I know many things can cause a car to idle poorly but I had a specific question while troubleshooting. My 1948 Cadillac flathead fired up and idled smoothly numerous times while I was getting other things in running order after sitting 1.5 years with the previous owner. He lost the air filter assembly so I don’t have it. The first time I took the car out it idled smoothly and ran well for the first 3 miles, then it seemed to starve for gas and would not idle well at all, but would run fairly well at higher RPMs. It stalled several times and was very difficult to start. Before I pull the carburetor apart I just wanted to know if running it without the air filter assembly might be the culprit. The carburetor is a Carter 595S. Any advice is greatly appreciated.
Sitting a year and a half, open intake. It's a crap shoot, one thing at a time. Need to look at it all
First, it's not...the "car" that's not idling, it's the engine ! Beside the comments above, remember, the air and fuel bleeds at the top of the carburetor are very small, and CAN...be plugged with junk / garbage very easily. Try a few squirts of Brakleen into those small holes with the "engine" running. Have someone keep the engine running when you do this. Don't just spray the stuff around the area. Use the plastic tip and aim the liquid directly into the bleed holes. May take a few shots. If that doesn't help, find a piece of wire small enough to stick into the holes to try to clean them. A single piece of stripped electrical wire might work. If THAT doesn't work...a full, normal carburetor rebuilding / cleaning is next in line. Mike
ff it was mine, I'd remove the 2 idle mixture screws. Give holes a few shots of carb cleaner. Maybe followed by a few shots of compressed air. Repeat a few times for good measure. Seat screws snug. Then back off one turn. Go from there.
> >would not idle well at all, but would run fairly well at higher RPMs. .> > >>Shit in a fuel filter would be my first guess>> If stock, prolly only a rock strainer in pump.
Been there before with an OT car. I rebuilt the carburetor twice, then said eff it, buy one. Same thing. Yep, insulation was getting sucked down , but mine idled fine, but crapped out with RPMs getting higher.
If you didn't flush out the tank I would suspect crud from the tank getting up to the circuits in the carb. A can 0f good carb cleaner is your friend here flushing the air bleeds on top out and then pulling the mixture screws and flushing out the idle circuits from that end and putting the screws back in. I'd suggest gently screwing them in while counting the turns so I could set them back the same when I put them back though as even if that isn't perfect it is an honest starting point . Even a cheezy little chrome air cleaner with a paper filter is a lot better than no filter and you need to get something on it before driving it. Personally I would put a metal inline Filter between the tank and the Fuel pump to catch as much crud coming out of the tank as I could. A non vented cap will usually let the engine run for bit and then starve it For Fuel (Lower case F is messed up) and cause the engine to die and not want to start until the vacuum in the tank isn't there and then it will start and run For about the same amount of time again. l
Have you changed the fuel filter , if not do that and cut your old filter apart to see what’s coming from your tank . Make sure the gas cap is vented . Try running ( idling) with the gas cap off or loose .
Like everyone is saying, you need to check to fuel system and what it is delivering. Gsoline, tank, lines, pump, filter, carb. Almost any properly sized air filter should not affect how the engine is running alone, except as noted (holding insulation out of the inlet).
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