Grade 8 is probably overkill and yes, you run the risk of cracking one or both of the castings. The intake and exhaust assembly does not need to be cranked down. The inside clamp bolts are 15-20 foot pounds, the end clamps are 25-30. Really it is just a clamping action as the intake rings and the end dowel pins on the head provide the horizontal and vertical stability. The bolts provide the just clamping/holding pressure, not to hold the assembly in place. And no, it is snot a good idea to replace the dowel pin on the head with a bolt. You could easily crack the exhaust manifold. Trust the engineering on this one, its been proven for nearly 100 years. The only reason to replace the dowel is if you are running tube headers. So if the stock hardware is not badly pitted, they are generally reusable. Otherwise, I would use grade 5 to get the proper stretch. I would also use a Rimflex gasket. They are a one piece gasket and work/seal way way better then the stock type gaskets.
Last edited by Dragsix; 03/17/2020 2:24 PM.
