Timing issue (pinging) solved!

[TrybalRage]

Just wanted to share what I've been dealing with to hopefully help someone else out who ever runs into the same problem.

I've been dealing with a pinging issue for a while, one that I've ignored by dialing my timing back to 2-4° BTDC. I was starting to think that everyone was nuts, talking about setting 10-14° as their base timing. Around town my truck was fine, but I moved recently to an area with a lot more hills, and I've had to do quite a lot more highway driving. Up those hills I'd start to ping, and have to back out of the throttle further and further to avoid it to the point I was barely crawling up the hill. On the highway I could cruise along all day, but if I had to pass someone, forget it.

I've been running with a Skip White distributor I bought after the ESC went bad on my factory one and I just wanted to go to a "normal" HEI. Initially I had my vacuum advance run to a 'ported' line but after much reading, I started running it off of manifold vacuum. For a long time I thought my pinging problem was the adjustable can that the distributor came with.

I've been playing with timing, swapping out vacuum cans to the original, and doing a lot of reading on here and other sites. Finally I decided it was time to get this fixed.

Bought a piston stop and verified TDC. The marker on my balancer was within a degree or two. Stuck a timing tape on there to better track my numbers. Disconnected my vacuum can and increased the idle to make it drivable and started testing. At 10° initial, I was still getting horrible pinging at medium-heavy throttle under load. WOT was fine, no pinging. Ok - maybe the springs are too light, advancing too early. Had picked up a Mr Gasket recurve kit so I started putting in heavier springs. Started with the medium - no go. Still pinging. Put in the heavy - nope, still pinging. WTF. Everything I've read says if I verified TDC, set to ~10°, heavy springs should be too slow of an advance, but here I am, still backing out of the throttle on hills.

So I started looking at my factory distributor. The springs. The weights. How it all came together. Looked back at the dizzy in the truck and realized that the Weights seemed to be very "loose". Checked timing again and realized that with the heaviest springs, the first tap of the throttle was still advancing the timing by 7-8°, at least. Took the cap off again and saw that the weights were able to move outwards quite a bit before the springs ever even limited their travel (this is with the weights it came with).

So even though they looked different, smaller, I took the weights and bushings from the recurve kit and put them in the distributor. Almost no play. Kept the heavy springs, and took it out for a spin. No more pinging! Reconnected the vacuum advance (the adjustable one the Skip White came with), still no pinging!

So it turns out the weights it came with were pretty sloppy, allowing advance to happen before it was supposed to, causing a lot of under load/middle throttle problems. I still have some tuning to do, I think I can drop the heavier springs for some lighter ones, and adjust the vacuum can a bit, but I finally feel like I'm on the right path.

Hopefully this helps someone out there, and thanks for everyone else who posts their advice and tips (Rich's distributor insight is invaluable, BTW).