Hey guys, I found this on another website: I tried doing this, but I can't even find these screws that this guy is talking about. My Carb number is: 17086590 if that helps. Anyone have ideas? My basic problem is that when I stomp on the gas, the car falls on its face, or stalls depending how hard I stomp on it. It's find on easy acceleration though, except when I hit a hill. I think that would fix the problem, seems that the mixture is too lean, but I just can't find the screws to adjust. o No:
Some pictures of your carb would help a lot. Here's some more reading: http://www.v8buick.com/showthread.php?t=103986 Devon
Ok, here is a picture. I found the slotted screw, but can't locate the allen screw. I tried turning the slotted, but its tight. Something is locking it. You can see the slotted screw in this picture. Edit: I think I might see the allen screw in this picture. Pff! Guess I just needed to stare at it for a little bit. I'll let ya know how I make out. Sorry for the size. Need to get some photo software on this thing.
Randy, This appears to be the later Q-jet. I beleive it was reffered to as the "mod quad". Maybe the allen is broken off or a torx srew was used instead. I think I have one of tese carbs laying around and I'll try to look at it. Bill
I tried getting something to fit the screw that Dale pointed out, but I don't have anything small enough. Took a mirror to it, but it's so hard to see. Is that what I want to loosen, to get access to the slotted? Thanks for the help guys.
Ok, Im on the right track now. I found the proper set screw. Its very small, behind the screw that Dale pointed out. Need to make a run to the store to get a bit for it!
Randy, Make sure the vacuum break is working. At idle, it should pull in the link to the airvalves. This slows the air valve tip in. If the vacuum break is bad, it can cause a bog. Also, check to see if the secondary rods are being lifted by the hanger. There is a small plastic cam the operates the hanger as the air valves tip in. Push the air valves in by hand and watch the hanger. Does it lift the rods?
When you release the set screw, have your slotted driver holding that screw steady. If I remember correctly, it will spin out of place quickly. It takes very small adjustments to fine tune the air valves. Imagine the slotted screw as the face of the clock. Only move in 5 minute increments before testing (you'll likely have to tighten and not loosen). What usually happens is the tension is too loose, and the air valves flop open quicker than the secondaries open. It's been a while since I've had a Qjet and had to tune the secondaries. The last time was after adding headers/exhaust, and an aluminum intake to my 71 GS455 (about 7 years ago). It turned out that they needed to be tightened up compared to the stock intake in order to remove the bog.
Thanks a lot guys. I'm sticking new plugs/wires/cap in tomorrow, and then I'll try tuning the secondaries if I see no improvement. The distributor cap is very bad. I had to cut off junk from the inside conductors.
It's unlikely that the secondary air valve is the root cause of your bogging--although it is possible. Be aware that there is a passive sort of "accelerator pump" on the secondary side, activated by air velocity past the front edge of the secondary air valve. If those tubes are plugged, you'll get a bog no amount of secondary adjusting will cure. Me, I'd also be wondering about the mixture control solenoid and the regular (primary side) accelerator pump circuit before screwing with the secondary air valve. Does the M/C solenoid respond to a vacuum leak; and does it respond to having propane inducted down the primaries? As filthy as that carb looks, you'd do well to at least pop the top off and blow through all the fuel passages with aerosol carb solvent, along with the previously mentioned check of the choke pulloff. If it were mine, it'd get a rebuild kit, a float, and a thorough soaking in carb cleaner. The LAST thing I'd do is adjust the air valve--after verifying that everything else was correct.
Hah, I was waiting for someone to say that! I am trying to hold off in spending any money in this carb, because I am planning on sticking another engine in it next year or so, along with a new carb. I might have to get a rebuild kit though. Thanks for all of the suggestions, I'll have to read up and try them all out. Thank goodness for my Hayne's manual.
