1968 Mustang Coupe, Stalling issue

NEGA0922

New Member
Mar 26, 2018
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I need some help!

I have a 68 Mustang Coupe with a 347 stoker that keeps stalling when i come to a stop. If i rev the engine right before i stop it sometimes doesn't shut off. I took it to a mechanic and he has checked the timing and the carb and says they are fine, he is currently still trying to figure it out and its been two week. Below is a list of what the car has please excuse the non technical spec list.

95 302 block 10:1 compression
MSD Ignition components
Holley QFT 750 SS carb
GT40 Heads
Lunati Custom Grind Cam 6:1
Hydraulic roller lifters
Mallory 140 Series fuel pump
Hooker headers
 
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WORTH

15 Year Member
Nov 18, 2002
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Cape Cod, Ma.
68.69.48.22
Is it auto or standard? at idle is it trying to pull the car, or will it sit still? Are you running a high stall converter and trying to idle too low??
 

tos

SN Certified Technician
Apr 27, 2001
880
66
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Cincinnati Ohio
Make sure you don't have any vacuum leaks. Can you tell if its flooding out or starving for fuel? Do you know what your fuel pressure is at the carb?
 

NEGA0922

New Member
Mar 26, 2018
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It has a manual T-5 transmission ,

It will sit still at an idle around 1000 rpm, does not try to pull forward, the only issue is sometimes if i hit the gas it wont rev up it will kinda bog down or hesitate, when i hit the gas right after it will rev up like its suppose to,

Stall converter I’ll have to look into it, not to sure

I am able to check the fuel pressure it reads 6 1/2 psi,

im not 100% sure if it have a vacuum leak but if im not mistaking i only have 3 lines on my car "Intake manifold to brake booster, distributor to the front port of the carb, and from the rear of the carb to valve cover,
 

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NEGA0922

New Member
Mar 26, 2018
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i dont think that it is starving for fuel only because when im cruising the cars response is good no issues
 

tos

SN Certified Technician
Apr 27, 2001
880
66
59
Cincinnati Ohio
Since you have a manual tranny then you wont have a stall converter. That's only for automatics.
You can have a vacuum leak at the base of your carburetor too, not just a line. Could be a leaking gasket or the base is not seated good or even a cracked carb base plate. Check for leaks around the carb base by squirting carb cleaner around it while its running. If it changes rpm while spraying then you are leaking/sucking air around the base. Check for cracks in your hoses if they aren't new.
Are you running a vacuum advanced distributor?
 

tos

SN Certified Technician
Apr 27, 2001
880
66
59
Cincinnati Ohio
Sorry just saw your picture so I see you are running vac advance dist.
Is that a rebuilt carb or new?
 

NEGA0922

New Member
Mar 26, 2018
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i just rebuilt the carb with new gaskets and components, I didn’t change any of the jets just cleaned them, I’ll definitely check around the carb for leaks and the hoses.
 

Neuron

Mustang Master
Nov 6, 2016
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Off idle bog sounds like accelerator pump problem. Stalling: I would check your float level.
 

tos

SN Certified Technician
Apr 27, 2001
880
66
59
Cincinnati Ohio
Sounds like maybe it's flooding out if not a vacuum leak. Check to see that your float is operating properly (not stuck open) and then check the float level.
 

NEGA0922

New Member
Mar 26, 2018
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Good morning, So a little update, I just got my car back from the mechanic yesterday, he told me that he check the timing, the carburetor and even hooked it up to a wide band o2 sensor and said that everything was reading fine. After three weeks at his shop i got a little frustrated so i picked it up. I again checked for vacuum leaks no issue there, i checked the float levels and they are both setting at mid range in the site glass. Yesterday i decided to give holley a call and ask a few questions and ended up purchasing a couple of items after explaining my issue to the techs, they recommended a new 8.5 power valve, 37 fuel nozzles, and a new pump cam orange in the #1 position. I plan on doing one at a time and see if either of them makes any difference. Other than that the car is coming together nicely. I installed new rear shocks, rear gt valance, trim around the grille, marker lights in the front, all in order to hopefully be able to enter the Spanish Trail Average joe car show in Crestview FL on the 21April18 as a work in progress car and win an award, we shall see. If you guys have any recommendations please let me know, thanks and have a good one.
 

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