I've been having an ongoing vacuum issue on my car, you can see what I've been doing here: http://www.v8buick.com/showthread.php?s=&threadid=52496 It seems like it might get looked at a little more here. p My main question for now is, I have all of the port blocked off, except for the one on the passengers side, which is running directly to the vacuum advance on the distributor. When I put my thumb over the vacuum line, it pulses, instead of being a steady vacuum. Should this be doing that? The pulses get faster as the RPM gets faster.
Id try some of the other ports. Find one with steady vac n try it. I think the full n ported vac ports get confusing with so many of them. I had it back wards for a while. Still not 100% sure on which ones are which.
The larger port on the passenger side upper portion of the carb body is FULL manifold vac. The smaller port on the drivers side is ported. I'll try to find a pic..
Pic: Top left arrow is pointing to manifold vac, and the bottom right arrow is pointing to ported vac. On Edelbrock carbs, this is reversed. (I wish I would've known that 3 years ago!!)
I don't think so, it feels like at least one isn't. I've changed the plugs, wires, and cap, and it still runs rough. I don't have a compression checker yet. I had thought that I had a collapsed lifter but it seems to be working now, after replacing the pushrod. I hear a very audible "hiss", but it's hard to tell if it's coming from the air entering the carb, or somewhere else. I have to get a piece of hose and make a makeshift stethoscope tomorrow and see what I can find. (Thanks to whoever came up with that idea!!) :beer
I think the confusing part for me is my 80 Qjet has 90 ports on the front. The pic above looks cleaner.
:laugh: That's the bad thing about the newer qjets. That's a 71 in the pic. Get a compression test kit and run the test. You could have a burnt exhaust valve that is creating the miss. Do you still hear the hiss loudly when the air cleaner is on the carb? The carb will make a hissing sound when it's running, due to the fact that it's sucking air thru the top. Is the motor stock? What about your PCV valve?
The hiss is still there when the air cleaner is on, but it considerably less noticeable. The motor is a stock "71 Stage 1, but I'm using a regular air cleaner, not the ram air system. I don't know how old the PCV valve is, really ancient, I'm guessing, as the car sat for over 20 years without being driven, just started once in a while. The valves heads had a valve job done, when the motor was put back together in '81, but I guess anything is possible. The thing I'm most worried about is a broken ring, I don't want to have to pull the motor completely apart. I guess I'll know more when I get the compression checked.
My first thought was the PCV valve. Cap that off and see what happens. Sure hope that is the problem.
