5/16 wrenching header bolts

Fishy, thanks for the tip, I never thought about reverse engineering my problem. Those are sorta like the ignition wrenches only larger right? I'd still like to find those damn bolts.....They make em in 3/8 for all the damn chevy and ford guys. Just got confirmation from arp that the bolts above are in fact 3/8 wrench size.:(