What Header Gasket?

[Cadillac Kid]

Hello everyone.

When I bought my truck It had a pair of smog legal headman headers on it.
It has come time to put the headers back on the 350. I am a little confused on what header gaskets to get. Ive been looking on jegs and summit and seeing header gaskets with square ports, round ports, and all different dimensions.
The engine has square ports, but my headers have round ports. I am not sure what gaskets to get. Round port or square port? Here are some pictures of the exhaust ports and the headers. When I pulled the headers off, they had the cheap cardboard type gaskets on them (I don't like these).
What gasket are the proper type? Its a 1974 350 4bbl, for what its worth.

Thank you!

-Gavin

[geezer#99]

Put some stock ones on. Like this.
https://www.summitracing.com/int/par...1444/overview/

[Rickysnickers]

They are a little more expensive, and I'm not arguing with geezer at all (!), but I prefer Reflex gaskets, https://catalog.remflex.com/CHEVROLE...ket_p/2016.htm

[Jake Wade]

Felpro 1444 is the ticket for your set up. I am speaking from experience.

[crewcabshorty]

I use red RTV. I used to try all different kinds and styles of gaskets. A old racer told me to try the rtv . I havent had a leak since.

[TrailerTrash]

Originally Posted by Jake Wade

Felpro 1444 is the ticket for your set up. I am speaking from experience.

2nd. been running these for 3 years. reused them twice with no isssues

[Cadillac Kid]

Thanks for the quick responses everyone.

So the felpro 1444 with the square ports will seal even with the round header ports?

Thank you.

-Gavin

[donut]

Originally Posted by Cadillac Kid

Thanks for the quick responses everyone.

So the felpro 1444 with the square ports will seal even with the round header ports?

Thank you.

-Gavin

Yes.

FWIW, I also like the Felpro 1444 (stock type) on my smallblocks. My 454 got red RTV and held up well until it spun a bearing.

[Nick_R_23]

If you want an absolutely leak free gasket with zero maintenance, use the stock metal faced gaskets that you would with OEM manifolds. I've never had an aftermarket gasket come close to how well these work.

[LT7A]

If you want to see some real world testing of different setups, search Gregski's build of Rusty. It's good entertainment and will give you some background. I have no personal experience with headers and have no reason to doubt any of the advice previously given above. I plan installing a set in the near term, so I jumped on this thread to check out the advice. I just remember Gregski doing a lot of experimenting -- he may have actually gone back to exhaust manifolds. In which case I apologize for pointing you in a direction that doesn't offer a solution.

[jjzepplin]

I always file down the raised portion to be flush with the flange on the header itself. Then I make a relief cut on the flange between the first port and rear port leaving 3 separate bolting flanges. Then I use an aluminum gasket made by "Percy's". No leaks. I also use "Percy's" Flange gaskets. I also like to use the longer header bolts for the head. I made a special wrench for fitting the harder to get to bolts. A 1/4" drive socket and extension help to get in there too. A lot of work but the pay off is nice and maintenance free.

[GRADYS Performance]

Use a gasket that matches the Port Shape of the header. Fel Pro Performance gaskets # 1426 or Mr Gasket Ultra Seal #5907 will give excellent results. There are others as well. Square gaskets will not seal at the corners on the round header flange. After running the engine through a heat cycle go back and tighten all the header bolts. May want to do that several times. You should be leak free at the head. The collector gasket and sealing can be another area of concern.

[El Dorado Jim]

I am not sure what gaskets you need at the head, but at the collector, use the aluminum ones, they seem to be holding up fine on my 454's

[Cadillac Kid]

Thank you for all of the great response everyone.

I picked up felpro-1444 manifold gaskets today, and Installed the headers on the motor. They matched the heads perfect and the header ports pretty well.
I got them snug and will re torque them after a few heat cycles. I'm going to pick up the soft aluminum collector gaskets as well. I know the collector can be a problem area.

Thanks

-Gavin