Questions and Answers
Firebird Won't Idle Down
Q. Hello, I've got a question about a problem that might be caused by a vacuum leak. I have a 1968 Pontiac Firebird with a 326 engine (not original to the car) and a TH350 transmission (also not original). It's got a quadrajet carburetor, and there are 180,000 miles on the car. (I'm not sure how many miles the engine actually has on it.)
I've replaced the intake with an Edelbrock performer manifold and replaced the points type distributor with an HEI unit. My problem is that when the car revs over 3,000 RPM the engine only drops down to idle at 1,500 RPM (instead of the 500 RPM it's supposed to idle at). Are the secondaries staying open on the carb? When I shut the engine down and start it up again the engine idles normally. Are there any other types of vacuum leaks other than hoses (possibly from the intake or headers). I'd appreciate your help.
Darrell
A. When it's running at 1,500 rpm's is the carb linkage on the idle stop screw or is it not returning all the way? Possibly cable/linkage is too tight? Or a weak return spring? Carburetor could be holding vacuum to secondaries. If you suspect vacuum leaks, they can be found by carburetor cleaner sprayed around suspect areas watching for idle speed changes.
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