On my 1970 350 gas block The machine shop that decked my block removed and lost the locating pins that locate the heads to the block .....He gave me some Chevy ones that are 5/16"....I checked the block and the heads using a 5/16" drill bit and They seem to work fine in the head but the block appears to be slightly smaller than 5/16"... What are they supposed to be and or if they are an odd size for the block side where do you obtain them..

 

The pins are supposed to be a tight press fit in the block.

 

If the pins your machinist gave you aren't a tight fit then have him mahcine you some that work.

 

I would tell the guy to get the proper pins after all he lost them. You paid for a complete job not part of one I assume. I would be concerned about the rest of the work he did based on this