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chicklin · 12-01-2009, 07:14 PM

Did some more tinkering today. Finally figured up the MPG for this thing: 8.6 mpg. Not good. I also noticed that I can get it to pop and blow out a plume of black smoke while in park after it's good and warm.

So, obviously, I am getting a bunch of unburnt fuel in the exhaust due to it running rich (at least that seems right to me). So, where do I start troubleshooting this? I have a brand new rebuilt carb that I ordered online, but I guess I really have no idea how it is adjusted. Like I mentioned, the idle screws are about 3 turns out, but that should have very little to do with the mileage driving back and forth to work on the interstate, right?

Is there some way to adjust the other jets in this carb? Or, is there something else causing the rich condition? It's a stock Quadrajet M4MED.

12-01-2009, 07:14 PM	#8
chicklin Registered User Join Date: Jun 2008 Location: Kansas City, MO Posts: 108	Re: Exhaust popping Did some more tinkering today. Finally figured up the MPG for this thing: 8.6 mpg. Not good. I also noticed that I can get it to pop and blow out a plume of black smoke while in park after it's good and warm. So, obviously, I am getting a bunch of unburnt fuel in the exhaust due to it running rich (at least that seems right to me). So, where do I start troubleshooting this? I have a brand new rebuilt carb that I ordered online, but I guess I really have no idea how it is adjusted. Like I mentioned, the idle screws are about 3 turns out, but that should have very little to do with the mileage driving back and forth to work on the interstate, right? Is there some way to adjust the other jets in this carb? Or, is there something else causing the rich condition? It's a stock Quadrajet M4MED. __________________ 1954 Chevy 3600 - 235, 4-spd 1986 Chevy Suburban - 350, 700R4 Last edited by chicklin; 12-01-2009 at 08:09 PM.