Erratic Idle Speed

Hi Guys,

I had the 440 in my '71 Charger rebuilt last year. I didn't drive it a whole lot, but it ran fine.

I started it this spring and I am getting an erratic idle.

It's set at about 900 rpm, but it dips and revs between about 750 and 1,000 rpm as it sits there idling, and sounds terrible when it starts to idle down.

If I put the idle speed up to 1,100-1,200 rpm, it seems to mostly smooth it out, it might fluctuate 100 rpm, but not 250-300 rpm like it does at idle.

The car sat all winter without being started. I am wondering if this might be a vacuum leak, or what other possibilities might be.

Thanks for the help.

Greg

Could be about a dozen things, but if it were mine I would start on the fuel side, based on the fact that it has been sitting.

How long has the gas been sitting? Put some fresh gas in it.
Carb could be crudded up. Especially check the idle adjustment screws.

I would pull the idle mixture screws & shoot a 2 second blast of brake kleen or starting fluid into each hole with the thin red straw then replace the screws. If at first you count the # of turns down to lightly seated you can easily/quickly return them to their original position.

Thank you, I wasn't really thinking of the gas, but I guess it's getting to be 9 months or more old. I'll work on it being a carb/fuel problem first.

My first three guesses....
1. Vacuum leak, like a cracked hose or one that popped off
2. Bad gas....siphon out the tank completely...burn it off in your lawn mower or use 3 gal. at a time in your daily driver...and fill the tank with premium
3. A spark plug wire fell off (or one plug fouled)

If it runs normal while partially taking air away from the top of the carb it is getting air from somewhere else.