Indexing plugs ??

WOW, that's a more significant impact than I expected.

It's a 9:1, .030 over 360 with a dual pattern 455/475 cam, and the usual list of good mods (FBO ignition, intake, 4 barrel, electric fuel pump). The motor has less than 1500 miles on it.

Guess Summit or Jegs has the index tool and spacers......(time to go shopping).