Zmedic

I am curious to how much timing I should be running in my car. I have an 80zx, with L28 , Triple webers, header, 280comp cam, E88 head has been milled and cleaned up. I know that I am probably running pretty high compression due to the E88 head being milled and put on an L28. I just destroyed my engine due to what I think is detonation problems I wasnt hearing. I know that there are several variables such as fuel, heat, etc.. But I am looking for a ballpark setting for my car. What should total timing be, and when should it all be in by? My cam comes in really good at 4000 rpm. Thanks in advance. Richard