Q: I have a couple of problems I hope you can help me solve. I have a 440 Mopar in my Charger that shakes right after the first cold startup, but only if it’s been longer than 24 hours since the engine was last running. I was told this might be because the electric choke on my Edelbrock carburetor might be set “too aggressively.” Does that make any sense?
When I’m driving the car every day, it will start cold with one pump or no pump of the gas pedal. But if it sits longer than a day, I can pump the pedal three times and turn the ignition key, but it won’t start until I press the gas one more time. Does the diaphragm in the carb’s accelerator pump have anything to do with this?
A: The shake on the cold startup is because the engine has been flooded. You might try leaning the choke out one notch and set the fast idle to 1,600 rpm. The Edelbrock/AFB-style carburetors have been known to have a fuel drainback problem when used on big block Chryslers. You might want to install a small electric fuel pump along with the mechanical pump to help reprime the carburetor on cold startup.
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Similar problem with my Chev 454 with 750 Edelbrock carb. Should I install a inline electric pump and should it go before or after that mechanical pump.
A one way valve in the fuel carburator feed line is the best to prevent drain back.
Sure. But this is a problem with internal leaking. The carb drains into the engine, diluting your oil and emptying your float bowl.
Only on Mopars? I believe the AFB/Edelbrock carb reliably leaks down no matter what engine you install them on. I’d say “worst 4-barrel ever”, but there was the old Rochester carbs, so…
I had an edelbrock on a 350 that drained dry after sitting a week/month. Gave up and swapped to a holly.
Had an Edelbrock 650 on a 67 Camro 350. Didn’t drive the car very often and the carb was almost always dry when I tried to start it. Switched to a holly and never had another problem. It was the drain down issue.
The shaking may not be a fuel issue, typically they are not that rough, or shaky. However, a miss firing cylinder is also possible. When an engine is shut down, a cam lobe can come to rest on a lifter, if it is weak it will leak down and take a bit to pump back up.