Help with Pinging

[gojo64]

69 charger, 383 mild street car, auto, MP distributor (bought in 2001), 2400 stall converter, 3:55 rear, 93 octane summer gas. Car warmed up to op temp, I set the initial timing at 15 degrees (approx. 900 rpm) with vacuum advance unhooked & plugged (& I kept it that way), not sure what mechnical advance timing is at this point. It runs real good & starts up quick & easy, but pings slightly when going up hills or under light load partial acceleration. What can I do to stop the pinging? How do I check the dist. mechanical advance? When I take the cap off, I see a torx head screw on the plate, how do I adjust ? Firefighter, Chryco anyone, any thoughts? Thanks in "advance" , no pun intended 

PS: also, when I have a vacuum gauge hooked up to manifold vacuum, it's approx 12", but it's slightly fluctuating 10-14", is this normal or is it something bad? Everything is new top to bottom.

[Chryco Psycho]

Vacuum is in the low / normal range depending on cam & intake
to cure the pinging you need to either back the timing off slightly or use better fuel
the adjustable advance limits the total advance so reducing the timing curve more, this will require more advance at idle to get the same total advance which is not what you need & will add to the pinging problem
you may need to adjust the vacuum advance unit on the dist , turn the adjustment screw all the way countervclockwise & turn the screw in again 1-2 turns & connect the vacuum to get the curve you want with maybe 13 * at idle & still have 36-38* at 3000 rpm

[firefighter3931]

Check the total advance and see how soon it's coming in.....the curve could be causing the detonation issues if it's coming in too soon and if there is too much total advance. Use a timing light and map out the advance in 500rpm increments and report back. The newer MP distributors are adjustable for mechanical advance and the springs control the rate of advance. 



Ron