Brian....sorry for the delay...have been out of town for last 5 days. I used just a piece of 1/4" dia craytex (rubberized abrasive) extended from a collet in the mill and dressed it several times during the process.
A short update to the work on the pump over the last day or so, some bling, which is uncharacteristic for me, and I received yesterday the globe valves from PMR, one of which will be for the priming cup which I still have to make. A few pictures follow
Here is an initial video of the engine under power. It not finished yet but the final plumbing and valve work can be done while I am painting the rest of it.
Charlie, you may have seen already some of the hoglet and webster build logs which may be a starting point. Not sure they are true beginner models but depending on skill levels and experience, probably doable. There are far more experienced IC guys here that I hope will offer further and no...
Welcome Zane, and thanks for the introduction. Hopefully some of the members more into multi-cylinder small IC engines will be able to help with your question. Some pictures of the "beast" might be helpful too.
Sorry to hear that...castings are not the easiest thing to begin on though. Start with something simple made from bar stock to build your skills and confidence up. Mistakes are less expensivie too!! Welcome to the forum by the way and when you can maybe post an introduction in the welcome...