Thanks for all the encouragement! This engine has turned out to be a pretty complex animal. Today I bored out two cylinders and mocked up the cam shafts and manifolds. I will cut in the cooling fins after everything is bolted up tight.

I am going to make my own carburetor once she comes to life, but I am going to use a vapor carb to trouble shoot, so the intake manifold needs to flexible. I mocked up the 1/2'' square bar to see how this might work. I think I am going to do 2 carbs, but might do just one.

The cam supports will be cut out to as little as is needed to support the shafts and bearings.

The exhaust manifold will most likely be two separate pieces... maybe brass, maybe aluminum.

This pic gives you a bit of perspective on size. When two of them are mounted on the block it is going to be massive....

More to come...
Doug