What would cause a vacuum gauge to flutter? My motor is a ford 302, duraspark II distributor, mild cam. Typical mild ford. I recently moved the vacuum to the distributor advance from a port on the Eldebrock AFB carb, to a port on the dual plane intake. I adjusted the distributor and carb using the vacuum gauge. Now, anything off of idle in park causes the vacuum gauge to flutter so bad that it rattles. I've never had this issue before. The only change was moving the vacuum on the distro to the intake manifold. The vacuum gauge is hooked to the same tree on the intake, in the same position. Is this an indicator of something wrong?
Isn't ported vaccuum from a carb different than manifold vaccuum? I know you can't do it on the old 94 carbs on flatheads. Just a guess.
Va***e flutter can be caused from several possible issues First thing I would check is put the va***e back where it was If flutter goes away then you need to decide if want to leave alone I would bet that is not the case Usualy a flutter is caused by a valve issue Possibly sticking valve or lifterbuilding up holding valve off seat Burnt valve It could be as simple as spark plug wires crossed But I would have to say just moving the va***e advance from Port to intake va***e will not cause flutter It was probably there before But is it possible a couple plug wires came off and got crossed Just thoughts Ray
The vacuum for the distributor should not be connected to the intake vacuum. Put it back on the carb.
Thanks for the replies guys! The carb is a eldebrock AFB 600 CFM. The vibration is very slight, less than one incriment on the gauge, but it causes it to rattle. One the carb, the drivers side front port is suppsoed to be open, but it only goes up to 10inches, and the right one only shows any vacuum at almost full throttle. Is that right for this carb? I had read somewhere that some engines respond better and run cooler pulling the distributors vacuum from the intake port. I'll move it back in the mean time.
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