exhaust for amc 401 in CJ7

grignac48

I am finally working on a solution for exhaust. I looked at headers and liked the idea of the exhaust manifold. I got a pair of exhaust manifolds and now am trying to get the rest of the exhaust. The mainfolds are used, I saw where someone mentioned that the older ones come down mid rather than at the back. What do I ask for at the parts store to get a new cross over that is correct. I chose a 79 cj with a 304 but the flanges are 3 1/2" instead of the manifold 3" bolt spacing? I would do headers but don't want over the frame and would like the exhaust to be behind me so I can hear. What about a CAT or how did you space passed it. All comments welcome :-|

1tuffcj

i'm confused, if you already have the exaust manifold, all that's left is some pipe and cat if you realy want one. (the cat that is) take it to a muffler guy or buy some pieces and make it your self.

1tuffcj

one more thing i just read your post again, if you want to run headers. just get some block hugger's, they run on the inside of the frame. then just run it out the back. i don't think you can go to a parts store and ask for stock exaust pipe ( the cj's that is):-| or maybe you can :shock: i don't know iv'e always just ran my exaust where i want. good luck p.s. i ran mine out the side, a little to tight for my liken, i have a cj5 with a 401 and i also put a 727 t/f tranny in it. i would think a 7 would be no problem ( infame that is).

tufcj

The problem I had with the stock crossover (Y-pipe) was that with the lift I run, about 7", that the front shaft wouldn't clear the pipe. I also smashed it flat because it hangs lower than the skid.

On my CJ, I had a full custom exhaust made. The passenger side loops about 135 degrees and faces forward, then crosses under the front of the oil pan. It then turns toward the rear and joins with the drivers side, all this is 2 1/4" pipe. From the joint, it's 3" out the back with a free flow cat and a Magnaflow welded muffler. The entire system is no lower than the frame rail, except right where it dumps behind the rear wheel.

Bob
tufcj

ironman_gq

I have in fram headers and dual 2.25 exhaust with glasspack mufflers. it was very cheap and sounds pretty decent and also doesnt hang lower than the frame. Get in frame headers from 4wd.com and bring it to a muffler shop.

JERSEYJOE

I have run into this same dilema. On my 81 I have a stock y pipe that was reproduced by Classic Exhaust in Ohio. I had it Jet Hot coated so it will last forever. This will work with up to 3 inches of lift after that the front drive shaft will hit. For my current Porject I am using Edelbrock Shorties with custom made head pipes. I am planning on ditching the Cats, running a balance tube ( IMPORTANT) and mufflers with down spouts. I am not planning on running tail pipes. Since I have the 2 front pipes mocked up, I would be happy to have my pipe guy bend up a couple of extras these will allow you to fab the rest of the system as you liked. the hardest pipe is the left side front pipe.

1980_Cj7

Here's what we did (pics under post by rwsr50).

We couldn't run true duals because the anti-wrap bar was in the way on the passenger side. I understand it's actually better to have two into one, or at least an "X" pipe anyhow.

We crossed over above the t-case, but we have a 3" body lift. Don't know if it would be possible without that. Sounds and runs great. 2 1/2" going into muffler, 3" coming out.

Our exhaust guy told us that regular engine enamel in cast iron gray color would hold up on the exhaust manifolds, so we figured he knew what he was talking about. WRONG! It immediatey turned PINK! Later redid the exhaust manifolds with POR exhaust paint in cast iron gray color, and it's holding up great.

We originally wanted to run in-frame headers, but the passenger side collector ended up right on top of and against the front driveshaft, so we couldn't use them. Guess you would need shorties or something.

grignac48

Thanks for all of the input. I found out the factory crossover does not work with the lift I have. I guess I need to decide headers over exhaust manifolds and then take it to a custom exhaust shop. Or get creative with some Pipe and welding. You guys are a great source for information :t:

tufcj

I only went to factory manifolds because I had to pass emissions, and the AIR pump and rails had to be there. I went from fenderwell headers and turbo mufflers and only feel a slight drop in performance at the very top end (around 4500 RPM), but how often does it rev that high when rock crawling? The downside of fenderwell headers is that the collectors rust, since they "collect" all the road debris and water from the front tires. The mufflers hanging under the body outside the frame also tend to get ripped off, I smashed/tore several. I've probably saved enough in rusted/broken parts to pay for the system. Bob tufcj

1980_Cj7

I luv the looks and sound of the fenderwell headers and sidepipes, but, didn't go that route for all the exact same reasons tufcj listed above, since our Jeep does big rocks.

46flattie

I tried to keep my CJ a little quieter than previously run fender well exit headers and "torque tube" mufflers. (So I could drive it for a few hundred miles at a time w/o ear plugs...) What I have now sounds great and is not too obnoxious. I'm running Edelbrock shorty headers w/2.25" pipe back into a Series 50 Flowmaster muffler w/two 2.25" inlets and one 3" outlet. Therefore, no low hanging crossover in front of the skid plate and a clean single 3" out towards the back. Sounds good and throaty behind the 401! Unfortunately, I no longer have the part number for the muffler, but it seems like it was for a Chevy truck application. And no I'm not running the muffler backwards! It's meant for this configuration. Fits great under an 8 and the shop I had bend it does put them in 7's too, but it's a little tighter.

mycj7

For my dual exhaust, I run the stock exhaust manifolds with no crossover pipe into dual resonators (nice and round, small with no edges to get caught on stuff), and 2 tailpipes with turndowns. Run a 727 and the exhaust is tight, but fits, and is above the framerail. I would however like to have a crossover pipe, but it doesn't look viable. On a side note, what are y'all running for muflers. My resonators are a bit loud, and I think I may want to tone it down a bit. :)

1980_Cj7

46flattie wrote
I tried to keep my CJ a little quieter than previously run fender well exit headers and "torque tube" mufflers. (So I could drive it for a few hundred miles at a time w/o ear plugs...)

What I have now sounds great and is not too obnoxious.

I'm running Edelbrock shorty headers w/2.25" pipe back into a Series 50 Flowmaster muffler w/two 2.25" inlets and one 3" outlet. Therefore, no low hanging crossover in front of the skid plate and a clean single 3" out towards the back. Sounds good and throaty behind the 401!

Unfortunately, I no longer have the part number for the muffler, but it seems like it was for a Chevy truck application. And no I'm not running the muffler backwards! It's meant for this configuration.

Fits great under an 8 and the shop I had bend it does put them in 7's too, but it's a little tighter.

Where are you crossing over and going two into one???

46flattie

<t>[quote="1980_Cj7

Where are you crossing over and going two into one???

At/in the muffler. This muffler is set up for (2) 2.25" pipes in and (1) 3" out. I have one 2.25" that comes relatively straight back from the driver side header into the muffler. The passenger side header to muffler pipe runs along the T-case above the skid plate and crosses up/over the rear driveshaft just behind the T-case output and then 90's into the 2nd 2.25" inlet of the muffler. Out the back of the muffler w/3". The muffler is hung under the driver side near the stock 6 cyl location.

Scott</t>