Timing Question

Not sure what you mean with "the slotted bar is marked 15" but you mention at idle the timing light says you have 32 degrees advance. I assume this is at around 700 - 800 rpm correct? That would be way too much initial advance and it would surprise me if you didn't have any problems getting the car started without any starter kickback.

Are you sure the timing mark on the dampener is correct? Just make sure the dampener hasn't slipped by checking if the 0 mark on the timing tab matches up with the groove on the dampener while the number one cylinder is at Top Dead Center (TDC). If you want to make absolutely sure it is correct you could use a piston stop.

The initial should probably be more like 14 degrees at idle and around 32-34 at full mechanical (2200 rpm). Have you tried setting the mechanical timing to 32? You can do this by bringing the idle RPM up to 2200 rpm (your full mechanical) and then set the timing to 32 with your timing gun.

Running the vacuum canister helps out with getting better fuel mileage during part throttle (high load). It ads timing when the manifold vacuum is high (part throttle) to help out with a better combustion. It also helps out with a part-throttle bog where the engine needs more timing before the full mechanical has come in. But since your car is pinging at low rpm, you already have too much timing in so adding the vacuum advance would only add to the problem.

Have you tried setting the timing not with a timing gun but by the highest manifold vacuum reading at idle (with the vacuum advance blocked off)?