Exhaust Manifold Gaskets

[John Bauer]

The factory did not use any gasket between the exhaust manifold and the cylinder head on '71 small block. However, Fel-pro offers gaskets for this application. After restoring the heads and manifold, would a gasket be needed or would they seal as they did from the factory?

[Joe L.]

Re: Exhaust Manifold Gaskets

John----

No gaskets are needed if the manifolds are relatively flat and true, as most are. These exhaust gaskets have been provided as part of gasket sets manufactured by many vendors for years. I've NEVER used one.

[Wayne M.]

Re: Exhaust Manifold Gaskets

John & Joe: I'm a little more pessimistic than Joe, but it depends on how much concentrated driving you do. For any extensive use, say 8+ hours a day for several days, I'd suggest the following: lay a steel straight edge both on the heads and manifolds -- don't accept any gaps, or, if you absolutely must retain the factory appearance, get under the dash in a darkened garage while a helper shines a trouble-light around the firewall. Especially check for a worn or torn clutch rod boot, leaks at factory grommets (tach, speedo, and wiring harness) and possible non-factory holes. I assume you'll be installing new manifold-to-exhaust pipe doughnuts, but still check for blow-by with your hand for the first few seconds (while the joint is not yet hot). Also your shifter boot should have no holes/cracks.

Yup, I've been there, inhaled that. ------ Wayne

[Jack H.]

Re: Exhaust Manifold Gaskets

Agree with ALL advice given by others. On initial rebuild of my '71 SB the RH exhaust mani leaked modestly. When I pulled both mani's and had them trued to flat, leaks disappeared and have remained in check for +28K miles.

BUT, the factory used thick washers under the french locks at both ends of the manifolds (none in the center). In my opinion, these are there to absorb threads, keep the bolts from bottoming out in the head and keep the manifold casting in tight contact to the head (prevent warp/creep). I'd suggest you have the head mating surface of your exhaust manifolds checked for true/flat AND use correct fasteners when you install.