got pinging

[Nacho-RT74]

hey you wrotte 30º iddling ? LOL

some of your data posted is a little bit confusing LOL

I got a equus timming light with tach in $63 from amazon ( tired to need the ppl around to anything ), just still not shipped from my courier service in Fl to home. Still waiitng to get all what I need to make a larger shippment

[flyinlow]

A ballpark figure for a BB Mopar with an AUTOMATIC TRANSMISSION would be 36* BTDC by 3000 rpm and above. You might be +/- 5* of this number depending on your exact build. I have all the centrifugal advance in by 2600 rpm. These numbers are with the vacuum advance disconnected of course. If your pinging is with the vacuum advance functioning you might try adjusting the vacuum advance unit , adjusting how much vaccum is required for full advance. I limit the advance on mine to 8* by limiting the stroke of the advance unit to prevent pinging.   

[Nacho-RT74]

nice info

last night arrived to 4100 RPMs on WOT and got no pinging.

Now I'm wondering... isn't better get more compression before ignition to a bigger explotion? if so, shouldn't be the ignition timming closer to TDC ?

just wondering in the middle of my ignorance

[flyinlow]

I am ignorant too. I have done a few 440's and 383's over the years, still very much an amateur. If I understand the question, high compression will make more power than lots of spark advance. If you had two 440 Magnums , one a 1968 with 10:1 CR and 175 PSI cranking compression , the other a 1973 8:1 CR with 140 PSI cranking compression pressure, why does the 1968 engine make more torque? Durring the compression stroke all the way until 36* BTDC the higher compression motor is losing more energy from the crankshaft to compress the airlfuel charge. Now at 36* BTDC both engines ignite the cylinder (3000 rpm WOT). The cylinder pressure raises fast with peak pressures and combustion compleat somewhere around 10-20* ATDC. The high compression engine will have higher post ignition cylinder pressures and may complete the combustion process faster. This is where the higher compression engine pay back is. If tuned for best power , the low compression engines I have worked with can run more centrifugal advance (38-42*) and this does help them make more power , but they can not match the efficiency of the higher compression engine in making torque.

This a very generic comparison. Cylinder head choice, piston choice, quench numbers, cam choice and other variables would all effect the comparison.

Wayne's engine tuning video that came out a year or so ago had a lot of good info on these choices.