[jpelli]

I have a 350 chevy with vacuum advanced hei ignition. The engine will ping like mad one time, than the next not ping at all. Have tried reducing the timing this didn't work, at a loss any suggestion?

[Not A T 25]

Originally Posted by jpelli

I have a 350 chevy with vacuum advanced hei ignition. The engine will ping like mad one time, than the next not ping at all. Have tried reducing the timing this didn't work, at a loss any suggestion?

I would try different gas if the gas you use is different from one time to the next the quality and octane rating could be different is the 350 stock? does it ping under load or at cruse and idol, You could also have a lean condition on your carb check your plugs to see how they read.

[jpelli]

I disconnected the vacuum advance and the ping is gone. don't know if I should replace the can or try to adjust it, although I can't see how it could change settings. Joe

[Not A T 25]

Originally Posted by jpelli

I disconnected the vacuum advance and the ping is gone. don't know if I should replace the can or try to adjust it, although I can't see how it could change settings. Joe

you can check the can utilizing your timing light to see how much advance it puts in when you hook it up, but the best way is to go by an Auto Zone or someplace like that and rent a vacuum test pump then you can check how much advance you get and at what in of vacuum. Check you vacuum lines for leaks also do you have it hooked to manifold or ported vacuum source?

[lamothe1]

Check to see if the small springs on the advance are in place. Maybe one came off and it's letting it advance to fast or maybe their the wrong ones (you can buy different size ones at Kragons and Auto Zone).