351w Header Gaskets/Liberty Heads

[jwebb]

A exhaust leak has developed on a couple of ports, will replace the gasket and re-torque. Suggestions on the best brand of gasket to use?

[Papa]

A exhaust leak has developed on a couple of ports, will replace the gasket and re-torque. Suggestions on the best brand of gasket to use?

I was strongly urged to use copper RTV and skip the gaskets.

[jwebb]

Thought copper RTV was good up to 700 degrees F? How do you apply in a header application?

[Papa]

Thought copper RTV was good up to 700 degrees F? How do you apply in a header application?

There are lots of threads debating the use of gaskets vs. copper RTV. When I asked Georgie from Gas-N what he recommended, he emphatically recommended copper RTV. It seems to work in spite of the rated temperature of 700 degrees.

[Bob Cowan]

This is a common problem, and it's because of the shape of the header port. Take a look at this picture. You can see that the shape of the header port doesn't match the shape of the exhaust gasket very well at the bottom. This is the weak spot, and eventually this will fail. Even the gasket supplied with the headers from FFR look like this. Some of the expensive copper gaskets, like Percy, are a little bit longer here and will cover this area a little bit better. But sometimes even these will fail.

https://i.imgur.com/fTWHj2o.jpg

As said above, just use some copper RTV and move on. It will last for years without a failure. Even on the race track.

[jwebb]

This is a common problem, and it's because of the shape of the header port. Take a look at this picture. You can see that the shape of the header port doesn't match the shape of the exhaust gasket very well at the bottom. This is the weak spot, and eventually this will fail. Even the gasket supplied with the headers from FFR look like this. Some of the expensive copper gaskets, like Percy, are a little bit longer here and will cover this area a little bit better. But sometimes even these will fail.

https://i.imgur.com/fTWHj2o.jpg

As said above, just use some copper RTV and move on. It will last for years without a failure. Even on the race track.

How much & how is it applied? To the head or headers??

[Papa]

How much & how is it applied? To the head or headers??

DIRECTIONS:

For best results, clean and dry all surfaces with a residue-free solvent, such as Permatex® Brake & Parts Cleaner.

Cut nozzle to desired bead size – gaskets are best formed using a 1/16" to 1/4" bead.

Apply a continuous and even bead of silicone to one surface, surrounding all bolt holes. Remove excess with knife at once. Assemble parts immediately. Do not squeeze out silicone by over tightening bolts. Re-torque will not be necessary.

Silicone dries in 1 hour, and fully cures in 24 hours, at 70˚F (21˚C) - 50% relative humidity. Allow more time in cold weather.

Replace cap after use. Clean hands with dry cloth or Permatex® Fast Orange® Hand Cleaner. Clean tools with non-flammable cleaning fluid.

[Bob Cowan]

Not a whole lot, about this much. Lit it sit for a it and skim over, and then tighten it down.

https://i.imgur.com/DKCCFSN.jpg

I get a pair of 1.5 - 2" long bolts and cut the heads off. I put them in a couple of holes and use them like alignment dowels. Then you can just slide the headers in place without making a big mess.

Get all the bolts started a couple of turns. Then go down the line and tighten each bolt 1-2 turns. If you snug the flange to the head with one bolt, there are a couple of bolts you won't be able to get in. When you get all the bolts finger tight, then you can torque in the proper sequence.

[jrcuz]

I used the ultra copper instead of gaskets. I also used ARP studs in place of the bolts supplied. Can't offer any feedback as I haven't had engine start yet.
JR

[jwebb]

Not a whole lot, about this much. Lit it sit for a it and skim over, and then tighten it down.

https://i.imgur.com/DKCCFSN.jpg

I get a pair of 1.5 - 2" long bolts and cut the heads off. I put them in a couple of holes and use them like alignment dowels. Then you can just slide the headers in place without making a big mess.

Get all the bolts started a couple of turns. Then go down the line and tighten each bolt 1-2 turns. If you snug the flange to the head with one bolt, there are a couple of bolts you won't be able to get in. When you get all the bolts finger tight, then you can torque in the proper sequence.

Bob,
Another questions, why around some of the bolt holes and not all?

Jim

[Bob Cowan]

No particular reason, purely random.