My car feels like it has a 2 barrell smoetimes. When I floor it, it stumbles for 1/2 a second then starts to go. Does this sound like a fuel pressure porblem? Thanx.
First of all, what kind of carb? Sounds to me like a lean condition caused by huge hole in the fuel curve. check accel. pump(s), power valve. These are two circuits that provide "extra" fuel to fill that huge hole that happens when you snap the throttle open. So no, I don't think initial bog has anything to do with fuel pressure. There is more than enough fuel in the bowl(s) for initial launch. If you answer the first question, I'll try to help if I cano No: HTH Jeff
hello Actually, when I floor it off the line it does not do it, it is when I am cruising along and floor it. It kind of falls on it's face for 1/2 a second, like it is thinking of stalling. The carb is a 800 q-jet that I rebuilt a couple months ago. How do you you adjust the valve and pumps? Do I only need to take off the top of the carb? Thanx so much for your help.
Hi, You should put a first name in your sign. block.. Not a Q-Jet guru by any means, but I'll try. Have you checked the float level? Jeff
Hi John, nice to meet you! There are different float measurement settings depending on your model and year. Did you set yours accordingly? It kinda sounds like your secondary air valve is opening to fast. Did you know there is an adjustment screw up under the pass. side? You have to have a SHORT screwdriver to get to it, or take the carb off and turn upsidedown to get to it. Very sensitive to adjustments. MTH Jeff
John, Two things to check on a Q-jet. First is the air valve spring adjustment. The air valves are on top at the rear. With the motor off, tip them in with your finger, then let go, and they should immediately close. As long as they snap back the adjustment may be OK. Second thing is the choke vacuum break on the passenger side front of the carb. It is designed to slow the opening rate of the air valves. Start the car, and let it idle. Try to tip in the air valves. You should not be able to. The choke vacuum break should hold them solidly closed. If you can tip them in, the vacuum break is leaking and is allowing the air valves to flop in when you nail it, giving you the dreaded bogggggg.
hello The choke hardware is all gone. I think the adjustment for the upper 2 flaps is correct. I have played with them before. I will check again. I don't know anything about float adjustments. How should I check float level? Thanx for the help guys?
If the choke vacuum break is gone, you will have a giant bog. The airvalves need to tip in not flop in. The vacuum break slows the airvalve action down. Do you know what I'm referring to as the vacuum break??
hello No, I don't know what the vacuum break is. Are you saying that with out the top flap (are the upper flaps called valves?) over the primaries I will have a bog? Thanks so much for your help.
John, Here is a picture of a quadrajet carb. On the passenger side of the carb is a white diaphram that is hooked to the carb with a piece of vacuum tubing. It serves two purposes. One, it opens the choke a set amount after starting a cold engine, and two(more importantly) it has a metal link to the airvalves at the rear of the carb. The airvalves are the two plates on top at the secondary section of the carb. With the engine off, you should be able to push them in with your finger, and they should return to the closed position when you remove pressure on them. With the engine running, vacuum should pull the diaphram link in, and hold the airvalves closed. You should not be able to push the air valves in when the engine is running. If you can, then look at the vacuum break, and see if it is pulling its link in. If it is missing or defective, your secondarys will not come on smoothly and the engine will bog. Hope that explains it.
