Anyone with experiance using cats on a motor with a large cam

496BBC

496BBC

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Deep in the marsh, South Louisiana
Thinking of installing cats to reduce exhaust smell, wife don't care for the smell.

I'm running a large solid roller cam and I have side pipes so the exhaust is right at the windows.

Just wondering if anyone here has tried this and how did it work for you.

Neal
 
496BBC said:
Thinking of installing cats to reduce exhaust smell, wife don't care for the smell.

I'm running a large solid roller cam and I have side pipes so the exhaust is right at the windows.

Just wondering if anyone here has tried this and how did it work for you.

Neal
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If it is running that rich cats would probably plug up anyways.
 
If the cats a hot enough, you'll get a rotten egg smell. What's the smell you get now? Rich exhaust? If the idle is rich you may need to lean it down there while leaving it fat enough on top.
I'll bet you've already been thru the power valve and stuff like that.

I had a similar deal with Ol' Red. Burn your eyes at idle in the garage. Put the Demon carb on with the idle compensator, and no more stink. Drilled the throttle plates on a Holley about 215 years ago for the same effect.
 
TimAT said:
If the cats a hot enough, you'll get a rotten egg smell. What's the smell you get now? Rich exhaust? If the idle is rich you may need to lean it down there while leaving it fat enough on top.
I'll bet you've already been thru the power valve and stuff like that.

I had a similar deal with Ol' Red. Burn your eyes at idle in the garage. Put the Demon carb on with the idle compensator, and no more stink. Drilled the throttle plates on a Holley about 215 years ago for the same effect.
Click to expand...

wow 215 years ago ....
 
Spoke with MagnaFlow about there round cats,

Tech said he had no experience with this and that the cat would more than likely foul. He suggested using their ceramic cat it would last longer than the cat containing the metal core.

With the overlap it's got to be rich, the exhaust does not have a gas smell; it will burn your eyes while idling in the shop and leave your clothes smelling like the exhaust.

I've spent a tremendous amount of time tuning the carb with a wide band meter (LM1). I've spent allot of time talking with people that know more about carbs than I will ever learn. Most say that with a cam with a good bit or overlap the exhaust will smell.

I played with the timing today and set the idle mixture to 14:1 and it has gotten allot better than it has been for a while. The timing made the biggest change, it was at 35* locked out. I moved the curve to 15* at idle and 35* in by 3000 rpm. The smell at idle has gotten better now.

I couldn't do this in the past due to temp control issues but I have full control of the temps now so I'm able to reduce the idle timing.

Neal
 
QUOTE=JeffP1167;76733]Put some diesel stacks on it, exhaust about 4 feet above the roof of the car. .... end of problem.[/QUOTE]

That's what I have running along the side of the car already, maybe I can add some extensions

Neal :bounce:
 
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