Engine Exhaust Fumes on a Ford 302 V8

[CJJP1984]

New jeep owner...this is all probably gonna sound dumb.....
getting a lot of fumes inside the jeep and it's excessively loud. Pipe end just in front of the rear tires. Wondering if a new exhaust system that converts to a single pipe will fix the noise/fumes; if that is even possible?
Previous owner used the jeep for mud bog racing, needless to say I don't need anything this powerful, so also wondering if it's just better to swap the v8 out for an I6. transmission was converted from auto to manual at some point, so not sure that makes a difference either....

 

[CJ]

For the exhaust dumping before the back tires almost always sucks fumes into the cab. The best is to dump out the back corners behind the wheels.

 

[petemcl]

New jeep owner...this is all probably gonna sound dumb.....
getting a lot of fumes inside the jeep and it's excessively loud. Pipe end just in front of the rear tires. Wondering if a new exhaust system that converts to a single pipe will fix the noise/fumes; if that is even possible?
Previous owner used the jeep for mud bog racing, needless to say I don't need anything this powerful, so also wondering if it's just better to swap the v8 out for an I6. transmission was converted from auto to manual at some point, so not sure that makes a difference either....

The exhaust exiting the side of the vehicle is always a problem. I believe that it is no longer allowed on new cars. The other issue is the state of tune of the engine. Many people put too big a carburetor on their engines. Holley says that it is the biggest mistake made by most people. They actually have a carb selector on their website: Holley Carb Selector
I'm not sure what mods were made to your CJ to fit a Ford 302 but CJ's with stock 304 V-8 engines had the exhaust exit BEHIND the rear wheels. If you try to go out the back like many hot rods you can degrade your angle of departure which can be bad when you need to back up off road. The state of tune of your engine will significantly imact your exhaust odor. A properly tuned engine has little unburned fuel odor. It also will perform best and use the least amount of fuel. If you know someone with a Sun infrared exhaust gas analyzer you can quickly set up you engine so that it runs its best.

 

[TSB8C]

Echoing the prior comments about exhaust exiting under the door openings or just in front of the rear tires. I had a SBC engine with headers that exited through the front fender wells, then a set of "Purple Hornies" mufflers right under the door openings and stopping in front of the back tires. Loud as he!! and fumes entered the cab when stopped or driving slowly. Easy install to be sure because you're not routing pipes underneath and having to dodge stuff. But when I installed the new Crate motor, I kept a true dual exhaust (no cross over or anything) but ran two pipes clear out the back and exiting at the two rear corners. Still a bit loud, but far less so in the seats and no fumes in the cab. Here are two pics: (1) shows a prior CJ5 I sold that had the fender well headers and "Purple Honies" mufflers (they're black under the side steps) and my current rig showing where the exhaust exits at the rear (pic shows one side, but same on both rear corners).

 

[CJJP1984]

The exhaust exiting the side of the vehicle is always a problem. I believe that it is no longer allowed on new cars. The other issue is the state of tune of the engine. Many people put too big a carburetor on their engines. Holley says that it is the biggest mistake made by most people. They actually have a carb selector on their website: Holley Carb Selector
I'm not sure what mods were made to your CJ to fit a Ford 302 but CJ's with stock 304 V-8 engines had the exhaust exit BEHIND the rear wheels. If you try to go out the back like many hot rods you can degrade your angle of departure which can be bad when you need to back up off road. The state of tune of your engine will significantly imact your exhaust odor. A properly tuned engine has little unburned fuel odor. It also will perform best and use the least amount of fuel. If you know someone with a Sun infrared exhaust gas analyzer you can quickly set up you engine so that it runs its best.

Thanks for the info. Probably not doing too much offroading and it's got at least a 4 inch lift on it, so I'm thinking the re-routing out the back shouldn't be too big of a problem.

 

[cglax6]

When you reroute that exhaust, be sure to angle it at about a 45 degree behind the rear tire. If you send it straight out the back, fumes will get sucked in through the back. You don't have to worry about this is you always have a hard top on, or always have all the windows closed on a soft top.

 

[007]

When you reroute that exhaust, be sure to angle it at about a 45 degree behind the rear tire. If you send it straight out the back, fumes will get sucked in through the back. You don't have to worry about this is you always have a hard top on, or always have all the windows closed on a soft top.

Agreed…45 down and 45 out centered on rear wheel. Zero fumes.


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