Manifold to pipe issue: HELP

[matthon]

After attempting multiple flanges, gaskets, etc, (and even trying to make a flange), I cannot get a good seal between the exhaust manifold and the exhaust pipe. A friend of mine, who is a knowledgable mechanic, has also assisted, with no luck, (its nice that he can try different flanges and pipes and send them back, no questions asked!).
There is just nothing that will press the gasket down completely, and eventually the gasket fails.
The last resort is a new exhaust system, but there is no guarantee the flanges will be any better or different.
I have a 67 383 4 speed, so headers are not an option either, (at this time as I would have to spend $400-$800, and I still have to modify them for the linkage).

I've sealed the firewall, put a new trunk seal on, etc, but the exhaust gets in the car, and when I open the windows its worse.

The exhaust is making me ill- any solutions?

 

[mcodecuda]

If it's leaking at the flange it will sound like a lifter ticking. If that's the case you need to be sure that the flange is flat and don't overtighten it. if you do it will bend the flange and start leaking again but it sounds like in your case is that your getting exhaust fumes in the car. Do your pipes exit the back of the car?

 

[RedFish]

I'm puzzled too. Surely you're using a donut and not a flat paper gasket.
Even with the bestest mounts, the engine is gonna move a little.
The pipes need move with it. Rigid hangers too close to the engine ?
Good luck

 

[matthon]

Yep, the pipes go the length of the car right out the back.
I understand that overtightening will bend the flanges, but I've tried new flanges, different styles, and it still eventually leaks.
There has to be something available that eliminates the flange/pipe setup- something similar to the end of the manifold, (like bolting the end of a manifold to another end of a manifold), with a pipe on it. Then I could just cut my pipe and connect the two pipes.

 

[matthon]

I'm puzzled too. Surely you're using a donut and not a flat paper gasket.
Even with the bestest mounts, the engine is gonna move a little.
The pipes need move with it. Rigid hangers too close to the engine ?
Good luck

The gaskets are flat, but they have a metal ring in the center. Will a donut gasket work with the flat end of the manifold? And aren't they usually made out of a paper product that will eventually burn out?
Maybe I'm a big dummy, the donut gasket is something I didn't even think of, and not one parts store even listed a donut gasket.
And stop calling me Shirley (Airplane movie reference!).

 

[RedFish]

The donuts were once made of asbestos. I dont know what the use today.
Most of them have a short neck on the flat side that enters the manifold and a tapered side to mate the pipe. More modern assemeblies have springs on special shoulder bolts . These allow a bit more movement but can't be overtightened.

 

[matthon]

OK, I can get a donut, but I need to know the diameter of the manifold side.
Anyone know the diameter?

I called NAPA and talked to guy who knew exactly what I needed, and also confirmed that the 'computer' only listed the flat type.

FABO rules!!