Header Flange Not True

[1987 GMC Jimmy]

I have a set of headers that I really want to throw on the Jimmy. They’re G Body headers I got from Craigslist like two years ago. Guy said he LS swapped his Monte and had no use for them. I took a straightedge and checked the flanges for trueness. One was perfect, but the other, if you centered the straightedge in the middle, had about .5 mm of play on either side. Very little but still not perfect. Is this tolerable, or are the headers no good because of this? I’ve heard of leakage issues on even new headers so I don’t want to waste my time if these are a shady prospect.

 

[Snoots]

I sandwiched 2 material gaskets between 1 metal gasket about 25 years ago. No leaks yet.

 

[dvdswan]

they make 1/4" or 3/8" collapsible flange gaskets now.

https://www.summitracing.com/parts/...MI1MGVvsun3AIVA7vsCh0qcw5FEAQYBCABEgLuuPD_BwE

 

[bucket]

A quality copper or aluminum gasket will seal it up fine.

Are these long tube headers or mid length? Mid length headers meant for a stock type Gbody y-pipe may not fit.

 

[1987 GMC Jimmy]

A quality copper or aluminum gasket will seal it up fine.

Are these long tube headers or mid length? Mid length headers meant for a stock type Gbody y-pipe may not fit.

Should have clarified this. These are long tubes. They caught my attention because I figured the they would tuck nicely kind of like the A Body headers people have mentioned in the past.

 

[peats]

before i would worry about the warp, i would check to see if they will actually fit your truck.

 

[shiftpro]

Should have clarified this. These are long tubes. They caught my attention because I figured the they would tuck nicely kind of like the A Body headers people have mentioned in the past.

Tighten the buggers down..
Well hope the long tube works for you as these make the best power for low rpm.

 

[78C10BigTen]

Ive always been told by dirt track guys to cut the flanges off in between them so each pipe can flex themselfs and stay tight. Idk how well it works but ive seen it done. Not as fancy but kinda like so...

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