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351c exhaust gasket donut question
#1
Question does the dual exhaust on a 351 Cleveland with boss manifolds use a doughnut exhaust gasket between the exhaust manifold and the H pipe?

I can not find mention of one. my exhaust pipe is flanged to accept the flair on the manifolds I have, I never used a gasket there before but I know I have a small leak from that mating point, plan is to use some exhaust sealant at that point unless there really is a gasket designed for it.. If there is one I need a part number for it.


I found a C9ZZ-9450-D gasket but there is no way it would fit the manifold and pipe I have.
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#2
I have never seen a donut gasket on a 351c exhaust manifold. To stop leaks I put a floor jack under the pipe right at the bend and add slight up pressure. I tighten the flange nuts with the jack in place and walla, the leak is gone.

72HCODE;185669 Wrote:Question does the dual exhaust on a 351 Cleveland with boss manifolds use a doughnut exhaust gasket between the exhaust manifold and the H pipe?

I can not find mention of one. my exhaust pipe is flanged to accept the flair on the manifolds I have, I never used a gasket there before but I know I have a small leak from that mating point, plan is to use some exhaust sealant at that point unless there really is a gasket designed for it.. If there is one I need a part number for it.


I found a C9ZZ-9450-D gasket but there is no way it would fit the manifold and pipe I have.
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#3
No doughnut except on police cars.Tongue A small amount of RTV on both mating surfaces, tighten, and let it completely cure. It won't leak and it won't burn out. Same for header gaskets. Chuck
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#4
Thanks for confirmation.

I used high temp ext sealer and finished the exhaust today.. 2 projects down. Yippy.


c9zx;185704 Wrote:No doughnut except on police cars.Tongue A small amount of RTV on both mating surfaces, tighten, and let it completely cure. It won't leak and it won't burn out. Same for header gaskets. Chuck
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#5
Good for you. The hobby is a lot more fun when things go well. Chuck
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#6
I've had great luck with the ultra copper high temp rtv on exhaust systems. Particularly FE header gaskets.

1973 Mach 1 Q code 351 4V, 9A paint, standard interior, 3.50 rear, C6 trans.
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#7
I found the metal to metal seal technique required excessive pressure tightening on the exhaust stud nut so I purchased some bulk pieces of exhaust gasket from summit and cut out a doughnut shaped piece of gasket and placed it over the end of the exh manifold and tightened the pipe over the gasket and got a good seal with moderate pressure on the stud nut.
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