Carb (?) Problems Back Took the car to its first show on Saturday and wondered if I'd make it home. It was missing REALLY bad except under heavy throttle. Took the plugs out today and all 8 were uniformly VERY clean. Too clean, I think. Indicates lean mixture, right? Did a compression check and all were 140-155 except one at 137. Not perfect but not that bad and not my current problem. Checked the mechanical fuel pump pressure and got 7.5# on the starter. Unless someone sees another problem, I'm gonna bite the bullet and buy a new carb. Comments, advice?
You keep saying that it is "missing" and also said it was missing really bad except under hard throttle. I know different people use different terms but if it is truely "missing" why aren't you looking at the ignition side of things? Check you coil and if you are running electronic ignition check that too. If you are still on the path that you think it is a fuel issue please, make sure you check your fuel lines and more important check the fuel filter(s). I have had a stopped up Fuel Filter make the car run horrible and drove me crazy trying to figure it out. Didn't happen to me personally but i have also seen a weak fuel line that would collapse under acceleration and made the car run so lean that it ran really crappy and it took the guy forever to figure that out also.
It was definitely mis-firing Saturday nite at idle and under light throttle. It'll smoke the tires (well, TIRE) with WOT. That plus the super-clean plugs make me think its lean on idle and light throttle. Car has new gas tank, new fuel filter, and new rubber fuel lines. When the power valve opens, its great so don't think its a fuel supply problem. Anyway, thanks for replying. I ordered a Summit carb. Decided I've messed with that old carb enough. Made it from three used (junk?) Holleys and a rebuild kit. Nice try but I'm giving up on it. A backup ignition is in the works too. I want one for trips. Have a Duraspark distributor on the way and, if it has a steel gear, will set it up with the GM HEI module as my backup ignition. A test of the backup ignition will tell me if its really an ignition problem, which I doubt. If I'm wrong I'll have a backup carb too.
I had moved up three sizes on the jets and it was running pretty good. Smooth idle and much less hesitation. Then Saturday night it got progressively worse on the way home. Got so bad I wasn't sure I'd make it home. I think there must be old gasket material or something stuck in there somewhere. I soaked that carb for a couple of days in carb cleaner and blew out all the passages with aerosol carb cleaner. Do I sound a little frustrated???
I think ur doing the right thing. If that don't work u'll have a pretty gud reason to look for something else.
Earl and I took a road trip to Barnett Performance today and replaced the Holley 650 Double Pumper on the 73 with a Holley 600. Engine sounds and runs great with it.
Ben awhile since you started this thread, but what are you running for igneition ? That could well be the problem, then again piecing three carbs together could also be a huge part of it too. I never had luck with old Holleys either. I now buy new, or those that look failrly new. And I don't have any problems from any like this.
Have an HEI distributor. Long story. Just don't see how it could be so strong and smooth under WOT with a bad ignition. Will soon know for sure.
If the ignition is acting erratic, it will do strange things. And many times seem to be a carb problem.
Summit carb is on and it seems really good. I was surprised at how close the adjustments were right out of the box. Strarted right up, ran on fast idle for a bit then settled right down. Floats were a little high but having the sight glass is a really nice feature. Took it for a short drive and NO stumble now.
