I have fender exit headers on my 304 right now. Don't like um. Flanges are bent so I go through gaskets constantly, and my mufflers do rock slider duty.
Well, I'm going to be dropping in an 11:1 forged piston big cam etc. 401 in soon and want to fix the exhaust at the same time. Should I go with inside the frame headers or manifolds? I don't want the manifolds to cork up the top end of the motor, but they should do OK with low rpm torque. Headers would be ideal but in my limited experience with them leakage is a constant issue, plus I don't know how well aftermarket stuff will fit. This on a 77 CJ-5.
Did AMC make any manifolds that will work well at 400+ horsepower?

Thanks...

i have a CJ7 with a 377hp built AMC 360. Let my misery and waste of hard earned $$$ be a lesson to you, get a set of 304 manifolds, bolt 'em on, and be happy!! i tried fenderwell headers, they suck for the reasons you listed, I bought a set of Hooker Competition inside the frame headers, they wouldn't work with my other mods (driveline), and leaked big time. Not to mention they were loud as shit, oh yeah it sounded great but a built motor thru headers and flowmasters does get annoying after the novelty wears off. If you dont believe me ask my neighbors! Finally i bought a pair of 304 manifolds from a PNP for $30. I welded up the smog bosses and bolted them on. No leaks!! I ran a 2 1/2 "Y" pipe under the bell housing / tranny to a 3" pipe to a 3" flowmaster Delta Series 3 chamber muffler, then out the back. I lost nothing in terms of power, besides how often do you turn 5000+ RPM's?

If you insist on headers drop me an email and i will sell you a pair of Hooker Competition inside the frame with copper collector gakets and reducers for $100. They were run for less then 1 hour total.

Mike

Good headers (w/ thick flanges aka Hooker Super Comps) will not leak provided you bolt them up good. Stay away from the cheapies though. They will warp and rust in no time.

On my SBC CJ I ended up using regular truck manifolds for an inside the frame job. The crossover is behind the transfer case towards the driver side where it goes to a series 40 flowmaster with a single out. 2.5 inch all the way. If I ever decide to lose the manifolds I can just drop in a set of regular shorty truck headers. I personally like the edelbrocks.

My rev limiter is set for 5 grand. Unless your bogging it in the mud, I doubt yor motor will see more than 5K. That is unless you went to the Daisy Duke school of driving. :flipoff2: :D

Mike, do you have a pic of your crossover pipe? If I ever do this again, I'd like to do a crossover up by the motor, maybe infront of the hump in the SBC oil pan..

MANIFOLDS! MANIFOLDS! MANIFOLDS! MANIFOLDS! MANIFOLDS!

Headers SUCK. I had hedman inside frame headers on my 360. anywhwere a header can leak, they leaked. went to 304 manifolds, perfect. no problems

Go with the 304 manifolds, the 360/401 manifolds aren't the same and don't flow as well. They will bolt up and work fine, but the 304 ones are a much better design.

It'll turn 6500 rpm. I guess I don't need it much though, mostly sand, and probably need torque more than rpm 99% of the time. I don't mud race.
So you say 304 manifolds flow better than 360-390-401 ones? Anybody else back that up?

Thanks-

Run the 304 manifolds and match port them to your heads and run a x pipe or an h pipe with 2.5" to help it flow at high rpm. With this setup you should'nt have the problems that come with the headers but still have a good flowing exhaust.

Here is what I did. I am still having some tuning issues with the Pro-Jection... Nothing is easy is it?????
Anyway the exhaust job is nice and it sounds very mello...
Hope this link works..
http://tellico.off-road.com/ubbthreads/showthreaded.php?Cat=&Board=offroadjeepshort&Number=822168&Search=true&Forum=offroadjeepshort&Words=z50k2&Match=Username&Searchpage=0&Limit=25&Old=1month&Main=822168

Ricky...seeya...

Originally posted by 1TonJeep
besides how often do you turn 5000 RPM's?




As often as possible!

On my way to the 6400 limiter :flipoff2:

RickyR, are those the 304 manifolds?
Looks good, clean install. Mine's gonna be fun since my rear 4-link crossmember basically dams up the whole area between the frame rails behind the trans skid.

I'll just echo what someone said about headers: if you get cheap headers with thin flanges, they will leak; If you're willing to spend some money for good headers and install them correctly, they'll be fine. I went with Sandersons (3/8-inch flange, gasketless at the head) with some (expensive) copper collector gaskets and tightened every thing down six times (drive, tighten, drive tighten etc...) and I have zero leakage.

HTH,
Jake

If you insist on headers drop me an email and i will sell you a pair of Hooker Competition inside the frame with copper collector gakets and reducers for $100. They were run for less then 1 hour total.

Mike [/B][/QUOTE]

If you still have tham I know someone who might be interested! Give me a call sometime. 7074798607 Call after 4pm. thanks

Originally posted by Slagburn
RickyR, are those the 304 manifolds?
Looks good, clean install. Mine's gonna be fun since my rear 4-link crossmember basically dams up the whole area between the frame rails behind the trans skid.

Thanks for the compliment...
Yes, 304 manifolds in a 401. The critical thing about the 304 manifolds is the left side for the steering and clutch area. Rear dumps won't work. When you are routing these things just get a little creative and find a good exhaust guy. My system is completely removable with 1/2" and 9/16" wrenches. No cutting here...
Ricky...seeya...

Doug Thorely makes Tri-Y inside-the-frame headers for AMC 304-401 with 3/8 flanges falanges and I think the collector flanges are 3/8 inch also and I think 14-gauge tubing that are nickle plated. IMO opinion these may be the "best" of the AMC/Jeep headers that are not custom made. My son's got them on his CJ-7 and they seem pretty nice. They only thing is that the bottom of the collector is probably about 1/2 to 1 inch below the frame rail. However, as I recall the collector is about where the rear spring hanger is. So that you most likely would hit the spring hanger before the header.

The headers are some of the quietest due to the heavier wall tubing. The nickle plating provides pretty good rust resistance.

I'd ask my son about the dimensions but he is up on the Con now.

Ricky, how much did your exhaust system cost including install?

Just another link for exhaust done like Ricky's. This is definitely for the exhaust pros only though. The guy in this article did mine and it really works well. He's doing my 401 the same way and with 2.5" tubes going into a single 3" the high RPM's shouldn't suffer at all.

http://www.4x4wire.com/tech/josh4x4/exhaust/

Originally posted by Madmarx
Ricky, how much did your exhaust system cost including install?

Thanks for letting me post my 100th post. This should cure my newbie status going on for almost 2 years now......
:D
Anyway, the muffler (Dynomax race style 3" in/out) and collectors and assorted parts were $116 from a buddy that works in a speed shop. The exhaust system labor was $250. Seems like a fair price for a professional install...
Still gotta get the Pro-Jection tweaked...:mad:

Ricky...seeya...