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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: ar3366 on November 09, 2009, 08:41:02 pm

Title: Truck now runs on 6 or 7 cylinders after carb swap
Post by: ar3366 on November 09, 2009, 08:41:02 pm
I have a 79 GMC Sierra.. has a 350 and a quadrajet.. I just took that carb off for a edelbrock 600..since I have made that swap the truck acts like it has a dead cylinder or two. Runs really really ruff... and won't also sustain any real rpm with out chokeing out on fuel or something.. I don't understand if I bought a bad carb.. or did I accidently hurt my engine with I mis adjusted the timeing shortly there after... I'm totally at a loss.. I've tryed just about everything I could think of.. please help
Title: Re: Truck now runs on 6 or 7 cylinders after carb swap
Post by: Captkaos on November 09, 2009, 08:45:49 pm
Was the Edelbrock new?
Was the Q-jet bad?
Have you check the plugs?
Title: Re: Truck now runs on 6 or 7 cylinders after carb swap
Post by: Lt.Del on November 09, 2009, 10:21:20 pm
i wouldn't think you hurt your engine by midadjusting the timing.  Engines are pretty tough.

did you remove any plug wires during this carb change?  You have to rule one thing out at a time.  Ensure plug wires follow the firing order of a small block chevy.

Air/fuel mix correct?  no vacuum leak (carb gasket, hose knocked off)? clogged jet? Cracked distributor cap? Timing correct now? And, what Chris said
Title: Re: Truck now runs on 6 or 7 cylinders after carb swap
Post by: HAULIN IT on November 10, 2009, 09:26:32 pm
Do you have a spreadbore intake? The Edelbrock/AFB may not be sealing on the sides of the back barrels. There is a plate to seal this off...Q-jet gasket on the intake, plate, Edel/AFB gasket, carb. Just a thought, Lorne
Title: Re: Truck now runs on 6 or 7 cylinders after carb swap
Post by: team39763 on November 16, 2009, 11:37:27 am
Did you forget the big vacuum hose?  I did that one time when I swapped my carb and it ran like crap.  It wouldn't idle unless I revved it, it ran like crap.  Took me a few days to figure it out.
Title: Re: Truck now runs on 6 or 7 cylinders after carb swap
Post by: joesgarage71 on November 16, 2009, 04:12:10 pm
 Sounds like something real simple, check your work
Title: Re: Truck now runs on 6 or 7 cylinders after carb swap
Post by: thirsty on November 16, 2009, 05:56:04 pm
pull your plugs and see whats going on.
Title: Re: Truck now runs on 6 or 7 cylinders after carb swap
Post by: VileZambonie on November 16, 2009, 06:21:04 pm
Quote from: team39763 on November 16, 2009, 11:37:27 am
Did you forget the big vacuum hose?  I did that one time when I swapped my carb and it ran like crap.  It wouldn't idle unless I revved it, it ran like crap.  Took me a few days to figure it out.

This is most likely what he did.