I'm suprised you didn't hurt it worst than you did with that hot of a spark plug your lucky iit only burnt the ground straps off I would go to a non protruded gap and a #9 or#10 as already suggested. The last blower motor I work on dyno testing was a 484 C.I. 426 Street Hemi, it liked 33 degrees with 7 lbs of boost using a 10:71 Littlefield roots, no intercooler, running 12 % under on CA pump gas, that combination made 927 HP at 7300 RPM after doing a lot of small changes on it to sneak up on what it wanted. We got greedy (the owner wanted more) and switched the pulleys around to make it have 13% overdrive, switch it to race gas, back the timing down to 25 degrees total and made another pull, it started into detonation slightly at 6500 RPM and still made 1027 HP at 6500 RPM (we pulled it to 7500 RPM on all the pulls except the last one) I moved the timing up to 28 degrees total and ended up aborting the run wjhen it started to go into detonation again Luckily it didn't hurt it I switch the pulleys back and told him when you get it to hook up with the pump gas combination call me and we would hop it up again,I never got that call My meassage is back that baby down some to be safe and then sneak up on it Maybe some day, if I ever when the lottery or my ship comes in, I'll try a compressor on some of my own junk, twin hair dryers with intercooling and EFI