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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 75 C20 on December 06, 2006, 08:29:00 pm

Title: carb idling
Post by: 75 C20 on December 06, 2006, 08:29:00 pm: hey everyone- i got a 75 c 20 with a 350, i was palyin with my carb tonight that i put on probly a yr ago now- its a edelbrock 600cfm profromer series. anyhow i was adjusting the idle down- it was bout 800 rpm and i took the ideal screw out as far as it will adjust and it wont go below 700 rpm- how do i get it to idle at about 500 or so

thanks
Title: Re: carb idling
Post by: Lt.Del on December 06, 2006, 10:11:00 pm: That could be a number of problems:

Timing may be off. Try advancing the timing (turning distributor counter clockwise.) Actually, retarding the dist may decrease rpms as well.

Vacuum leak may be a culprit. If you have a vacuum leak, you'll never get it to idle smoothly low rpms. Take some wd40 while engine is idling and spray around vacuum lines/hoses and gaskets. If rpms go up, you found a vacuum leak.

Carb air/fuel mixture may need to be adjusted as well.

That'll get ya pointed in some directions.

SgtDel
aka "Andy"

www.delbridge.net

1979 Big 10 383 stroker
1991 Blu 'Burb 3/4 ton 4x4
Title: Re: carb idling
Post by: VileZambonie on December 07, 2006, 05:53:00 pm: It sounds like you might be stuck on the fast idle cam. Make sure the screw for the fast idle cam is backed out. On the AFB's I believe it's facing down toward the intake.
Title: carb idling
Post by: markzepp820 on December 25, 2006, 04:41:00 am: off the subject...does your truck run good with that edelbrock performer? They have mechanical secondaries and I'm guessing you have a Automatic(TH400?) I hear carbs with mechanical secondaries don't perform as well on heavier vehicles with automatics.
Title: carb idling
Post by: usmcchevy on December 25, 2006, 09:40:00 am: he has a mucnie sm465 granny 4 speed
Title: Re: carb idling
Post by: 75 C20 on December 25, 2006, 06:40:00 pm: yeah i got a granny 4 speed as usmcchevy said but yeah it runs awesome
i love it- for being pretty well stock it rocks
Title: Re: carb idling
Post by: MY854X4 on December 28, 2006, 12:37:00 am: So did this work? If so how do I adjust mine I have that exact problem.
Title: Re: carb idling
Post by: 75 C20 on December 28, 2006, 05:13:00 pm: Quote:
So did this work? If so how do I adjust mine I have that exact problem.

yeah it worked
i went to the idle screws on the front of ur carb- first i marked where they were so if got worse i could at least put it back to where it was- i turned each of them the smae amount ang got it down to where i wanted it and with a little more playing u can git it to idle just how u want it
Title: reply
Post by: MY854X4 on December 29, 2006, 04:03:00 pm: You mean the two screw's on the front bottom of the carb when you say idle screw's right?
Title: yep
Post by: 75 C20 on December 29, 2006, 05:40:00 pm: yep those are the 2 screws im talkin bout- if u still have ur owners manual it should tell u how to do it in a lil more detail
Title: Re: yep
Post by: VileZambonie on December 29, 2006, 07:59:00 pm: Those two screws are your idle mixture screws. Basically screw them all the way in and back out about 3.5 turns each and adjust accordingly from there.
Title: repley
Post by: MY854X4 on December 29, 2006, 09:20:00 pm: And what about the screw on the throttle linkage that I think control's when the second set of barrels open's. What's the stock setting on that?