69 with Catco cats ?
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,720
Likes: 19
From: Manhattan Beach Ca
69 with Catco cats ?
I'm thinking of putting some high flow cats on my exhaust to try and reduce the heavy rich stinky exhaust smell I have and need any advice.
My car is smog exempt with true duals and flow 40s right now.
I dont know anything about cats and wonder if they would even affect the output at all?
My car is smog exempt with true duals and flow 40s right now.
I dont know anything about cats and wonder if they would even affect the output at all?
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
Cats only work at lambda 0.96-1.04. That's an air/fuel ratio of 14.1:1 to 15.3:1. It is unlikely you will be able to run in that range with a carb, especially if you have any aftermarket parts (carb, cam).
Another problem I see is the fiberglass floor. Cats get very hot and the factory went to a metal floor because of it. Atleast you'd need a good big heatshield.
Question is why is you exhaust so stinky? Some careful tuning should get rid of most of it. The smell is hydrocarbons as carbon monoxide doesn't smell. Hydrocarbons are unburned fuel. Find out why it isn't burning the fuel and the smell goes away. Maybe bad ignition? Timing advance? Rich carb?
Another problem I see is the fiberglass floor. Cats get very hot and the factory went to a metal floor because of it. Atleast you'd need a good big heatshield.
Question is why is you exhaust so stinky? Some careful tuning should get rid of most of it. The smell is hydrocarbons as carbon monoxide doesn't smell. Hydrocarbons are unburned fuel. Find out why it isn't burning the fuel and the smell goes away. Maybe bad ignition? Timing advance? Rich carb?
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,720
Likes: 19
From: Manhattan Beach Ca
Zwede, I've been trying to solve that for a long time without success. Plugs look perfect to lean. Car runs fast and perfect. Carb is Qjet jetted not too rich. So it's hard to pinpoint.
Looks like from your statement they wouldnt work since I'm probably below 14:1.
Looks like from your statement they wouldnt work since I'm probably below 14:1.
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
If the plugs look lean you may be lean enough to where a cat will do some good. I don't think you'll get very long life out of it though. The factory had some success with cats and carbs in the 70's although it never worked real well. My biggest worry would be the fiberglass floor and the massive heat a cat makes.
You may want to look into a wideband O2 meter. You can get one without a gauge that graphs to a laptop for under $200 incl sensor (innovate LC1). Even though the plugs are not sooty you may be rich.
You may want to look into a wideband O2 meter. You can get one without a gauge that graphs to a laptop for under $200 incl sensor (innovate LC1). Even though the plugs are not sooty you may be rich.
