Another swap header question.

[350CJ7]

First time poster here. I would like to start off by saying thanks to everyone who contributes here. There is so much invaluable info available.
Now here's my question. I'm in the process of swapping in a sbc 350/sm465-Dana 300 setup into a 86 CJ7 . It's not gonna be a quick project for sure. Now I'm at the point of buying headers. It appears from researching that block hugger type headers are ideal for in frame exhaust. But I haven't read about using short rear dump headers. I haven't been able to see any pictures of using this type. Mostly because of the Photobucket images can't be seen. Any pros or cons of rear dump headers, pic's? I'm using Transmission dapt weld in motor mounts if that helps. Thanks again.

 

[RiverandSand]

Welcome, I am fairly new also. This site is a wealth of knowledge, best CJ site I have found.
I have the same setup, but a 305. I do have a ZZ4 350 crate motor waiting to go in this summer. I currently have the rams horn exhaust manifolds and are center dump and clears all the critical parts. I also will be installing the block hugger headers with the new motor, the only issue I may have is the left motor mount bolt. There are rear dump headers Headman and Thorely makes them, but the reviews haven't been the best. You can check them out at summit racing, by typing in jeep cj coversion headers. Novac also makes a set but are really pricey. I really like the sbc in the CJ its alot of fun to drive.

 

[350CJ7]

Thanks for the info. I wasn't looking so much at the swap headers as just a rear dump short header. I thought about the ram horn type manifolds. For ease of fitment and plug access. Not sure if they would hurt performance of my motor. It's built with aftermarket 2.02 vortec heads and comp xr276hr cam, airgap intake with flattop pistons @ 10.1 to 1. Can't wait to get it going. Just a weekend cruiser around town.

 

[RiverandSand]

The problem with the shorty rear dump is clearance issues with rightside starter and front driveline. Leftside is fairly clear though. Then there is the fenderwell headers, but I really don't that look unless it's a gasser. Inside the frame is a much better look IMHO. Are your heads D port exhausts? If so that limits the options too. You correct about power limts on the rams horn, but I have run across proformance style ram horns, but can't remember who produced them.

 

[350CJ7]

Thanks for the info on the rear dump headers. That's what I've been trying to find out. As far as the exhaust port shape. They are based off of the 906 castings. They measure roughly 1.300x1.300 with radiused corners. I imagine a 1 5/8" primary would work?

 

[RiverandSand]

Sounds like you won''t have any problems with finding headers with that port configuration. Speedway motors has good prices on block huggers.
Unfortunately I have the D ports which limits the options, but the guy I got the motor from already had D port block huggers with it. Just need to get them heat coated.

 

[Manic Mechanic]

There isn't much if anything to be gained on the street (below 5,100 RPM) by using tubular headers. A friend put his new 383 on the dyno and tried both shortly headers and two and a half inch (high performance and Corvette manifolds) Ram's Horn style on his engine.and there was not much to be gained (five to seven horsepower), money to be lost and the joys of exhaust leaks abound with tubular headers. Above 5,100 the stock exhaust is done and tubular headers rapidly pull away from the stock exhaust in power. If you have a tach you know where your motor spends it's life while cruising on the street. It is generally below 2,400 RPM. unless you have a fairly steep rear gear ratio.

 

[350CJ7]

Appreciate all the info. I guess I'm going to give the block huggers a try. Here's what I have in mind for the rest of the exhaust system. Passenger side over to the driver's side Y'd into one. Would like to have the system as short as possible with 45° or 90° on the muffler outlet. Thinking a chamber type muffler. Any suggestions or ideas?

 

[RiverandSand]

That is how mine is currently setup, with the tailpipe exiting behind the left rear wheel.
The air flow around these jeeps is a little different because the jeep is so open, exhaust fumes can enter the cabin very easy. The best place to end the tailpipe seems to be either left or right rear corners of the jeep.

 

[350CJ7]

FWIW I ordered a set of stainless headers off Amazon. Firstly I took a magnet to them the tubes were nonmagnetic. However the flange were. Welds look good and the flanges are 3/8" thick. They bolted right up and fit with the motor mounts. I didn't have a set of plugs to check the clearance. I'll update when I get the motor in for any clearance issues.

 

[007]

I'm not a header fan, but I strongly suggest wrapping these to insulate them, keeps the heat going out with the exhaust.

Lastly, as for the tips, 45 out and 45 down behind rear wheel. Fumes are drafted by the rear tire and diffused in that turbulence. Almost completely removes the issue of fumes for driver/passenger.