The engine I'm contemplating using for this pusher is an OS 40FP. It currently has a single thrust washer between the drive hub and the case.

I thought I could just order a half dozen stock thrust washers--for the FP-- from TH at $1.89 apiece and start shimming.

Good point about the different expanding rates on the case and crank. I'll shim it a little loose and run it for 5 minutes then pull it down and check wear from the back-end.

'Course--I could just break down and buy a ball bearing engine for the rear engine. Slap the 40FP on the front and avoid any troubles.[:-]

That would probably be the smartest thing to do. Money is just kinda tight right now. I've been hurt and off work since March 25, 2005. Have had 2 surgeries on my lower back. The temporary dissability payments from the work comp. insurance carrier---are a bit skinny at only 66% of my usuall wage.

The kids gotta eat and the bills need to be paid before I can justify spending too much $$ on the toys for now. My finance officer (wife) is keeping me on a tight leash right now. Darn financial responsibilities are cutting into my slush fund.[:'(] Can't wait to get back to work.