409 head bolts

La Hot Rods

Well Seasoned Member
Supporting Member 15
I'm not sure if they are or not, they has a small shoulder just at the boss like a screw in without the hex.
 

64ss409

Well Known Member
Supporting Member 9
It could be an oversize stud. They used to come in std., .003 over, and .010 over. They had to be reamed with the proper reamer for the oversize or there was a chance of cracking the boss.
 
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