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04-07-2012, 03:49 PM
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#1 |
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Registered User
Join Date: Jun 2009
Location: CENTRAL,NJ
Posts: 586
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Quick Stab???
After I replaced the intake manifold and carb on my 71 with a 307 smallblock, I can't get rid of stumble when you give it a quick stab of the throttle. If you accelerate at a steady pace it doesn't stumble and feels crisp, stab it and it wants to die! Any ideas? Thanks!
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04-07-2012, 03:52 PM
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#2 |
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Registered User
Join Date: Sep 2011
Location: United States
Posts: 163
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Re: Quick Stab???
When my truck did that it was the accelerator pump diaphragm
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04-07-2012, 04:21 PM
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#3 |
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Registered User
Join Date: Jun 2009
Location: CENTRAL,NJ
Posts: 586
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Re: Quick Stab???
Thanks I'll take a look at that? This is a Holley 600!
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04-07-2012, 04:35 PM
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#4 | |
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Registered User
Join Date: Sep 2011
Location: United States
Posts: 163
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Re: Quick Stab???
Quote:
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04-08-2012, 08:36 AM
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#5 |
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Registered User
Join Date: Jun 2009
Location: CENTRAL,NJ
Posts: 586
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Re: Quick Stab???
Is there a way to check to see if the accelerator pump is good?
Would a bad vacuum advance cause this problem? |
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04-08-2012, 10:26 AM
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#6 |
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Registered User
 
Join Date: Apr 2007
Location: Foster Rhode Island
Posts: 1,176
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Re: Quick Stab???
If you look down the throat of the carb,truck not running, and pull back on the throttle you should see it spray. and yes bad vacum advance could do that also.
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04-08-2012, 10:50 AM
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#7 |
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Registered User
Join Date: Jun 2009
Location: CENTRAL,NJ
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Re: Quick Stab???
Thank You!
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04-08-2012, 08:17 PM
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#8 |
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Registered User
Join Date: Apr 2007
Location: Foster Rhode Island
Posts: 1,176
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Re: Quick Stab???
Did you find the problem?
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04-09-2012, 03:14 PM
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#9 | |
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Registered User
Join Date: Jun 2009
Location: CENTRAL,NJ
Posts: 586
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Re: Quick Stab???
Quote:
Not yet, it is getting a shot of gas! ? |
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04-09-2012, 03:32 PM
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#10 |
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Registered User
 
Join Date: Jan 2011
Location: Chattanooga TN
Posts: 6,208
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Re: Quick Stab???
How many miles are on the engine? Could be a slack timing chain. (let's hope not)
__________________
Chad 1967 C10 SWB - Project Savannah - 6.0/4L80 *Currently underway* 1968 C10 SWB - TOTY 2018, 50th Anniversary Tribute Project * Sold * Pride and Joy 1986 Silverado Short Fleet - Scarlet *Sold* 1985 Silverado Short Fleet *Sold* 2022 Jeep Gladiator Mojave 2001 Jeep Cherokee XJ 4x4 - Lifted, Built 1992 Jeep Cherokee XJ 4x4 - Lifted 2013 Honda Accord EX-L v6 Coupe 6spd (wife's ride) |
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04-09-2012, 03:33 PM
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#11 | ||||
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"I ain't nobody, dork."
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,940
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Re: Quick Stab???
The holley 600cfm (1850) carbs have a dischrage nozzle (squirter) located inside the choke horn. It's held in by a big phillips head screw. You can remove it and put a largert squirter in there to give you more "pump shot". There will be a number stamped on the squirter. You will have to remove it to see the number. Whatever the number is... always go up or down a minimum of 3 numbers to get any effect from the change.
Larger number... more pump shot. Lower number... less pump shot. If it has the original discharge nozzle (squirter)... it should be a #31. Try a #34 and see what that gets ya. Also... what vacuum does the engine pull at idle. If it's an automatic... take the vac reading with the engine in gear with the brake on. That way we can determine what power valve you will need as well. Gary
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'cuz chicks dig scars... My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread. The Rebuild of Creeping Death after the wreck Quote:
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04-10-2012, 06:36 PM
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#12 |
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Registered User
Join Date: Jun 2009
Location: CENTRAL,NJ
Posts: 586
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Re: Quick Stab???
When I got home from work, I took a flashlight and looked closely, it seems that no fuel is coming from that nozzle. In fact, the arm to the accelerator pump barely moves no matter how I adjust it, and I can't really move it manually. Should I replace the diaphragm? Thanks... it's been decades since I worked on carbs!
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04-10-2012, 09:07 PM
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#13 | ||||
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"I ain't nobody, dork."
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,940
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Re: Quick Stab???
__________________
'cuz chicks dig scars... My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread. The Rebuild of Creeping Death after the wreck Quote:
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04-14-2012, 05:16 PM
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#14 |
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Registered User
Join Date: Jun 2009
Location: CENTRAL,NJ
Posts: 586
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Re: Quick Stab???
Well...I guess it's time for a new carb! I was going to order the parts for the accelerator pump, but before I took the carb off, I turned the idle mixture screws all the way in, the truck kept running, so I guess the power valve is shot! That's what you get when you buy a used carb. Instead of messing around and taking the carb on/off, I guess I should just buy a new one! Any suggestions on which one? Thanks for all the help!
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04-14-2012, 09:26 PM
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#15 | ||||
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"I ain't nobody, dork."
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,940
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Re: Quick Stab???
You only need a new power valve. Or you have a wicked vacuum leak from somewhere else. Unless you are looking for a reason to buy a new carb... but a new power valve can be changed in half an hour.
What manifold do you have it mounted on? Gary
__________________
'cuz chicks dig scars... My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread. The Rebuild of Creeping Death after the wreck Quote:
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04-15-2012, 08:45 AM
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#16 |
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Registered User
Join Date: Jun 2009
Location: CENTRAL,NJ
Posts: 586
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Re: Quick Stab???
The reason I thought about getting a new carb was because, it looks like in "addition too" the accelerator pump, the power valve is also bad! The carb 80457s looked brand new when I bought it, but every adjustment was way off!
Do you think I should just rebuild it? The intake manifold is an Edlebrock Performer. Thanks! |
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04-15-2012, 09:52 AM
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#17 |
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Registered User
Join Date: Apr 2012
Location: houston mo
Posts: 1
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Re: Quick Stab???
cant say i have messed with 600's much but do the have an adjustable cam that can be turned to trigger pump faster when throttle is pushed ? mite even make sure vac advance is hooked to ported vac and not manifold .
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04-15-2012, 02:09 PM
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#18 |
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Registered User
Join Date: Jun 2009
Location: CENTRAL,NJ
Posts: 586
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Re: Quick Stab???
THANKS EVERYONE! I replaced the power valve and accelerator pump diaphragm and now it runs like a big block! LOL. It only took a half hour and sure beats buying a new carb, again thanks for everyone's help!
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04-15-2012, 03:18 PM
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#19 |
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Sheetmetal Psycho
Join Date: May 2005
Location: athens PA
Posts: 515
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Re: Quick Stab???
That video was very informative. Thanks!
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I didn't say you were stupid, but I was thinking it... I need a check up from the neck up! Project "Rigginstine's Monster" 1971 C-10 longbed 355/4spd Future mods: 67 front clip Webby's Rigginations - where everything has potential! |
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04-15-2012, 04:00 PM
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#20 | ||||
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"I ain't nobody, dork."
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,940
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Re: Quick Stab???
Way cool dude! Glad you got it sorted out. Got your PM as well!
Good job! Gary
__________________
'cuz chicks dig scars... My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread. The Rebuild of Creeping Death after the wreck Quote:
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