Hi guys,
I did the crockpot clean on several engines that had set up too long.
One of these was an OS FP40 that Randy Smith had setup.
I had taken off the back plate and when I started to put it back on I found that one of the holes in the case had stripped when I had disassembled the engine.  Question : What do I do?   I vaguely remember hearing about someone tapping out a stripped hole with a 5-40 tap and then using  a 5-40 screw and I noticed that Micro Fasteners has both of those items available.
 So, what do you guys reccomend as the best way to go?

                                                      Pat Robinson

  not knowing what size was in there  stock,  You might be able to install a 4-40 heli-coil and that reverts the thread to a 4-40 screw.  If it was already a #5 size, and then stripped out, I believe the hole would be too big to install a 4-40 heli-coil.

  Bigiron

The stock screws are 3mm x .5's currently standard. The old standard was 3mm x .6's (ST .60, ST .46, OS .35S, etc.).  The standard fix for these engines, now that those 3m x .6 screws are pretty much unobtainable, is to use 5-40's.

Therefore, there is not going to be any material to tap, to screw the 5-40 into. A 3mm x .5 helicoil would be the right thing to do, and maybe the only thing to do. It might be cheaper to find somebody to fix it, than buy the drill, tap, and helicoil plus the installation tool. OTOH, if you have to pay postage both ways, you might be better off buying the drill, tap, and helicoils and make your own install tool from a machine screw. Or, you might be able to buy a new crankcase from Tower? I'd sure look.  Steve