87-90 header

if ive got the 99 intake on my 4L I6 can i buy a 91 newer header? what is it about the 91 n newer headers thats different as too why they dont fit on the 87-90. my 90 needs a header.... is it the bends?

hidesintrees said:

if ive got the 99 intake on my 4L I6 can i buy a 91 newer header? what is it about the 91 n newer headers thats different as too why they dont fit on the 87-90. my 90 needs a header.... is it the bends?

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First, the EGR valve was deleted starting in 1991, so you don't have the EGR provision anymore.

Second, apparently, various brands of header aren't bent the same way, and some will have trouble with the primaries hitting the underside of the intake. Oops.

Third - I know that the intake ports were raised in 1991, by about 5/8". Have you just the intake manifold, or did you swap the head as well? If you've swapped the head and intake, you can probably use the header - if not, it's a bit worrisome.

just the intake i havent even looked into swapping heads.. do you know of any companys good for a 90 header? itd really help thanks

hidesintrees said:

just the intake i havent even looked into swapping heads.. do you know of any companys good for a 90 header? itd really help thanks

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I can't recall any. Probably start by checking all the popular header makers - Pacesetter, Hedman, Hooker, Blackjack, and the like.

pacesetter makes a header for the renix

You can use the H.O. exhaust manifold on the Renix but you will have to use the H.O. down pipe as well.