what causes this?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**hilljob26** · 01-19-2006, 10:12 PM

well,my dad put a new holley on his truck,he messed with it alittle bit,seems to run great,but now when he shuts it off,it deisels a little,how can he fix that,any ideas,its a new holley 600 that does not have adjustable floats,its called a next generation needle/seat,just doesn't look right without that nut and screw on the top,but seems to work okay,just this little problem.....mike

northcountry67 · 01-19-2006, 10:53 PM

It sounds to me like your timing is too advanced. It could be a combination of a number of things like the timing along with the idle too high. Check your timing with a light.

*Billla* · 01-19-2006, 11:09 PM

Quote:

Originally Posted by northcountry67

It sounds to me like your timing is too advanced. It could be a combination of a number of things like the timing along with the idle too high. Check your timing with a light.

Novaguy73 · 01-19-2006, 11:12 PM

Ill third that...

crazy longhorn · 01-19-2006, 11:25 PM

Call me #4 on that! Try setting the idle speed down, & see if that helps(assuming the timing was not changed, & there was no prob before)

L

Longhorn Man · 01-20-2006, 12:06 AM

third choice, it may be a little lean.
If timing is good, and idle speed is good, fatten up the mixture a bit.

rkarr · 02-10-2006, 11:16 PM

Quote:

Originally Posted by Longhorn Man

third choice, it may be a little lean.
If timing is good, and idle speed is good, fatten up the mixture a bit.

I agree.
if she's lean, she'll do that...

cduster · 01-20-2006, 01:37 AM

I'm going with mixture also.

Dan

cypress TX 72 · 01-20-2006, 01:43 AM

Timing !! (I'm with the other guys -I guess #5)
Try retarding it a little

krue · 01-20-2006, 02:00 AM

Check idle first.

mike nutt · 01-20-2006, 06:43 AM

good call everyone!

**hilljob26** · 01-20-2006, 07:42 AM

right on,thats what i needed to know,we never touched the timing,but will look into it.......mike

Longhorn Man · 01-20-2006, 11:16 AM

If the timing was never touched... then it should be fine... or good enough anyways.
Idle speed... it would be noticeable IMO... 850 RPM isn't going to do it, we're talking like 1000 RPM.
So that leaves mixture.

68/72parts · 02-10-2006, 03:58 PM

Check your idle speed first and set it to spec. And see what happens. Then check your timing just like the last few replies. Generally it will run on if your idle is to high, when its set at a higher than norm idle the throttle doesnt close enough to stop the air and fuel flow and the truck will continue to run. Make sure that your throttle linkage is set properly as well especially if you changed from a different style carb!! Just my 2bits..

boundstaffpress · 02-10-2006, 04:12 PM

If you just replaced the carb. It is very likely a linkage problem. I went two barrel to quadrajet. The linkage hung up and kept the throttle from closing. It took 6 months of messing with throttle and timing adjustment before I solved it by adjusting my thottle linkage bracket.

Sweet72 · 02-10-2006, 09:33 PM

Stock carb more than likely had a idle stop solenoid to close the throttle plate completely with the key off. If your holley throttle isn't closing as somebody already mentioned it will deisel with the key off.

01-19-2006, 10:12 PM	#1
hilljob26 Registered User Join Date: Dec 2004 Location: Gypsum Kansas 67448 Posts: 1,681	what causes this?? well,my dad put a new holley on his truck,he messed with it alittle bit,seems to run great,but now when he shuts it off,it deisels a little,how can he fix that,any ideas,its a new holley 600 that does not have adjustable floats,its called a next generation needle/seat,just doesn't look right without that nut and screw on the top,but seems to work okay,just this little problem.....mike __________________ 21 2500hd duramax 58 apache HILLJOB GRAPHIX--for all your graphic needs My build thread http://67-72chevytrucks.com/vboard/s...d.php?t=542497 LS ENGINE SWAP INFORMATION THREAD http://67-72chevytrucks.com/vboard/s...d.php?t=377348 4l60 to an NP205 http://67-72chevytrucks.com/vboard/s...43#post3697343

01-19-2006, 10:53 PM	#2
northcountry67 Registered User Join Date: Dec 2005 Location: Lengby, Minnesota Posts: 225	Re: what causes this?? It sounds to me like your timing is too advanced. It could be a combination of a number of things like the timing along with the idle too high. Check your timing with a light.

01-20-2006, 12:06 AM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: what causes this?? third choice, it may be a little lean. If timing is good, and idle speed is good, fatten up the mixture a bit.

01-20-2006, 01:37 AM	#8
cduster Registered User Join Date: Oct 2002 Location: S.W. Michigan Posts: 403	Re: what causes this?? I'm going with mixture also. Dan __________________ Good Judgment comes from experience. Most experience comes from bad judgment.

01-20-2006, 01:43 AM	#9
cypress TX 72 Saving one 72 at a time!! Join Date: Sep 2005 Location: Cypress, TX Posts: 261	Re: what causes this?? Timing !! (I'm with the other guys -I guess #5) Try retarding it a little

01-19-2006, 11:12 PM	#4
Novaguy73 Registered User Join Date: Oct 2005 Location: Waterloo, Ia Posts: 73	Re: what causes this?? Ill third that... __________________ -73' Nova 350 5-speed 9"rear, Runs 11's drives anywhere... -72' C10 350 Auto 12 bolt, runs 19's?? drives to work!

01-19-2006, 11:25 PM	#5
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,403	Re: what causes this?? Call me #4 on that! Try setting the idle speed down, & see if that helps(assuming the timing was not changed, & there was no prob before) L __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

01-20-2006, 02:00 AM	#10
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Re: what causes this?? Check idle first. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

01-20-2006, 06:43 AM	#11
mike nutt 69fatmotor Join Date: Oct 2005 Location: bama Posts: 660	Re: what causes this?? good call everyone!

01-20-2006, 07:42 AM	#12
hilljob26 Registered User Join Date: Dec 2004 Location: Gypsum Kansas 67448 Posts: 1,681	Re: what causes this?? right on,thats what i needed to know,we never touched the timing,but will look into it.......mike __________________ 21 2500hd duramax 58 apache HILLJOB GRAPHIX--for all your graphic needs My build thread http://67-72chevytrucks.com/vboard/s...d.php?t=542497 LS ENGINE SWAP INFORMATION THREAD http://67-72chevytrucks.com/vboard/s...d.php?t=377348 4l60 to an NP205 http://67-72chevytrucks.com/vboard/s...43#post3697343

01-20-2006, 11:16 AM	#13
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: what causes this?? If the timing was never touched... then it should be fine... or good enough anyways. Idle speed... it would be noticeable IMO... 850 RPM isn't going to do it, we're talking like 1000 RPM. So that leaves mixture.

02-10-2006, 03:58 PM	#14
68/72parts Registered User Join Date: Jan 2006 Location: Chilliwack B.C Posts: 59	Re: what causes this?? Check your idle speed first and set it to spec. And see what happens. Then check your timing just like the last few replies. Generally it will run on if your idle is to high, when its set at a higher than norm idle the throttle doesnt close enough to stop the air and fuel flow and the truck will continue to run. Make sure that your throttle linkage is set properly as well especially if you changed from a different style carb!! Just my 2bits..

02-10-2006, 04:12 PM	#15
boundstaffpress Jamie Hyneman is my twin Join Date: Nov 2005 Location: La Junta, Colorado Posts: 705	Re: what causes this?? If you just replaced the carb. It is very likely a linkage problem. I went two barrel to quadrajet. The linkage hung up and kept the throttle from closing. It took 6 months of messing with throttle and timing adjustment before I solved it by adjusting my thottle linkage bracket. __________________ Justin SOLD 1967 K10 Fleetside, 283, Front and Rear Posi SOLD Color Wiring Diagrams Now in High Resolution V8 and Cab and Cab and Chassis

02-10-2006, 09:33 PM	#16
Sweet72 Registered User Join Date: Nov 2003 Location: Alexandria, VA Posts: 1,534	Re: what causes this?? Stock carb more than likely had a idle stop solenoid to close the throttle plate completely with the key off. If your holley throttle isn't closing as somebody already mentioned it will deisel with the key off. __________________ '72 GMC SWB C1500 Custom, frame-off in progress. 383 SBC, 9:1CR, Comp Cams XE262H, Scat internal balanced crank, Eagle SIR 6" rods, Keith Black dish pistons, Dart Iron Eagle 72/180 heads, Weiand Stealth intake, Stewart stage I water pump, Holley 4bbl vac sec, TH350 with B&M Shift Improver Kit. 12 bolt positraction.



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