Won.t idle

7173Mustangs.com

Help Support 7173Mustangs.com:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

alarmrick

Well-known member
Joined
Oct 17, 2011
Messages
134
Reaction score
2
Location
Brewster MA
My Car
1971 Mach 1
351C-4V
I have a 71 351 4V with a holley carb. The car has been running great for some time now. I went for a ride yesterday for about 1/2 hour. I stopped the car for about 5 minutes. The car was a little hard to start after the rest but would not idle. It kept stalling. I was able to make it home and put it away for the night. Now when I try and start it, it revs very high on cold idle and then stalls when the choke comes off. It runs ok at high revs but not as smooth as it was, Any suggestions on where to start?

Thanks,

Rick

 
I have a 71 351 4V with a holley carb. The car has been running great for some time now. I went for a ride yesterday for about 1/2 hour. I stopped the car for about 5 minutes. The car was a little hard to start after the rest but would not idle. It kept stalling. I was able to make it home and put it away for the night. Now when I try and start it, it revs very high on cold idle and then stalls when the choke comes off. It runs ok at high revs but not as smooth as it was, Any suggestions on where to start?

Thanks,

Rick
Check that choke is operating correctly.

Check for vacuum leaks.

 
Another possibility is that trash got caught in the idle circuitry, but it is easier to check for a vacuum leak first.

 
Agree on the vacuum leak. Classic symptoms. When it happened to me it turned out to be the intake manifold. Pulled it and replaced the gaskets to resolve the issue.

 
The choke is working fine. I checked the vacuum and it was over 15 at the carb and over 20 at the manifold. I checked all the lines and everything is holding the vacuum except the ram air which leaks a little. I bypassed it but it did not make a difference. Any other suggestions?

Thanks

 
A clogged idle circuit may be the problem, you could try removing the idle mixture screws (make sure to turn them all the way in first and count the turns they were set to) and blow in to the carb with compressed air and carb cleaner to clean the idle bleeds and passages.

 
Just because the engine is creating vacuum does not rule out leakage. Spray carb cleaner ( a little burst at a time) at the base of the carb, edges of the intake, etc.

 
You guys are the best. I found a broken vacuum cap at the back of the carb. The best way to do it was with the propane torch. The carb cleaner is ok but it will take the paint off the motor.

Thanks again

 
Back
Top