Horizontal Air Cooled Engine

[Kim]

You can never have too many clamps! 

Kim

[crueby]

You can never have too many clamps! 

Kim

Absolutely not. I have a lot, and still had to borrow a bunch for this glue-up of a boat coaming lamination...

Sorry Brian, couldn't resist throwing that picture in. Watching along on your build as usual!
 

[Brian Rupnow]

WOW!!! I've never seen so many clamps together in one place. I have a lot of clamps, but nothing close to that.---Brian

[Brian Rupnow]

This morning I went down street and bought my ignition points and condenser. I machined an ignition cam and fitted it in between the sideplate and the flywheel on the side opposite from the timing gears. I flame hardened and quenched my cams in oil, and after clean up got them mounted on the camshaft. The con rod clears the cams when it rotates, by about a gnats hair. (That's about .001"-.003").

[Brian Rupnow]

And at the closing of the day---I have tappet guide bushings made and installed, and valve cages made and installed. Setting out by itself on the end of the engine baseplate, is one lonely valve cage that ended up being too short. I thought it looked too short when I made it (it was the first one) and after doing some checking I found that I had modelled it too short. Ahh poop!!!--Thats why, when you buy a set of drawings from me, the mistakes have already been found and corrected. My original plan was to make the rocker arms out of steel, but I found an offcut of brass that might work for me. I'll figure that one out tomorrow.

[Brian Rupnow]

One step forward, two steps back. I realized after loctiting the valve cages into the cylinder head that I hadn't put the counterbores in the cylinder head for the valve cage flanges to fit down into. I don't have a great deal of free room in the combustion chamber, so it's pretty important that the flange sets down into a counterbore. Sparky asked me about that, and I thought about it to the point where I pulled the valve cages out of the cylinder head before the Loctite had a chance to set up. What I really need is a 13/32" diameter reamer with no chamfer on the end, with the end drilled and tapped for a pilot. If I put a counterbore in, I have to do the main hole and the counterbore all in one set-up, otherwise I can never get the counterbore concentric with the main hole. After doing some frantic Googling, I find that there are reamers with pilots available, but the reamers all have a chamfer on the end. I need a reamer with no chamfer on the end and with the end drilled and tapped so I can put different size pilots on it. Does anyone know of a commercial source for such a thing? I do have a guy near Barrie who sharpens endmills and drills and can make a custom cutter for me, but he's not cheap.---Brian

[Jasonb]

Take a bit of drill rod turn to the required OD and drill and ream for your pilot. Cut a few teeth in the end (file will do) then harden.

This will be like a counterbor that can be used,

Though as there is little sealing going on around the edge you could just as easily use a 7/16" milling cutter

If you want to buy something then look up aircraft counterbores

[michaelr]

I used a similar method as Jason's for the internal facings for the main bearings on my Centaur engine, the cutter was made from mild steel with hand filed teeth and case hardened, fitted onto a hand driven mandrel using a ratchet Handel and Socket.
I,m sure you could use similar methods as these.

[Brian Rupnow]

  Yesterday I was chasing all over the internet trying to find what I wanted but had no luck.---I was calling it the wrong thing!!!  This morning I woke up realizing that I should have been searching for a "piloted counterbore". Ran downstairs and checked the internet again and found out that everybody and their dog is selling "piloted counterbores"!!! I started phoning around and then realized that this is Saturday and all the shops are closed. This is a tool I could make but would rather buy. ---Will find out more on Monday.---Brian

[Roger B]

I hope you have success with your counterbore hunt  In the picture with the contact breaker fitted there looks to be very little clearance between the terminal nuts and the end of the camshaft  Maybe it's just the camera angle 

[Brian Rupnow]

It's just the camera angle. I have enough clearance for what I need to do. Nothing big or fabulous machined today. Just a pair of brass rocker arms and axles and hardened 01 steel round contact pads on the end that touches the end of the valves.

[Brian Rupnow]

These two little guys that look like tubes are actually the tappets. They have a short counterbore in the end you can see and are solid at the other end where they rub against the cams. The counterbore which is about 0.350" deep holds the end of the pushrods for the valves. The cams have been flame hardened and quenched, and the tappets have also been flame hardened and quenched. They are made form 01 steel and quenched in old motor oil. Once the engine is fully assembled, you won't see these tappets anymore, as they are mostly contained in the tappet guides.

[Brian Rupnow]

At this point, I don't know exactly how long the pushrods are going to be. I can get a length from my 3D model, but in situations like this I just make the pushrods 1/2" longer than what the computer said and will trim them to length on finished assembly.

[Brian Rupnow]

This afternoon I finished all of the fan mechanical parts except the fan blade. The fan is represented by the disc of cardboard, 2 1/4" diameter.---I don't know why it isn't centered in the shroud, but I can move the hole in that brass strap enough to center the fan, and nobody'll know. There is a lot going on in that fan hub. There are two 3/16" diameter ball bearings in there that were originally intended for a router, and a spacer between them.---I like it.

[crueby]

Great progress Brian, hard to keep up!