Help! Engine Sputters & Chugs at low RPMs

[Elliott]

In the last several hundred miles my 79 corvette has developed a sputter & chugging when starting from a stop or at low rpms. It doesn't pause or jerk like when an accellator pump fails; just sputters and doesn't run smooth as it used to. If I throttle up the engine it goes away and still performs well going down the highway. Yet even cruising at 25 - 30 miiles/hour and touching the pedal causes it to sputter. I believe it has a quadrajet carb. My mechanic has adjusted it and doesn't know what else to do other than to try another functioning carb to confirm it is the problem. His experience is that these carbs are real sensitive and neither of us are convinced we want to spend the money to rebuild it . . . yet. Anyone have any suggestions or similar problems? Elliott

 

[tracksnblades1]

Have you verified your power valve has free movement, with the engine off? This can be done without disassembly, don't damage it. Check to make sure both squirters are squirting healthy streams. Good luck.

 

[Elliott]

I will certainly give that a try. Thanks for the input!

 

[Elliott]

I will certainly give that a try. Thanks for the input!

Turned out #6 cylinder spark plug was fouled. Changed the plug and it runs like new. Pretty sure my valve stem seals are leaking and will have to see over time if that is what caused the fouled plug.

 

[Hib Halverson]

If your engine has valve stem seals leaking bad enough to foul plugs, it's time to overhaul the engine.

 

[JohnZ]

Have you verified your power valve has free movement, with the engine off? This can be done without disassembly, don't damage it. Check to make sure both squirters are squirting healthy streams. Good luck.

Q-Jets don't have a power valve - I think you meant accelerator pump.