Gasket

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Yote

Yote

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Re: '72 340.
Finally fired up today, it's been sitting since August, while doing suspension and a lot other. Have a pretty good exhaust leak between head and manifold (stock). PO said only about 200 miles since engine rebuild. Torqued bolts, they were all loose. Still have leak, not any less. Question- any gaskets better or preferred over others? Other issues or causes to look for when manifold is off ?
Yote
 
If manifold was loose, and leaked, you will need to replace with a new gasket and torque to correct specs. DO not break off a bolt by tightening too much. The front and back bolt have water behind them, should use teflon tape on them to prevent leaks. Make sure manifold surface is flat no burn trails. Use whatever gasket you want, they all should work ok. I use the factory type with no problems, Fel Pro.
 
If you use the cardboard type of gaskets, soak them in warm water for a while before installing them to help them swell up and seal better...
 
You should make sure the cylinder heads don't have the AIR holes under the exhaust ports. If they do, no amount of gasket or tightening will stop the leak.
 
Not sure what you mean by air holes . The leaks all appear to be on The bottom side of the manifolds. Are the conical washers a mandatory part of the installation?
Yote
 
Look at the heads under the manifolds under each exhaust port. If there is a small hole under each port, that is your problem.
 
Yote said:
Not sure what you mean by air holes . The leaks all appear to be on The bottom side of the manifolds. Are the conical washers a mandatory part of the installation?
Yote
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AIR means Air Injection Reactor which is the proper name for the air pump. It's job was to pump air into the exhaust flow to heat the catalytic converter up to its correct operating temperature.
 
Yote said:
Would the fix then be new heads?
Yote
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No. Much simpler than that. you can tap each hole to 1/4" and use set screws to seal the holes shut. The exhaust manifolds will have to be removed though.
 
RustyRatRod said:
No. Much simpler than that. you can tap each hole to 1/4" and use set screws to seal the holes shut. The exhaust manifolds will have to be removed though.
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Good to know. Exhaust manifolds definitely coming off to check anyway. I am relatively handy but short on the knowledge you guys posses. I appreciate it very much.
Thank you!!!
Yote
 
Yote said:
Good to know. Exhaust manifolds definitely coming off to check anyway. I am relatively handy but short on the knowledge you guys posses. I appreciate it very much.
Thank you!!!
Yote
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I have never had a problem with the Fel Pro exhaust gaskets either, so follow RRR's advice and you should be all set.
If you find you have some irregularities in the sealing surfaces you can use a small (1/8) bead of the red hi temp rtv on both sides of the gasket and that will take care of that. :D
It would have to be jacked up pretty bad to need the rtv though.
 
Having already found so much (jacked up) by PO nothing much would be much of a surprise now.
Yote
 
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