What year header applications fit an '87 Xj?

Got the infamous crack on the manifold. Would like to replace with a header. Doesn't have to be anything coated or fancy. I see most of them start at '91. So what fits an '87?

Thanks
-Paul

try the pacesetter header o nsummit. its pretty resonable as far as price goes. and i think it comes with the S pipe too.

Twilightoptics said:

Got the infamous crack on the manifold. Would like to replace with a header. Doesn't have to be anything coated or fancy. I see most of them start at '91. So what fits an '87?

Thanks
-Paul

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1987-1990 XJ/MJ. 1991-up will lack the port for the EGR tube, and I think ChryCo also redesigned the downpipe and moved the collector flange slightly as well.

While you're changing out the manifold, replace all three of your engine mounts. Seriously consider adding some variety of flexible joint in the downpipe (cut and weld,) which should help the longevity of your header. Apparently, most manifold cracks are accompanied by failed/failing engine mounts (allowing the engine to move - but the pipe and connection stays rigid.)

yeah. Chrysler moved the collector flange down about 9-10", went to a split type collecter set-up (3cyls. into a down tube, then merge at the flange for the head pipe to bolt to). They also changed the headpipe angle, so now, you need another headpipe, or at least the front section to match the collector. Also, the RENIX intake sits closer to the head than the H.O. set-up, so the later manifold will end up holding the intake back from the head.

I'll do the motor mounts same time then. Good information to know. I am assuming since the intake and ex/manifold seem to share bolts, the intake has to come off for this?

Twilightoptics said:

I'll do the motor mounts same time then. Good information to know. I am assuming since the intake and ex/manifold seem to share bolts, the intake has to come off for this?

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Yes, you are correct.

Retain those bowl-shaped washers for reuse. Replace the screws. I like to use silicon bronze or brass, but I can usually get parts a couple of days out (so I can get away with ordering from outfits like Fastenal when I need something "exotic".)

If you're in a hurry, you can use regular steel screws, but I strongly recommend using SAE5 instead of SAE8 - Grade 5 is less sensitive to heat cycling and will lose a much smaller percentage of its strength over time (as I've said before, I've verified this experimentally. IIRC, it was after something like 25-30 heat cycles where the SAE8 was on a par with SAE5, and thhe 8's were actually getting gradually weaker than the SAE5 afterwards. The heat cycles tend to soften iron/steel alloys - it's called "annealing" if you want to look it up.

Either way, replacement screws (for RENIX, and probably later models as well) will be 3/8"-16x1-1/4" hex head capscrews. You won't have enough vertical clearance over the head to use any sort of socket head, but you will find a shortly 9/16" "flex" socket (inbuilt universal joint) to be well worth the money - the extra inch is valuable.

The funky washers are there to help keep the screws from loosening - aluminum expands twice as much for a given temperature as iron/steel does, and that will generate a "twisting" force on the screw - which causes it to loosen.

When you install the new gasket; a light, even coat of RTV copper (use no other sort! won't go amiss, either. It not only helps the gasket seal, but it also helps prevent burn-through for when the screws loosen. I tend to use RTV copper on all my exhaust gaskets - save the donut packing at the collector flange.

If you want to use threadlocker, use LocTite #272 (or equivalent) or nothing. Nothing else will hold up under exhaust heat - other grades of threadlocker will break down and become useless about the third time you drive for more than ten minutes.