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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: kmcbride74 on June 29, 2011, 08:56:53 pm

Title: Hesitation at low rpms...
Post by: kmcbride74 on June 29, 2011, 08:56:53 pm: All,

BACKGROUND: Wrapping up my 305->350 swap, in fine tuning mode. Truck runs well for the most part, idles well, nice power from about 1/4 throttle all the way to the floor, have timing set per cam spec., 12 degress btdc, valves adjusted.

SYMPTOM: When taking off from a stop, when I first press the gas, it hesitates for 1-2 seconds. Immediately after that point it runs strong, no missing, no hesitation.

Would this indicate that I need to retard the timing a hair or advance it?

Or, do you have suspicions of anything else that might be the culprit?

Thanks in advance!
Title: Re: Hesitation at low rpms...
Post by: topp on June 29, 2011, 09:43:07 pm: 305 or 350 (no need to mention what it was)?
tbi or carb?

Hesitation off idle is usually fuel/air related...
Title: Re: Hesitation at low rpms...
Post by: kmcbride74 on June 30, 2011, 08:53:29 am: Its a 350 with carb, Edelbrock 1406, brand new, supposedly not needing any adjustment...
Title: Re: Hesitation at low rpms...
Post by: Captkaos on June 30, 2011, 09:37:47 am: Don't assume that it is setup perfect right out of the box. You will need to preform some kind of adjustment.
Title: Re: Hesitation at low rpms...
Post by: jaredts on June 30, 2011, 12:58:47 pm: What's your idle speed? You could experiment with the different holes on the accellerator pump to see if that helps.
Title: Re: Hesitation at low rpms...
Post by: kmcbride74 on June 30, 2011, 05:04:41 pm: at operating temp right at about 700 rpm...I dont think it's an idle adjustment issue.
Title: Re: Hesitation at low rpms...
Post by: topp on July 01, 2011, 11:23:07 am: Quote from: kmcbride74 on June 30, 2011, 05:04:41 pm
at operating temp right at about 700 rpm...I dont think it's an idle adjustment issue.

Auto or stick?
Auto should be 700-750 in drive, stick about 550-600...

It sounds more like a jet issue....
Title: Re: Hesitation at low rpms...
Post by: ohio hab on July 02, 2011, 06:34:45 am: Need to advance the timing , 2 degrees is a good starting point, or needs the accelerator pump adjusted , or bigger squirter. Also carb could be lean. Iam not familar with Edelbrock carb's, I alway's run Holley's, but your symptom's, apply to any carb.