If the idle mixture screws have no effect, you are not on the idle system of the carburetor. The primary throttle blades are too far open. Turn the distributor and advance the timing and/or connect your vacuum advance to manifold vacuum. Back out the idle speed screw until the idle comes down as much as possible without stalling. Check the idle mixture screws then, they should be responsive.
OK I'll go try that. Took a quick video this morning http://www.youtube.com/watch?v=5hYeV_epgrw I also noticed that the primary throttle blades each have a small bypass hole drilled in them, could that be causing problems? The primary throttle blades look like they are pretty well closed
Someone else has modified your carburetor. Drilling holes in the throttle blades is the wrong way to do things. Who knows what else was done. If it were my carburetor, I bring it to someone who knows what they are doing, and have them look it over.
Hooked up manifold vacuum to the advance, backed the idle off to the point the screw is not touching the lever and turned the mixtures screws all the way in and nothing changed. When I cracked open the secondary air flaps a tiny bit, it died right away.
I have access to some extra qjet parts, I can put on some throttle blades without air bleeds at least.
Yes, I'd start there. People drill holes in the throttle blades to allow more air for the carburetor to idle with a big cam, but that is the wrong way to do things. Like I said, who knows what was done to this carburetor. I'd start with a good rebuild and while you are at it, see what the jetting is like. If the idle mixture needles have no effect, it isn't running on the idle system.
Have a look at this thread. Cliff Ruggles has some input here: http://www.v8buick.com/showthread.php?t=231423
I may have located the problem or part of it at least, seems as if one of the secondary or both of the throttle plates aren't 100% closed off, moved the linkage on the drivers side when it was idling and everything smoothed out. Looks like the shaft might be binding or a blade isn't 100% set. I'll report back
I would suggest going with a Buick 350 carb, the idle passages etc are different in the different carbs....
Got it straightened out, there was some binding in my base plate on the carb, not sure if it is the throttle blades or if it's the secondary shaft itself, but I swapped base plates with a different carb and it's 100% better. I do have a stumble when I get on the throttle fast, nothing major but it's time for some tweaking. Thanks to everyone for their help!
Happy to hear you fixed it but-- I thought opening the secondaries helped, now you think the problem is that they aren't closing. I have similar issues (but Holley) , trying to learn, not trying to be a pita. Thanks
Well opening the secondary air flaps (the top flaps on the carb) helped by allowing some air in, the lower flaps (throttle blades) weren't closing up for some reason and allowing fuel to get into the intake. A different base plate on the carb solved the problem... the only thing I'm unsure of is why it was letting fuel by. I'm by no means any sort of expert on this stuff And this morning I went to start the car to go for a drive and the fuel pump had fuel literally running out of it, not leaking from either the inlet or the outlet - but it's leaking from the body of the fuel pump. Thankfully I have a new one in the garage for just this type of situation
