High RPM Studdering
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Joined: Jul 2005
Posts: 28
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From: Boaz Alabama
High RPM Studdering
I have developed a problem. My car ('79 L-48 w/ Quadrajet) has started to make a popping, small firecracker sounding noise when I get on the gas pedal. If the RPM's are low the car just accelerates, but if the RPMs are high then this noise, accompanied with a studdering/missing feeling, takes place. I thought maybe it was electrical so I replaced the plugs, plug wires, distributor cap and rotor. Also, replaced the fuel filter. No help.
I then decided to check the timing. The air filter was off and I was revving it up there at the carb while watching the timing mark. As I was revving it up I would give it about 3 or 4 revs to get the RPMs up (each rev increasing the RPMs) I noticed that on about the 4 rev the carb would pop on the "let off" portion of my rev ups. Also if I got the RPMs up and then held the gas there or increased the throttle steadily then I would get that sound irratically and continually, Only, if I didn't let off the gas (kept it at some high throttle) the sound seemed to come from under the carb (in the manifold???) rather than out of the top of it. Any thoughts?
I then decided to check the timing. The air filter was off and I was revving it up there at the carb while watching the timing mark. As I was revving it up I would give it about 3 or 4 revs to get the RPMs up (each rev increasing the RPMs) I noticed that on about the 4 rev the carb would pop on the "let off" portion of my rev ups. Also if I got the RPMs up and then held the gas there or increased the throttle steadily then I would get that sound irratically and continually, Only, if I didn't let off the gas (kept it at some high throttle) the sound seemed to come from under the carb (in the manifold???) rather than out of the top of it. Any thoughts?
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I'm thinking that it could be a vacuum leak, perhaps the base gasket under the carb. My other thought is the float bowl level is too low. Good luck!!
