CJ to FSJ 258 Exhaust?

[Ralph]

There seem to be a bunch of exhaust systems available for CJ/YJ types but nothing listed for a 6-cylinder FSJ.

I'm curious if a CJ/YJ system would cross under the oil pan and line up okay with with the stock exhaust on my 82 Wag.

Anyone out there who can advise me?

I'm looking at Borla and Dynomax systems, or even yanking a nice stainless header/manifold off a mid-90's 4.0 vehicle.

[UnkleMunky]

Hopefully someone else will have a better "for sure" comment, but here's some points to consider:

1) Yes, as you noted, you can get headers, etc. even from JCW for CJs with 258s, but not FSJs. Thus, that has made me think that it's not as likely, but not 100% sure.

2) Bear in mind that different trannies, etc. can make a difference. For instance, a '78 J10 with a 258 has different exhaust pipe(first section before muffler) for a 3 speed than it does for a 4 speed. Also, it's a whole different system for 80+ models versus 79-back models. All this due to different trannies/t-cases. Thus, you need to bear trannies, etc. in mind when running pipes out too. That would make me think "the same" setup(engine/tranny/t-case) might mate up, but otherwise not sure.....either way, it's best to get measurements or "been there done that" advice from someone!

PS: You could also look into having a custom shop fab the first section too...sometimes they are cheaper than pre-bent parts. Also....even if something doesn't line up, it isn't impossible to get it to mate up with what you've got, but the closer it is initially, the less BS you need to go through to mate things up(obviously).

That's a little to think about.....wish ya well!

[ May 04, 2003, 11:50 AM: Message edited by: UnkleMunky ]

[turtlejoe]

Hey Ralph, I'm pretty sure that the manifold from the 4.0L will not mate up properly with the 258 head. I've been doing some reading on swapping the 4.0L head onto a 258, and it's required to have the newer manifold - something about the exhaust ports being located a bit higher on the 4.0 head as opposed to the 258 head. The converse should then be true that a 4.0 exhaust manifold will not fit a 258.

There's a fair bit of inference on my part, but it should be something to verify prior to swapping money for parts.

[Ralph]

That answers a lot of questions, turtlejoe. I've been wondering why Sloop had to remove the brake vacuum booster in order to get a 4.0 enigne in place. I did some measurements to see if a 4.0 EFI intake manifold would clear the master cylinder if I bolted it onto the 4.2 head.

I know the 4.0 head has a better intake angle for better flow. It makes sense that it would be taller than the 4.2 head, which in turn would cause the clearance problem for Sloop.

[Narnian]

Just fab it. You're gonna go crazy trying to find something to squeeze in there.

And get off the phone. Everytime I ever call you your phone is busy!

[sloop]

Hey Ralph- on my '93 4.0L that I swapped into my Wag, it still has headers that the previous owner installed for his YJ. They are dual headers and I had to get an exhaust shop to bend 2 very tight pipes from the headers into a Y-pipe where they connect on the passenger side. Anyways, if you get a header I recommend getting one with a single output. Although having dual might not be a problem if your driveshaft is on the passenger side.

And the intake manifold is simply a lot wider for a 4.0 than for the 258.