exhaust for 258

[kalve]

I am needing to replace the whole exhaust system on my 85 Eagle wagon. Was wanting to know what headers an performance cats an mufflers would be good to use on here? An what size exhaust I am planning to do 4.0 head swap etc.. come spring. Should I go with a 2.25 or 2.5 exhaust? I am thinking bout going with the 2.50 exhaust size.

[DaemonForce]

258 block, 242 head, I would use the stock 1991 exhaust header that came off of the engine I pulled the head from. At least that tells me it should work. As for the 258 head, classic stock manifold replacement should be the only major investment you make in that area. The rest is a mishmash of aftermarket internals. Since a lot has changed in 30 years, I think it's worth it. I'm always too far stuck in a bad place to ever actually do the rebuild though and I'll probably never get the chance to find out at this rate. Good luck. :/

[BenM]

The stock 4.0 tubular headers are pretty good. Somewhere here is a writeup about gusseting some connections to prevent it from cracking, and you have to do some turns around the front diff and build a new bracket, but that's not difficult or complicated stuff.

If you have a good exhaust guy, or can spend some time welding pieces yourself, I'd go 2.5 from the manifold back to the cat and muffler, then go down to 2.25 from there on out to save a few dollars. You could even order stock pieces from NAPA for the back and make life easy. You'll never notice the neck down after the muffler, and probably not even if you did it between the cat and muffler.

[kalve]

ok I plan to do the exhaust on monday an get he car to pass inspection an be on the road the exhaust shop also does inspections so I will have them do it them an get it legal.
My plans for the car:

full exhaust (already purchased magnaflow universal High performance Cat) looking to go 2.25 or 2.5 on exhaust

add headers

go with 4.0 heads ported an polished

go with Weber or Motorcraft carb

add turbo

switch rear end to Dana 44 maybe limited slip an go probably 3.0 gear

switch trans from auto to 5 speed manual

check bout removing emissions an computer depending on tests in WV rather it will pass inspection.

add skid plate protection

going to do exhaust come monday an the rest of it will be done over time. But based on all this should I go 2.25 or 2.5 exhaust on it

[kajsdf]

clifford performance makes great headers; i am using the set they designed for the eagle 258 (jeep headers sometimes have fitment issues) and they are really awesome.  i recently built a 258 by their specs and i'm impressed so far.  their products are pricy but worth it if you are looking for performance

[jim]

Did you pass inspection and get it on the road?

[TheWraith]

...well, as well as a 5.5 cyl 4.2 motor can run...)

Now that's funny right there.   

[carnuck]

Nice thing about rolling emission cutoffs here in WA. Mine is cleaner than OEM emissions anyways (NOx may be a little elevated) but I hoe to test fit my Jeep header (for HO) for clearance from the block and driveshaft in the near future. I have to complete my MJ so it can be driven and up for sale in the meantime.