These are two bolts used to attach a starter on a big block Chevy. One of them obviously has slight problem and that problem is still located inside the block.
My question is this- notice the metal mesh pattern near the threads. Both of these appear to have deformed near the threads. Is this a thread-locking feature that is designed to prevent these from backing out? They both obviously made contact with the block and got necked down a little.
Fyi, I’m trying to extract the broken stud without pulling the engine out. It’s a horrible inverted blind reach. And no… I’m not the one who broke it off
I think the knurling is just there to accurately locate the starter without any play. It would essentially act like a pin, with the knurling going partially into the block, and also partially in the last bit of the starter bolt hole.
I think the necked down part is just a thread relief, a normal feature.
This bolt hole is in a really awkward spot. Imagine laying at the front of the engine and reaching under the motor mount toward the back. You can touch the bolt hole with one hand, but you won’t be able to see it.
My plan is to spot weld a stud onto the bolt. I’ll make a non-conductive guide to locate the stud in the middle of the hole, and prevent it was welding to the block.
I built a “simulator” to practice on with at the same hole geometry. After figuring out the right welder settings and technique, I did it on the real engine.
