Starter Bolt Fell Out!

[TheRoaringEagle]

I was using a CSR Mini Torque Starter and it kept coming loose. It had an adapter for my 400 staggered bolt design. I put the stock starter back on with new starter bolts and the engine turned great. Then after a few weeks the starter bolt outboard of the engine fell out. It looks as though the threads are gone in the block.

How do I fix this? I was thinking of using a long bolt that went through the mounting hole and using a nut to tighten it down... I didn't have a starter brace on and I'll be putting it one one soon. Anybody in the San Francisco area know where I could get this fixed? (threads on block)