Quote:
Originally Posted by mattgic
I developed an exhaust leak on the manifold. I am fortunate enough to have a new one available. So it is a complete replacement, intake and exhaust. The studs came out of the block on removal and the intake mounting bolts just sheard off.
I ordered some new studs, but it seems that the vendors sell brass nuts for the studs. Is this necessary being that this car is not a show car and very likely will never be one.
I shouldn't have any issues using grade 8 nuts for the studs and mounting bolts.
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The manifold studs are coarse thread for the block side and fine thread for the manifold side. "Conventional" Grade 8 nuts should be fine, but they are not necessary as you only put nominal torque on them (some folks say 25 ft.lb, some say 40 ft.lb, I'm in the "up to 25" camp). More important is that you use the proper dome shaped washers between the nuts and the manifolds, and install them properly (concave side towards the block). This assures that you will not put undue pressure on the outside of the ears of the manifolds, which can break.
Since you are replacing at least one manifold you should evaluate the flatness of the bolted-up assembly (intake and exhaust) before you install it. The intake and exhaust need to be coplanar when bolted together. I (and many others) use 0.002" as tolerance. If your assembly exceeds that you'll need to have the assembly decked at a machine shop.