroke at 1.5".  I'll also make a new, thicker head and a shorter connecting rod to reduce the compression ratio to around 5:1.  New intake valve assembly, new exhaust valve assembly, simple needle valve fuel mixer, new cam, ignition, 10mm spark plug and few other odds and ends should do it.  Stay tuned...

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At the last minute, I decided to leave the bore size at 1".  I wasn't sure the crank disk and crankshaft could take the additional power from a 1.25" bore and I figured I might as well use as much of the existing engine as I could.

So here is the original cylinder sitting on the head.

Inverted Hit n Miss engine converting to IC

And here is a picture of the bottom of the head.  Socket head cap screws are used up from the bottom to hold the cylinder in place.  A socket threaded to accept the spark plug will be silver soldered into the center hole.  The spark plug will be on the bottom of the head and will not be visible.  I'm hoping I don't have fouling problems from this arrangement.

Inverted Hit n Miss engine converting to IC

Here is the head from the top, cylinder side.  I cut a deep recess in the middle to lower the compression ratio.  This should bring it down to 6:1 or so.  The recessed holes on the outside corners accept socket head cap screws which hold the cylinder/head assembly to the engine base.

Inverted Hit n Miss engine converting to IC

I got roped into helping SWMBO paint the spare bedroom so may not have any updates for a couple of days (1 day to paint and a second day to recuperate!)  :'(

Chuck

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Got some catching up to do.  I attempted to solder the spark plug spigot into the steel head and failed miserably.  I then made a new head out of brass, but in my hurry to get making chips, I didn't think it through and didn't leave enough meat on the head to attach the intake and exhaust valve assemblies.  So, I made yet another head out of aluminum.  Here are the results.

Inverted Hit n Miss engine converting to IC

More work done on the top.  The threaded hole coming in from the side will be the exhaust side.

Inverted Hit n Miss engine converting to IC

Another shot of the bottom after drilling some holes and shaping the sides.  The side with the long flat section will be the intake manifold side.

Inverted Hit n Miss engine converting to IC

And the top...

Inverted Hit n Miss engine converting to IC

Had to bore out the hole in the base to accommodate the larger circular portion on the bottom of the head.

Inverted Hit n Miss engine converting to IC

Here's the base with the head bolted in place.  I also had done a bit more shaping after I took the pictures above.  There is now a raised ring, 1/16" thick and 1/16" high that encircles the cylinder.

Inverted Hit n Miss engine converting to IC

And a picture of the base and head with the cylinder sitting in place.

Inverted Hit n Miss engine converting to IC

I also plan to fancy up the cylinder, do some kind of curvy profiling on it, but haven't decided on a design yet.

Chuck

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And another photo with the beginnings of the exhaust manifold and valve assembly.

Inverted Hit n Miss engine converting to IC

The exhaust valve and cage will bolt down on top of the piece in the picture.  

Chuck

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The only thing left on the Exhaust Assembly is the valve itself and retainer pieces.  Here's a few pictures of the assembly.

Inverted Hit n Miss engine converting to IC

Inverted Hit n Miss engine converting to IC

Inverted Hit n Miss engine converting to IC

Inverted Hit n Miss engine converting to IC

Think I'll tackle the intake assembly next, probably tomorrow.

Chuck