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Discussion Starter · #1 ·
I could use some help guys. I've got an exhaust leak at the manifolds that's giving me a hard time. I torqued incrementally on the eng stand and during break in leaked what I thought was way more than I'd expect. Mostly passenger side. I went back and got a little turn on several bolts and noticed a decrease, but still leaks. Is there a trick I should know? I'm considering removing bolts one for one and lubing the threads. It's been wet here so haven't tried laying under the car, but I'm thinking I may need to modify a wrench or socket to get more leverage. I'd hate to keep tightening if a gasket is misaligned, but I eyeballed it carefully at install and looked at the alignment. I'd hate to pull the manifolds off or worse pull the engine, but it's keeping me from moving forward. The hood's still off. Will run time hurt or help. I've only got two breakin runs no more than 40 minutes time in neutral... need a push in the right direction. Tips?
 

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i'm not an expert, but from what i have been told, you need to start off with a really good gasket. this is one case where you definitely get what you pay for, from what i am told, copper is the best. also, since you said you are installing manifolds, you shouldn't be having a problem with the manifold not crushing the gasket sufficiently since they are made of thick cast iron. with headers whose flanges are thin, the force is not evenly distributed enough between the bolts so you'll get a leak in the middle.

second, after torquing the bolts to spec, run the vehicle till it gets hot and re-torque all the bolts (since the hot metal expands and loosens the seal). repeat this a few times till they stay at spec.


hope this helps, but like i said, its just what i have been told to do.
 

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They don't use gaskets.
Stock manifolds from the factory no gaskets
You can use a little high temp copper rtv
 

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Discussion Starter · #4 ·
Thanks for the help. I heard no gaskets today from a fried of mine. Just hard to imagine unless you go with red RTV maybe that's way more conforming than a gasket.
Since I got several people telling me it will settle some during the heat cycles, I'm going to put some run time and retorque bolts several tries first. I really appreciate your thoughts because as you know out there in the driveway staring at my progress each day it's mostly me... good to hear your input.
 

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If its like my 68 390 FE they didnt use Gaskets from the factory you can have the manifold resurfaced and use antiseize on the manifold between it and the block and it wouldnt hurt to put some on the bolts but some are using the copper gaskets with luck.
 

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Discussion Starter · #6 ·
So I ran it for another 20 minutes or so and took it around the neighborhood and then I was able to tighten about 5 of the exhaust bolts 1/2 flat or so and I'll do so another couple times before going another route.
 
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