exhaust cross-overs??

12-02-2002, 06:20 PM

Hello-
I recently had to pull off my upper & lower manifolds to fix a water leak at the rear of the lower manifold. I've only had my manifold off a couple of times since the rebuild so I'm not real familiar with my Edelbrock Performer RPM cylinder heads & the proper gaskets to use, etc. I did notice that in the middle of both of the lower manifold gaskets (that match up to the top of the heads) there is a hole about 3/4" in diameter inbetween the 2 center bolt holes, on both heads. I did not know until now that these holes need to be plugged with a heavy duty, coated, cardboard gasket insert thing that was supplied with my fel-Pro gasket part#1250. Last time I pulled off my lower manifold I forgot to install the insert to plug these exhaust cross-over holes. The result was excessive oil spitting out of my oil breather at full throttle. I knew something was wrong right away, even though power was the same and the engine ran perfect. I'm so glad I figured out the problem. But I still have some questions about these exhaust cross-over holes...so here they are:

What is function of these exhaust cross-over holes?

Why do I need to plug them on a 302?

I can't remember, it's been a while....but do the stock 5.0 cylinder heads have these same exhaust cross-oer holes?

The Fel-Pro gaskets set that I bought (#1250) had 2 different sets of these inserts. One to plug the exhaust holes, another to keep them open.
What kind of motor (or size?) would need to run with these exhaust holes open?

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12-02-2002, 06:20 PM	#1
Simi Stang Guest Posts: n/a	exhaust cross-overs?? Hello- I recently had to pull off my upper & lower manifolds to fix a water leak at the rear of the lower manifold. I've only had my manifold off a couple of times since the rebuild so I'm not real familiar with my Edelbrock Performer RPM cylinder heads & the proper gaskets to use, etc. I did notice that in the middle of both of the lower manifold gaskets (that match up to the top of the heads) there is a hole about 3/4" in diameter inbetween the 2 center bolt holes, on both heads. I did not know until now that these holes need to be plugged with a heavy duty, coated, cardboard gasket insert thing that was supplied with my fel-Pro gasket part#1250. Last time I pulled off my lower manifold I forgot to install the insert to plug these exhaust cross-over holes. The result was excessive oil spitting out of my oil breather at full throttle. I knew something was wrong right away, even though power was the same and the engine ran perfect. I'm so glad I figured out the problem. But I still have some questions about these exhaust cross-over holes...so here they are: What is function of these exhaust cross-over holes? Why do I need to plug them on a 302? I can't remember, it's been a while....but do the stock 5.0 cylinder heads have these same exhaust cross-oer holes? The Fel-Pro gaskets set that I bought (#1250) had 2 different sets of these inserts. One to plug the exhaust holes, another to keep them open. What kind of motor (or size?) would need to run with these exhaust holes open?