LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Header gaskets

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Old Jun 28, 2025 | 09:45 AM
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Default Header gaskets

What headers gaskets should I use? I have a set of hooker headers 1 5/8 primary shorty. Pn 2062 headers. I can't seem to get these to seal. It's showing I'm running lean on my wideband at wot. But I pull the plugs and they look good. Also the car pulls excellent. I don't know what gaskets to use that will fit being the headers are round and the ports are d shaped. Anyone else have this problem. I can hear the leak again on these I'm getting kind of fed up with them.
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Old Jun 28, 2025 | 10:26 AM
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You can try Percy's Seal-4-Good gaskets but the flanges on your headers may be warped slightly. The right thing to do would be to take them to a machine shop to get them milled flat. I had the Percy's gaskets on mine and blew one when a header bolt backed out. I find I need to tighten my header bolts frequently to stop leaks.
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Old Jun 28, 2025 | 10:46 AM
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Should I use a d port shaped gasket or the round which is the shape of the primary tube. I'm at a bit of a loss to get this to seal up
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Old Jun 28, 2025 | 10:55 AM
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Originally Posted by stingr
Should I use a d port shaped gasket or the round which is the shape of the primary tube. I'm at a bit of a loss to get this to seal up
The important thing is to make sure the flange doesn't cover the top of the exhaust port. The gasket shape isn't critical as long as it doesn't block the port. If the flange does, you will have to grind some to smooth out the transition.
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Old Jun 29, 2025 | 06:24 PM
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You wanted D port headers but most are round. Look into Remflex gaskets. Get a round gasket the size of the header tube opening on flange
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Old Jun 29, 2025 | 07:04 PM
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The GM exhaust manifold gaskets are one of the best you can find.

But as already mentioned, you need to make sure your header flanges are flat.
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Old Jun 30, 2025 | 11:36 AM
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Originally Posted by stingr
Should I use a d port shaped gasket or the round which is the shape of the primary tube. I'm at a bit of a loss to get this to seal up
Fel-Pro 1406. Make sure to torque from the inside out. Make sure to re-torque header bolts after a few heat cycles as they tend to shrink. If it still leaks the header flanges may not be true.
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Old Jul 1, 2025 | 08:46 AM
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Best Header Gaskets I have used are "Remflex" . Sealed my warped headers.
Depending how hard to remove your header(s), would highly recommend having them cut flat.
And to Double (or Triple) check header bolts, especially on warped flanges.
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Old Jul 5, 2025 | 05:38 PM
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Ironically Remflex notes re-torque of header bolts not needed. They are thick gaskets. I use Felpro 1406 on LT1 heads. Used the Remflex on my 327 in my 67 with stock heads
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