`Could someone tell me what is the best high temp silicone to use on headers? I beed having problems with the headman headers gasket . I have tryed two headman gaskets and one cooper gasket still cant stop the leaks.

 

If they are fairly old they may have a couple of tubes that are cracked. You have not bottomed out on them have you?
If they are new, than you may have to use washers under the header bolts. Sometimes the bolt head sinks down into flange and will not hold enough.
Gene

 

Yes they are new . I called headman they said to hand tight the frist time start the motor 4 times then wait 24 hours then retork them to 20lbs.nothing works.So i thought that i would try high temp silicone i just dont know what is the best to use is the red silicone verry good ? or will it burn off? Or should i get them mild becouse flat of the flang there is not much there to seal and have them welded the pipes on the out side?

 

Mike, if two of the gaskets didn't work for you then you have no choice but to try the red/orange rtv.

Have you tried to leave out the center bolt with any of these gasket changes? Just use four bolts see what happens.

 

I will try that thank you for your help. IF THERE IS EANY MORE INFO .I COULD USE

 

I have the same issue with my set. fresh out of the box they leaked. no amount of RTV or sealer is going to help. You are going to have to have the gasket side ground flat. Keep in mind you will probably grind through the weld and need to have them re-welded. you need to weld on the flange side, not the outer side.

 

I have run across the problem where the gasket was not sealing at the top. The 455 has a higher ex-port ceiling than the 350 and gaskets are made to fit the 455 thus the sealing ridge on the header sits a hair below the top edge of the port hole in the gasket making it leak. A few companies make header gasket material and you can cut out your own with the proper size port.

 

RTV will burn and blowout!! In the past I've used 2 Mr Gasket header gaskets on each side, but first I would lay them in a pan of water for about a half hour and let them expand. Install wet, torque them down, start the engine and re-torque hot. Snug the end bolts first and work towards the center.

 

So would it just be better to go back stock? Ihave 200$ in headers but it sounds like it will cost a nother 200? to fix them.

 

How much power would i lose going back stock?