engine ideling way to fast - The 1947 - Present Chevrolet & GMC Truck Message Board Network

wibilly · 09-09-2007, 02:34 AM

my truck wont idel down both primarys and secondarys are closing all the way idle screw is backed all the way out to where it does not touch the throtel at all. it seem to run smother with idel mixture screws backed out excessivly this also gives me the highest vacume reading when tuned to run the best it idels at about 1500 rpms to get it to idel down i have to make it run ruff by retarding the timing and leaning the idel mixture both causing a drop in manifold vacume the carb worked perfect on the 350 i removed it from it is on a 305 now with a newer styel intake with the newer base gasket does this sound like a base gasket problem to you guys, it dosen't seem to gain any r's when i spray around it with carb spray

'68 longbed · 09-09-2007, 02:53 AM

sounds like timing is 180 degrees out to me

bad6772 · 09-09-2007, 03:20 AM

i agree

68gmsee · 09-09-2007, 10:04 AM

What carb is it?

If everything else looks normal-timing, no vacuum leaks, choke adjustments, etc., then I'd remove the carb and take a good look at the throttle plate, choke links, etc. to make sure they're closing properly and not staying at partial throttle.

wibilly · 09-09-2007, 12:14 PM

it's a remanufactured q jet off a 69 350 it is on a 80 or newer 305. base gaskets were totaly diffferent 305 was thick and 350 was two gaskets and a stainles plate i used the one from the 305 because the 350 one hung over the manifold in the front where the long slot was i belive for exuast heat for the choke

**WorkinLonghorn** · 09-09-2007, 12:37 PM

Stuck "fast idle cam" ? It's supposed to idle at 1500 during warm-up and there is a little "cam" that keeps the idle up until about 1/2 way warm.Check that the mechanism that kicks this cam is functioning.

Longhorn Man · 09-09-2007, 01:25 PM

I think you have a massive vacume leak. The mis match basees... I've seen this, and decided not to run said carb becouse I suspected there would be a huge vac leak.

09-09-2007, 02:34 AM	#1
wibilly Senior Member Join Date: Nov 2005 Location: northwestern wi Posts: 2,111	engine ideling way to fast my truck wont idel down both primarys and secondarys are closing all the way idle screw is backed all the way out to where it does not touch the throtel at all. it seem to run smother with idel mixture screws backed out excessivly this also gives me the highest vacume reading when tuned to run the best it idels at about 1500 rpms to get it to idel down i have to make it run ruff by retarding the timing and leaning the idel mixture both causing a drop in manifold vacume the carb worked perfect on the 350 i removed it from it is on a 305 now with a newer styel intake with the newer base gasket does this sound like a base gasket problem to you guys, it dosen't seem to gain any r's when i spray around it with carb spray __________________ common sense isn't so common anymore

09-09-2007, 02:53 AM	#2
'68 longbed Registered User Join Date: Jun 2007 Location: mississippi Posts: 181	Re: engine ideling way to fast sounds like timing is 180 degrees out to me __________________ "spiiiider pig, spiiiiider pig, does whatever spiiiider pig does. "

09-09-2007, 03:20 AM	#3
bad6772 Official Site Guitar Shredder Join Date: May 2006 Location: Oz Posts: 3,955	Re: engine ideling way to fast i agree

09-09-2007, 10:04 AM	#4
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: engine ideling way to fast What carb is it? If everything else looks normal-timing, no vacuum leaks, choke adjustments, etc., then I'd remove the carb and take a good look at the throttle plate, choke links, etc. to make sure they're closing properly and not staying at partial throttle.

09-09-2007, 12:14 PM	#5
wibilly Senior Member Join Date: Nov 2005 Location: northwestern wi Posts: 2,111	Re: engine ideling way to fast it's a remanufactured q jet off a 69 350 it is on a 80 or newer 305. base gaskets were totaly diffferent 305 was thick and 350 was two gaskets and a stainles plate i used the one from the 305 because the 350 one hung over the manifold in the front where the long slot was i belive for exuast heat for the choke __________________ common sense isn't so common anymore

09-09-2007, 12:37 PM	#6
WorkinLonghorn Senior Member Join Date: Dec 2006 Location: Studio City, Calif. Posts: 2,887	Re: engine ideling way to fast Stuck "fast idle cam" ? It's supposed to idle at 1500 during warm-up and there is a little "cam" that keeps the idle up until about 1/2 way warm.Check that the mechanism that kicks this cam is functioning. __________________ '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.

09-09-2007, 01:25 PM	#7
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: engine ideling way to fast I think you have a massive vacume leak. The mis match basees... I've seen this, and decided not to run said carb becouse I suspected there would be a huge vac leak.



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