Quote: Sorry if I left out some details. I had the distributor worked on in 2005 to have an advance curve limited to 14 degrees. 17 initial gave me 31 total. THAT was the setting I ran for 3 seasons with the '509 cam. Summertime I had to back it off 1 degree and stay out off the secondaries to avoid detonation. Heads are Edelbrock aluminum. 2" TTI headers. 10.73 compression. It had an average of 189 cranking compression with the '509 cam. The numbers should be lower with the Lunati cam I have now. This new cam has a later intake closing so I expected to have less of a chance of detonation. When I wrote 33 total, that adds up to 19 initial.
You shouldn't be pinging with only 33 total timing. There is something else at play here because your logic with the cam is sound as the higher lift + duration should help bleed off some of the compression.
FWIW, my build is loosely similar to yours as I have a Holley 4150 on a 10.4:1 499 stroker, same heads and even the same fuel pump! The big difference between our builds is that I have much less cam then you as in 484 lift or so. My motor idles like a stocker and pulls 16" vacuum in gear. Even with my wimpy cam, my motor won't start to ping until I hit over 36-38* total timing (18-20* base)! I run my motor at 17* base right now -- the first limiting factor being hard cranking on the starter motor if I go beyond.
FWIW, I had my engine tuned on a chassis dyno and I settled on 82/88 jets with initially a 6.5 PV but going to 8.5 helped out a bit on throttle response. This was with o2 sensors and it gives a nice flat A/F right around 13:1 at WOT (4000-5500 RPM range)...closer to the 14.7 at lower RPM's. Keep in mind this is with a 499. If anything, I think you may be jetted a bit rich.
How is the gas there? I think you either have crud for fuel and/or you are battling an overheating condition to make your motor so temperamental with the pinging. Maybe that or a vacuum leak but you would probably be able to detect that pretty easily. I suppose you could always limit the distributor's mech advance even further but that seems like a band-aid.
Maybe somebody who knows more about this that I can chime in. Let us know if you find anything.
