Originally Posted by Glowgeek

Thanks for the link John, I had no idea 5/16-32 was a standard! That changes everything. Makes it possible to fab my own insert using my wood lathe.

Just got off the phone with Time Fastener Inc. They have never made a 1/4-32 Bigsert. They also have never made an insert from brass either. Both of the ones used in this engine are made from brass. I'm thinking you're correct, someone fashioned the inserts themselves.

I will give it a shot, worth a try.