1990 exhuast manifold ?

[chunkswood]

hey everbody i am new to this forum and have 1990 4wd 4.0 auto. the truck is stock so far and will most likely stay that way for now. it needs a gas tank and exhaust manifold and some other small stuff. my ? is can i put a 2000 and newer manifolds on my renix head? it won't have to inspected so i could do away with the egr valve. it will need all new exhaust anyway and i have a good connection with muffler shop so i was thinking about true duels. maybe even some stacks! their are 2 reason i want to use the newer manifold 1 being that they are cast so i don't think the will crack as easy, 2 and the most important reason is i all ready have them. i had cj5 with a split header and that thing sounded sweet.

thanks andrew

[jimoshel]

They will bolt up OK but the ports don't line up so basically it's a no-no.

[chunkswood]

i have gasket coming tomorrow and was going to see how close the ports were. could i portmatch them you think or is it to far off?

[jimoshel]

It has been done. The manifold is lower than the head so it needs to be ported down. There's not enough metal so the underside of the manifold is built up by welding. I think if I was going to go to that much trouble I would just get a piece of steel and cut it to match the head ( or just cut the flange off the manifold) and then weld tubing to it, making my own set of headers.

[88pioneer]

As jim said, the ports don't line up between the older and newer motors. Also, you can't run "true" duals on a 4.0 as there is only one exhaust manifold