my engine is 10.3 comp, i run it on 91, and i have retarted the timing several times and still get pinging. it will only ping when the tranny is locked up in od

You're getting a low-load, low rpm ping that probably can be tuned out.

First things first, get your vacuam cam off ported and onto full manifold vacuam. make sure it works right... pull the hose with a timing light on it and see that it retards, right now.

With the can on manifold vacuam, you'll get more advance at idle and low-load, it'll run better with the initial retarded more.

Get your vacuam guage inside the car where you can see it, and drive. You need to see where the vacuam guage is when it pings.

Then it's time to work on the power enrichment. What kinda carb you got? For a holley, put in a power valve that opens at a slightly higher reading than the guage shows when it pings. For an edelbrock, same, but with the power piston springs. With the edelbrock, you can also change metering rods to one with smaller diameters.

If that doesn't get it, get an adjustable vacuam can, and tune it so the advance falls off quick when you get into the throttle a little.

all else fails, once apon a time, I used a water injection system with an adjustable vacuam triggered controller to squelch a similar situation.

Another option I've never tried would be a controller that will release the converter at the slightest drop in vacuam.