I have a 350 caprice motor with an aftermarket cam(not sure on the specs) and stock 305 intake and injectors. I was getting a custom chip burned and we noticed that any time we would put into the motor, it would ping like crazy. We have been battling for this ping for a while now and can't seem to get it to work out. My car has always pinged a little in fifth, but the chip made it worse. The a/f ratio was always right on but the pinging was non-stop. We finally ended up @ 1-3 degrees advanced and kept the a/f where it was when the chip was first burned. It still pings a bit but not sure how to fix this. Anyone have any ideas?

The car is in good tune(plugs, wires, etc.) and has an open element.

Thanks,
Brandon

 

Did you make sure your base timing was set at 0?

 

yeah, we were baffled every time it came to 0. The motor just pings like crazy with any timing.

 

Have you outruled a slipping harmonic balancer?

 

The short term fix is to get a 89-90 Caprice copcar chip together with injectors from a copcar 350 or a C/K/G truck or van 350. That and making sure that the base timing is set to zero degrees while you reset the distributor position with the ESC wire disconnected. It will probably run a lot better than what you currently have.

You are pinging because the ignition is all wrong, you have a aftermarket cam that has slightly different ignition needs, and you are running lean at anything but idle. A band-aid fix is to raise the fuel pressure, at least until you can get the proper injectors and a better chip.

Factory TBI Caprice had swirl port heads that needed zero degs at the distributor (because they're fast burn heads), so zero deg is optimal for factory tuning and 87 octane. The chip used in the 89-90 should work in your Fcar (8746 ECM if I recall right), and it will have minimal pre-programmed ignition advance within it, which is exactly what the Caprice wanted. It's also a better fix than just raising the FP alone.

THAT is where you should start. Any aftermarket chip you use ought to start from the 89-90 Caprice LO5 copcar specs and then be adapted for use with the aftermarket cam you have installed. HTH.

EDIT: you'll probably also need a new fuel pump depending on what the cam is.

 

As long as he's running the stock fuel pressure, the stock pump will be just fine. I would say pretty confidently that it can handle the stock fuel pressure (9-13psi) with the injectors totally static. Now, whether or not that's enough fuel for the engine is a different story.

An aftermarket cam is only going to want more spark advance, so something more advanced thatn 0° BTDC is acceptable, imo, but obviously it will need to have its fueling needs met.

 

Well, heres what was done. We started with the 350 cop chip. It pinged like crazy. We saw that the fuel was a bit rich, and was pinging a whole lot. We backed out the timing, and some of the fuel. WE had the a/f right on but it still pinged. The more timing we took out the better it ran. Once we had gotten to the point where it did not ping very much, we were @ 1 degree advanced. It's basically the stock chip, 1-3 degrees advanced, extra fuel, and the speed limiter deleted, etc.

It was rebuilt 10000 again so i don't beleive it's teh balancer.

I don't see the need for bigger injectors or fuel pump right now if the a/f is right on.

I have set timing before and am confident it still set @ 0, or close to it.

I have the l05 heads and the timing is set @ 0.