[blkstangcon1985]

After discovering I have E6 heads and putting the correct plugs in as well as a tune-up and new gaskets ect...it sure runs great...One thing though..I took it on the freeway, got it running warm, mid-way through thru the temp. gauge, then got off freeway sitting at a light. When I began to takeoff there was some knocking for a few seconds. Are the E6 heads higher compression than the original E5 which came with this E5 block? I am running 87 octane in it..should I be running 89 or 91 to prevent knocking when it's hot??

Thanks

[GTRaptor]

I think a mix would leave some margin, remove -1° advance and use 89 octane.