So this is the deal. As some of you may remember, I just had my 390 rebuilt and it dyno'd best with the timing at about 36 degrees adv. at 2500 rpm. Since I got it in the car I have been having some detonation issues. I was running 92 oct. (which is what I used at the dyno) and in the car it runs great but when I put it under some load it has what I am calling detonation. I have lower the timing a bit to about 34 degrees and I have used the NOS brand octane boost. Still getting the detonation. Yesterday I went to the local airport and put in 6 gal of 100 octane with the rest of the tank filled with 92. I am still getting the noise but it is not as bad. So should I go to a 50/50 mix or try lowering the timing more or is there something else anyone can suggest? I have run it with the vacuum advance disconnected and still getting it. I have this great new motor and I can only run it about 1/2 to 3/4 throttle so I want to DRIVE my car not just put around in it. HELP! Thanks, Keith Evenson -------------- next part -------------- An HTML attachment was scrubbed... URL: http://splatter.wps.com/pipermail/amc-list/attachments/20080624/b2b9f8fe/attachment.htm _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://splatter.wps.com/cgi-bin/mailman/listinfo/amc-list