Thanks all for your suggestions. The 8s and 10s tinnerman washers both work
with the 10-32 flathead screws. I'll use the 10s to insure a better grip. The
holes in the cowling itself are now about 1/4 inch in diameter and I think the
10s washers will work OK just so long as I choose the correct epoxy to get the
washers to bond to the cowling after all is aligned correctly. I have heard
that the "metal weld A/B" works pretty good with bonding washers to fiberglass.
The cowling was initially designed to use tinnerman washers ...the problem is
the holes just got bigger due to normal vibration and I would like to fix it so
this won't happen again for a long time if possible.

Larry