57 T bird Holley 1273-2S idle problems

[32Fiver]

We have in the shop a 57 T bird 312 with Holley 1273-2S 554 that sat on the car not run for 35+years, since it sat so long not running we replaced the tank, flushed the lines, installed new fuel pump and rebuilt the carb. The carb was cleaned in my ultrasonic cleaner using cleaning solution made for carburetors, rinsed it, used carb cleaner on all the ports and holes then blew them out with compressed air.

Installed the carb and started right up running on fast idle then when the engine warms up and the choke opens the engine dies. When closing the choke to run rich it will idle down until it starts to load up. But when the choke plate is open it dies. When hitting the accelerator it is responsive and runs great just will not idle down below 2000rpm. We checked for vacuum leaks and even changed the intake manifold gasket. Seems there maybe something wrong with the idle circuit. Any ideas and help would be appreciated, Thanks

Mike Mondrella
Mondrella’s Hot Rod Shop

[scicala]

I've been doing all USA carbs since '67, and mainly 50's Ford products. I know you have checked for a vacuum leak, but it does sound like it may be that. Also posable there is something wrong in the idle circuit.
I assume you have tried to adjust the idle mixture screws on the front metering body to make a richer idle.
Have you disconnected all vacuum lines from the engine and plugged them ? Like to the power brakes or vacuum assist wipers to help eliminate a vacuum leak as a possibility.
Other than that, all I can suggest is to take the carb apart again , and recheck everything in the idle circuit.
If you think it's for sure a carb issue and you can't figure it out, I would be glad to look at the carb for just the shipping cost back and forth. I live north of Detroit in Shelby Township. I see you're in Grand Rapids.

Sal (586) 612-1650 [email protected]

[32Fiver]

Sal,
Since we have check all circuits for vacuum leaks I’m pretty sure now the idle circuit in the body or possibly the metering block may be plugged even though they looked to be cleanwith spraying carbs cleaner and blowing compressed air through every hole.

Didn’t mention previously we had 1450 single feed Holley on the self we put on and ran great and idled down perfect. Then not sure if he had any of the vacuum line hooked up to this carb so before tearing into it and rechecking it will have the vacuum lines rechecked and one I don’t know checked was the dizzy vacuum advance so will have him check it too.
Thanks for your comments and input and will let you know if we get it figured our.
Mike

[scicala]

Sounds good Mike. Good luck, and keep everyone posted when you find something.

Sal

[32Fiver]

We found the problem and now solved. After checking and trying about everything imaginable, we found the primary metering block was the problem and had never seen a metering block be the fault in all the hundreds of Holley’s I have worked on. In finding the problem we replaced the meter block with one off another spare 4150 carb to try and immediately it ran and idled down perfectly.

[scicala]

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Thanks for posting the fix. I also ran into the same issue only one time in my life, and I've done hundreds of Holley 4 and 2 barrel carbs.

Sal