I just picked up my new-to-me '70 Camaro on Friday. On the drive home the car started pinging under heavy load (really hot day, heading up a mountain pass). I pulled off at the first rest stop and retarded the timing a few degrees. I didn't have a timing light, so I just used the calibrated eyeball method. The pinging went away, but I wanted to verify the timing numbers anyway. Today, I checked/set the timing using an adjustable timing light and digital tach. I set initial timing (no vac advance) at 10* at about 700 RPM. Centrifugal advance comes in at around 950-1000 RPM and is all in by 2000 RPM. Initial+centrifugal timing is 25 degrees at 2000+ RPM. Plugging the vacuum advance back in gives me 29 degrees of timing at idle and 45 degrees of timing at 3000+ RPM. These numbers don't seem overly high to me, but I'm still getting pinging under load (not WOT), though not as bad as the day I brought it home. It's been a while since I've worked on a car that didn't electronically control its own timing, and this is my first Chevy, so I'm a bit foggy about what ballpark timing for this engine should be. The engine is a GM 350ci crate engine (part #10067353). It's got a small cam and ~8.5:1 compression and uses HEI. It's got a two barrel carb and, I think, the stock 307 manifold that this car came with originally. Tranny is a TH350. The engine has about 70,000 miles on it. Despite the low compression, I'm running 92 octane. I would think that on an engine with this small of a cam, this low of compression, and running 92 octane that it would take a LOT of advance before it would start pinging. Am I wrong and simply running too much timing for this engine combo, or is there something else that could be causing the pinging under load? Is 10* initial too much? Is 45* total too much?