changing air/fuel mixture - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ZombieWeinerDog · 05-27-2009, 09:48 PM

how can i do this correctly without a air/fuel gauge. i think it is running a little rich, but i dont want to kill the engine

ZombieWeinerDog · 05-28-2009, 12:15 AM

nobody?

**WorkinLonghorn** · 05-28-2009, 12:53 AM

What evidence of a rich mixture do you see?
If your plugs look good,no soot, and you don't see black smoke out the back,then I wouldn't bother with it.
How does it run?

ZombieWeinerDog · 05-28-2009, 01:19 AM

well, its a little sluggish when the peddle is all the way down, but if i lift it up slightly, it accelerates faster

**mr48chev** · 05-28-2009, 01:50 AM

I think it is too lean rather than too rich.

That 600 cfm carb is a bit to the small side for the best performance out of a 350. That may not be the issue of the moment though.

One thing to check is your complete fuel line/system for a restriction.
Make sure that there no kinks or twists in the fuel lines.
Make sure that the rubber lines aren't kinked.
If any brass fittings in the lines have been replaced make sure that the orfices in the fittings are full size and not reduced in size.
about 35 years ago I bought a 57 Chev Panel truck in Texas with a killer 327 in it. It had one of those early Corvette dual 4 intakes with the little carters. Anyhow it would go like gangbusters for about 100 ft and then fall on it's face. If I let of the gas and kicked it again and shifted it would pull hard for about the same distance again.
After checking everything we found out that it had a natural gas fitting in the fuel line with an orfice about 1/8 or less in diameter.

There should be plenty of "how to get performance out of your Performer carb" books around and I would start by picking up one of those and finding out what it takes to fine tune the carb.

Amazon.com: How to Rebuild and Modify...
The bottom part of the link works
You might find one at Borders, Hastings or Barnes & Noble too. Or Schucks or other parts houses that keep a few car how to books around.

05-27-2009, 09:48 PM	#1
ZombieWeinerDog Registered User Join Date: Oct 2008 Location: Sparta, MI Posts: 446	changing air/fuel mixture how can i do this correctly without a air/fuel gauge. i think it is running a little rich, but i dont want to kill the engine __________________ 1972 longbed- 454 1967 shortbed- 355

05-28-2009, 12:15 AM	#2
ZombieWeinerDog Registered User Join Date: Oct 2008 Location: Sparta, MI Posts: 446	Re: changing air/fuel mixture nobody? __________________ 1972 longbed- 454 1967 shortbed- 355

05-28-2009, 12:53 AM	#3
WorkinLonghorn Senior Member Join Date: Dec 2006 Location: Studio City, Calif. Posts: 2,883	Re: changing air/fuel mixture What evidence of a rich mixture do you see? If your plugs look good,no soot, and you don't see black smoke out the back,then I wouldn't bother with it. How does it run? __________________ '69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme.

05-28-2009, 01:19 AM	#4
ZombieWeinerDog Registered User Join Date: Oct 2008 Location: Sparta, MI Posts: 446	Re: changing air/fuel mixture well, its a little sluggish when the peddle is all the way down, but if i lift it up slightly, it accelerates faster __________________ 1972 longbed- 454 1967 shortbed- 355

05-28-2009, 01:50 AM	#5
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,640	Re: changing air/fuel mixture I think it is too lean rather than too rich. That 600 cfm carb is a bit to the small side for the best performance out of a 350. That may not be the issue of the moment though. One thing to check is your complete fuel line/system for a restriction. Make sure that there no kinks or twists in the fuel lines. Make sure that the rubber lines aren't kinked. If any brass fittings in the lines have been replaced make sure that the orfices in the fittings are full size and not reduced in size. about 35 years ago I bought a 57 Chev Panel truck in Texas with a killer 327 in it. It had one of those early Corvette dual 4 intakes with the little carters. Anyhow it would go like gangbusters for about 100 ft and then fall on it's face. If I let of the gas and kicked it again and shifted it would pull hard for about the same distance again. After checking everything we found out that it had a natural gas fitting in the fuel line with an orfice about 1/8 or less in diameter. There should be plenty of "how to get performance out of your Performer carb" books around and I would start by picking up one of those and finding out what it takes to fine tune the carb. Amazon.com: How to Rebuild and Modify... The bottom part of the link works You might find one at Borders, Hastings or Barnes & Noble too. Or Schucks or other parts houses that keep a few car how to books around. Last edited by mr48chev; 05-28-2009 at 01:52 AM.



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.