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Old 02-11-2016, 05:00 PM   #34
BigRed76
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Join Date: Jan 2010
Location: Loveland, CO
Posts: 1,921
Re: Mufflers VS Catalytic converters

Quote:
Originally Posted by davepl View Post
Not actually. I have all three:

- Carb'd car with a cat ('75 Monte factory)
- Carb'd truck with no cat ('70 GMC)
- EFI car with no cat ('69 Camaro ZZ502 BS3 Sequential EFI)

The EFI car still smells like raw gas. It runs at about 14.6:1, but to get near stoich at idle with a cam in a motor like these requires a lot of extra fuel that winds up getting in your girlfriend's hair.

Now a poorly tuned car with cats will stink like sulfur dioxide, so there's no substitute for properly tuning the thing. But properly tuned, cats get rid of the raw fuel smell.

Maybe if gasoline still smelled like it did in 1970 I'd be OK with it, but it doesn't.
I guess I was a bit vague with that statement, since my vehicles are a bit different. What I had in mind was my 5.3 with no cats in my '71, but comparing that to your ZZ502 we are worlds apart
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Zach

1970 Chevrolet Custom Camper K20
1971 GMC Super K2500, 12V/NV4500 swap in progress
1971 Chevrolet Custom C10
1972 Chevrolet Custom Deluxe C20, 5.3/4L60E
1972 Oldsmobile Cutlass Supreme, 455/TH400, 3.73 posi
2004 GMC Sierra 2500HD, LB7/Allison, CCSB
2005 GMC Sierra 1500, 5.3/4L60E, CCSB

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