HEI Mech advance spring help/timing adv advice

[greywurm]

I am trying to think through an issue I have with some combination of timing, mech advance and vac advance. Hoping you guys can help me out troubleshooting this... I am leaning towards a mech advance issue, but I really dont know a lot about it.

Specs: 350 sbc, edelbrock 1406, aftermarket intake, hugger headers, true dual exhaust with black widow mufflers, HEI, TH350

I have had the initial timing set around 14 degrees as this seemed to be a happy medium between initial and total (I dont remember where total timing fell). But I was still noticing a bit of a ping coming out of the exhaust when letting off the throttle going downhill on the highway (engine almost at 3000 rpm).

Being that I also felt like I am lacking some power, I decided to throw caution to the wind and time to 36 degrees total (vac can plugged) and see what it would get me. This brought initial timing at somewhere over 16 degrees.

I have a short hill close by, but its a little short and in a residential area so going 80 isnt good, so I threw it into second to get the RPMs up at a lower speed. As expected, the pinging through the exhaust is a lot more frequent and wont stop until i put the trans into 3 to drop the rpms down.

Now, I am thinking since I either have to have too little total timing or too much initial timing that there is something wrong with the mech advance, like stuck or worn springs. Problem is, I really dont know what I am doing or what I am looking for, so would need some advice from you guys.

Also, I dont know how to test the vacuum advance can to see if its functioning properly. I did a couple runs with the vac adv in ported vac and manifold vac ports on the edelbrock carb... Not really any difference in the pinging, but it always idles better on manifold.. i've also read that ported is garbage and an early emissions trick from the 70s.