Mine won't start if the plugs are wider than .035", Doesn't run as well at .032 as at .028 to .030, but then mine has 11;1 compression, So that's how I do it on all the cars. Open 'em up till they won't start (cold), then back 'em down .oo5". Maybe I'm nuts, but the '77 gives me 32MPG at a steady 70. Well, OKAY i AM nuts.....