: Choke question and bad gas mileage on a 500cid.

06-13-09, 07:50 PM
Hey folks, haven't been around for a while but I still hang around.

So anyways, I have a concern about the 500. A couple months ago (January) I put the car in the garage. I pulled it out at the end of may to start enjoying her. But I noticed she had trouble starting.

Sometimes I have to really pump and hold the pedal to get her to start. And when she does start, she dies immediately unless I give her the gas.

Also when I'm on the highway, I get about 6mpg and top out at 50mph. This is weird, because when I drove her before, I would get about 20mph and top out at 100mph+.

The transmission is fine and shifts smoothly, but I have difficulty getting the speed necessary to shift, and I go quite slow. The car doesn't over heat, but the strain on the engine does make her run hot, sometimes too hot.

I think it's something somewhere on the carb. But I don't know why this would have suddenly happened. I had run the car a few times to roll her out of the garage for this and that, and she did fine. It was only when I just recently pulled her out that this problem came up. Any thoughts?


06-13-09, 08:03 PM
maybe a restricted exhaust, like a rodent nest

06-13-09, 08:14 PM
Take off the air cleaner after the car is completely warmed up. Look straight down the carb. Choke should be wide open like this (sorry pic so big):


Angry Matt
06-13-09, 10:18 PM
Sounds like it would be a carb issue, but I had similar symptoms when my points and condenser were shot.

06-22-09, 10:51 PM
I've had the exact problem with several rochester quadra's. check the needle valve and float. if they are sticking they will dump so much fuel that the car is drowning. likely just driving the dog out of it with lots of accelerator action will correct it. HAVE FUN!

06-23-09, 12:23 AM
If you got vacuum gages (they're not hard to come by if you don't) you can test for a restricted exhaust by connecting the gauge to manifold vacuum then increase the engine RPMs slightly. If the exhaust is restricted, the needle will drop to zero. Vacuum gauges can also be used to test for faulty ignition or valve timing. If the timing is off, the gauge will read steady at 10-14hg.

And to test the operation of the choke, without burning a tank of gas in the process, you can use a hair dryer or heat gun. The choke should slowly open as the temperature rises.

06-24-09, 12:09 AM
Thanks for the help, folks. I haven't had time to try these tricks yet, but I will soon. :)

06-24-09, 01:36 AM
I suspect varnish has built up in the carb, unless you added fuel stablizer before storing the car. If you clean out the carb really well, then fill her up with premium and go for a good long drive, everything should correct itself.

06-24-09, 04:09 PM
Could it just be a simple fuel blockage? It can happen if the car has long periods of inactivity and/or it often has the fuel tank run right down near empty.

06-25-09, 04:02 AM
Coule be anything from stuck choke to needles sticking in the seats on the carb.I would try a few suggestions on here,and when done run a bottle of Sea Foam through the gas and oil and vacuum lines.

08-19-09, 06:30 PM
Good news!

Today I fired her up, after spraying some barryman's in various parts of the carb. Then I dumped about a 1/4 cup of gas in too. She was tough to start as always and ran real rough. But after about 90 seconds, she started to rev high and smooth. She's back! Plenty of power, no smoke, so smell of gas! I'm so glad she'd back! Maybe the 100-degree weather helped, too.

It's a good thing she did, because I drove her to the paint shop. I know a good place that's doing all the body work and a first class repaint for $900. Yay! Can't wait 'til Monday! :D


08-20-09, 12:25 AM
Very good news indeed! Be sure to post plenty of pics when she's done.

08-20-09, 01:54 AM
I wouldn't mind finding a first class paint shop that will do body work and repaint for $900. I have some small flaws in my paint. Scratches, blemishes, chip marks...no rust.