Where would a good starting point be for gap on a 421 sbc, with dart 15* heads, 48cc chamber, on C16. Motor was built to run NA, went 9.20's, changed converter and running 8.50 index now. With an NX fogger using there jets that say 300hp, 31n, 24f. what should/would a good starting point be on the plug gap?? posted in wrong section originally..