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1972 Chevy Impala Stalls When Idle?

I’ve been trying to get her up and running for awhile now in order to sell her. I bought the car from a neighbor who never drove it (only 50k miles on it) and my dad had a great idea to get some new parts for it…I just wanted the car as it was… So we replaced the original carb for a newer carb and my father did all he wanted to do to it (I do know he took off the distributor, did some thing with the clutch, and replaced the fuel line to the distributor).

Well, when all was said and done (after a year and a half), the car is back up and running BUT when it sits idle it stalls. It will only stay running when you keep on the accelerator to rev the engine. As soon as you let up, the RPMs drop and she stalls. He’s not sure why it’s doing it, and I’m even less sure.

What are some reasons/causes/possible fixes for this?

If it sat for a year and a half without running the carb’s probably gunked up, maybe needing a rebuild to clean it out. It ran fine when you last dove it, I take it?

The problem might be with plugged idle jet circuits.

Locate the idle mixture screws on the front of the carburator. Turn the screws all the way in and then turn them back out 2-1/2 to 3 turns. See if it now idles. If not, then the carb has to be taken apart to determine why the idle circuit isn’t working.

Have you been using ethanol gas in the vehicle?


When I first got it, it ran just fine. But my dad is a self claimed “gear head” and loves to upgrade cars. I just got the new carb and put it on last month so it’s not gunked up (the original one was bad though, but it still ran).

We have good ole petroleum gas in her right now, no ethanol. I will try turning the idle screws tomorrow once it gets light out to see if that helps.

Did it ever run right with the new carb?

After doing testers advice, but I would start with 1.5 turns first, if it still doesn’t work, I would start looking for a vacuum leak.