I need so help I have built a 383 with 10.5.1 flat tops with a 225-240 duration @.050 a edelbrock 1406 card and performer intake and this engine is pining. Timing is set at 14 degrees with out vacuum advance and it ok but I can’t get this thing to really move. If I plug vacuum advance it pings pad  

Does it ping at WOT or cruise or both. What octane fuel are you useing. Is it aluminum or iron heads. What is your total timing and when is it all in by. How much timing is the vac adding. I have a 383 with aluminum heads and I am at 16 initial 34 total all in by 2500. With the vac it is at 44. It comes in at 8" and is all in at 14". I use ported vac. If you don't have a dial back timing light get a timing tap on the balancer and see where you are at. If you are running lean with alot of timing it will ping a little easier. On the hiway at about 2800 RPM I am at 15.4 AFR and I don't get any ping on 91 octane fuel.