Have owned above stock (original) car 3 years. I always thought it was pretty quick. My son drove it recently. He said his 69 Grand Prix 440 would eat my car up for lunch, much faster!!! Crap. We were examing timing, dwell, etc. last weekend, (all OK) got around to looking into Seconday Throttles. Best we can figure the top Air Doors are not opening and if you hold them open, the throttle valve only open some and then seem to close back down. What should we look for, where should we start? The carb (a 0246) had a gas station rebuild right after I got the car. Could the tech have done something inside or at the base gasket that could cause this problem? Steven Sisson
The very first thing I'd check is to verify that the carb is opening all the way when you floor the pedal. Have some one get in the car and hold the pedal down while you look down the secondaries. The bottom throtte blades should be vertical. I bet you anything they are only opening 3/4 of the way or less. The secondary air flaps should be loose, but not "floppy" loose.
There is an adjustment for the secondary throttle blades. There's a tang you bend to make them open fully
If it has an aftermarket cam .....it could be way off, even if the dots line up. Always double check with a degree wheel. I have seen and heard of this with a lot of cars that are sluggish.
Ther eis also a lockout on the rear secondary throttle plates when the choke is on. On the pass side of the carb when warm make sure the lock ouit is not hitting. The rebuilder might have installed some parts wrong. Also as was stated and check the pull off make sure its not locking the secondaries out
First, The secondary air valves(up top) won't open unless the engine needs the additional air flow. You won't be able to get them to open by gunning the engine at idle. Even with the secondary throttle blades fully open, the air valves should slowly open as the engine needs more and more air. That is normal. The secondary air valves are slowed from flapping open by the spring tension (adjustable) and the primary choke/vacuum break on the front passenger side of the carb. If the secondary air valves open too quickly, it creates a bog. Second, just because your initial timing is correct does not mean the timing is fine. The timing should increase as engine RPM increases via the mechanical advance inside the distributor. This should be checked as it is common for the advance weights inside the distributor to be gummed up on an older car. That can sap a ton of performance from an engine. I recommend you read my power timing thread here: http://www.v8buick.com/showthread.php?t=63475
Q-Jets are not hard to work on once you understand how they work. Best place to start is to pick up 1 or 2 of these good Quadrajet books: Link to 2 good Q-Jet books
First, mentioning that your Buick was slower than a GP, could this be trash-talk? If it was, let's talk. First, carefully check the timing advances. The factory springs were strong, in order to slow the timing advance. They could use a freshening up, using an after-market kit. Before proceeding, however, you need to be sure that the advances are, indeed, working. Most of the older, mature vehicles could use a good cleaning at the advances. Check to be sure that they advance smoothly, and return completely. Be sure that you check this with the rotor installed, as many rotors I have found will cause a problem not seen with the rotor off. Also, for the most part, the initial timing can be advanced a couple of degrees with the factory advances working, but work carefully, and avoid pinging. All bets are off with after-market advances. Just work carefully. Also, as previously mentioned, check that the secondary throttles open completely, and that the air valves are demand operated. They will likely not operate in the driveway, with the trans in park, revving the engine. They can, however, be checked, using some common sense. With the engine off, and the choke ALL THE WAY OPEN, check that the secondary throttles open to the vertical, using the pedal, not the linkage. Wear, and the occasional bunched carpeting has done its share for my customers. Next, with the engine off, check that the air valves open relatively easily, return smartly to the closed position, and that the metering rod cam in between the air valves raise and lower the hanger COMPLETELY. Many worn cams either allow a lean mixture, or, if they do not rise, will create a severe bog. Let's start with that info, and go from there. Ray
