U can see in my sig what I'm working with. I have no cats. The exhaust smell is well in a word , cough cough cough... do I need a cat?

The exhaust is hooker shorty, 3in collectors into 2.5 y pipe, to single pipe to v force muffler to dual stainless steel pipe tips

Oh, no emissions test

 

That would definitely cause an exhaust smell. You don't smell the exhaust when you are in the car, do you?

 

Check the charcoal canister. I have no cat and thought that was my problem also and it wound up being that charcoal canister. I don't run cats on ANY of my rides and have always taken them off even on my newer dailys and I do not have trouble with any gassy smell.

 

Thk u

 

A lack of cat will make fuel smells when you are stationary or behind a running car. Anyone who tells you otherwise has been breathing too much carbon monoxide.

 

I'm not running cats either and do notice stronger than normal fumes but mostly in the garage on startup when the tune is rich. Once she warm up she leans out and fumes are no where as bad. Have you checked for header leaks? I had a leak where the collector meets the pipe on the passenger side. You couldn't drive the car without smelling like the inside of a gas can.

 

hahahahahaha lol.... I'll check it out by this weekend. I gotta get this car squared away before I start on the 6.0... thx fellas

 

Wow I must be breathing too much carbon monoxide. I haven't had a problem with exhaust smell in probably a dozen cars and trucks ive had with no cats. A leaky donut gasket and a charcoal canister were the culprits both times I noticed a scent.

 

Cars didn't have cats for A LONG TIME, and it wasn't ever a problem for any (or at least most) individual cars until people decided to "improve" them on their own.

In fact, quite to the contrary... when cats first appeared on 49-state cars (I wasn't living in California at the time) in the early 70s, THOSE were the ones that had the funny-smelling exhaust. You could smell em long after they had disappeared down the street.

I'd suggest starting out with making sure there are no leeeeeks. It doesn't take much, in the right place, to put exh gas where it can get sucked into the car by normal pass cabin venting. I'd also suggest making sure there are no leeeeeks in the car body itself, mostly toward the rear, like around the spare tire well, cargo hold, "glove box", wheel wells, back glass seal, etc. All of those areas can allow exh even from a completely functional exh system to be drawn into the car.

If you have "breathers", GET RID OF that, and put a functional, closed, properly set-up PCV system back on it. Crankcase vapors have a pretty hideous smell on their own.

This all is of course separate from fuel vapor aroma, such as canister issues.

Then, if the problem is more that the exh itself just smells rank to begin with, work on the tune. It's probably rich. A typical out-of-the-box Holley tune is NOTORIOUS for this. See the Holley Tuning sticky on the carb board.

 

Yep ^
Needs PCV
Needs a SEALED crankcase (pressure tested)
Needs a SEALED exhaust system and intake air path (pressure tested)
Need to run the exhaust all the way back (like a regular car)
Needs a modern combustion engine (after 2001~ is preferable, the older the engine gets the less technology in the combustion chamber/piston design, the less efficient combustion, the more leftover emissions "in theory")
Needs a good tune (should idle 14.7 to 15:1 usually for ideal 'smell')

 

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