Carb adj. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**53burb** · 01-19-2006, 02:15 AM

I was messing with the A/F adjustment earlier. I have an 1806 Edelbrock (same as 1406 with Adjustable Valve Secondaries & 650CFM). If I turn the A/F screws in all the way, there is little or no change in idle at all. This is with both screws turned all the way in. I adjusted the floats, but no change. I yanked out the #1 cylinder spark plug a couple of weeks ago to set the engine at TDC to adjust the valves, and it wasn't fouled or looked like excessive fuel at all. I guess what I am asking is: Do I need a fuel regulator?? BTW it is a 350 with a recently replaced fuel pump...

**53burb** · 01-20-2006, 10:32 AM

ttt

Solver · 01-20-2006, 12:12 PM

Sounds like a vacuum leak to me . should idle poorly with screws all the way in. try spraying some carb cleaner around the base of carb while truck is running and see if the engine speed changes. if the speed changes you have found your leak

**53burb** · 01-20-2006, 04:32 PM

Thanks, I will try it this weekend. Anybody else have anything???

Sonny's at Work · 01-20-2006, 04:35 PM

WD-40 is a little safer....

MrC1 · 01-20-2006, 05:26 PM

You didn't mention if this was a typical truck engine or if you've cammed it up. By chance you've got a big cam and a fairly wild idle, it's possible that you'll have to revert to the old "drill a hole in the throttle plates" trick. This allows the engine to have enough air to idle correctly while not opening the throttle blades too much, which bypasses the idle circuit.

If you've got a mild engine, just ignore everything I just said, er typed.

**53burb** · 01-20-2006, 06:23 PM

The engine has a 268 Competition Cam in it. I don't know all the specs on it other than it has .454 lift on intake & exhaust on it, Edelbrock Performer 2101 manifold, HEI, & dual ramhorn exhaust with glasspacks. It idles fine, only the idle doesn't change when both screws are turned all the way in.

01-20-2006, 10:32 AM	#2
53burb Senior Member Join Date: May 2004 Location: Queen Creek, AZ Posts: 1,005	Re: Carb adj. ttt

01-20-2006, 12:12 PM	#3
Solver Registered User Join Date: May 2000 Location: Storm Lake, Ia Posts: 1,449	Re: Carb adj. Sounds like a vacuum leak to me . should idle poorly with screws all the way in. try spraying some carb cleaner around the base of carb while truck is running and see if the engine speed changes. if the speed changes you have found your leak __________________ 1972 Cheyenne Super 20 LWB-Blue 1972 Cheyenne Super 10 LWB-Black 1972 Cheyenne Super 10 LWB-Red 1972 Cheyenne Super 10 LWB-green 1972 GMC 4x4 LWB-White 1971 Cheyenne 10 LWB-Ochre 1971 Cheyenne 20 Longhorn-Copper 1971 Cheyenne 20 Longhorn-Black 1969 Custom 10 LWB-lt blue 1968 GMC 3/4 ton-green 1968 1/2 ton swb stepside-silver 1967 Chevrolet CST 10 LWB-green 1967 Chevrolet custom 20 LWB-Maroon

01-20-2006, 04:32 PM	#4
53burb Senior Member Join Date: May 2004 Location: Queen Creek, AZ Posts: 1,005	Re: Carb adj. Thanks, I will try it this weekend. Anybody else have anything???

01-20-2006, 04:35 PM	#5
Sonny's at Work Registered User Join Date: Jan 2006 Location: Centerville, GA Posts: 16	Re: Carb adj. WD-40 is a little safer....

01-20-2006, 05:26 PM	#6
MrC1 Dork For Days Join Date: Aug 2005 Location: Dallas Posts: 407	Re: Carb adj. You didn't mention if this was a typical truck engine or if you've cammed it up. By chance you've got a big cam and a fairly wild idle, it's possible that you'll have to revert to the old "drill a hole in the throttle plates" trick. This allows the engine to have enough air to idle correctly while not opening the throttle blades too much, which bypasses the idle circuit. If you've got a mild engine, just ignore everything I just said, er typed. __________________ 1972 C20, 402/700R4 - My first classic truck, bought in September 2005. 85% transformed from "Farm" to "Cool" status! 1970 Dodge Challenger 440, 4sp (my other toy) 12.67 @ 117 MPH, with a pathetic 2.022 60' 2007 Dodge Charger SRT-8 2008 Cadillac CTS All-American garage, baby!

01-19-2006, 02:15 AM	#1
53burb Senior Member Join Date: May 2004 Location: Queen Creek, AZ Posts: 1,005	Carb adj. I was messing with the A/F adjustment earlier. I have an 1806 Edelbrock (same as 1406 with Adjustable Valve Secondaries & 650CFM). If I turn the A/F screws in all the way, there is little or no change in idle at all. This is with both screws turned all the way in. I adjusted the floats, but no change. I yanked out the #1 cylinder spark plug a couple of weeks ago to set the engine at TDC to adjust the valves, and it wasn't fouled or looked like excessive fuel at all. I guess what I am asking is: Do I need a fuel regulator?? BTW it is a 350 with a recently replaced fuel pump... Last edited by 53burb; 01-20-2006 at 10:31 AM.

01-20-2006, 06:23 PM	#7
53burb Senior Member Join Date: May 2004 Location: Queen Creek, AZ Posts: 1,005	Re: Carb adj. The engine has a 268 Competition Cam in it. I don't know all the specs on it other than it has .454 lift on intake & exhaust on it, Edelbrock Performer 2101 manifold, HEI, & dual ramhorn exhaust with glasspacks. It idles fine, only the idle doesn't change when both screws are turned all the way in.



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