rod bolt size

[superdawg]

I cant figure out what rod bolts I have. The threads are 7/16 and the head uses a 7/16 socket, but the part between the two is smaller. What size bolts do I have? 3/8 because the part in the middle is smaller or 7/16 because of the threads. ARP 8740 if you needed to know.

[ptodd]

standard arp 8740 7/16 rod bolt.

[let-r-eat]

The type of bolt you describe is definitely a 7/16 as ptodd has mentioned. This is known as an "undercut" when you have thread size larger than thread.