Bill, I've got a 350 in my 72 Chevelle with HEI. It was not original
since the HEI appeared in GM motors in 1975. But the spark plug gap for
HEIs for years 1975 and later is either .045" or .060" depending on the
plug type and heat range. AC plugs with the number "AC R45TS" or their
equivalents are .045" gap, while the "AC R45TSX" is gapped at .060" so I
hope this is of some help to you. And you are right, the .035" gap is
pretty standard for GMs with breaker point ignition.
Wally / Templeton, MA
53 3100 rod project
72 Chevelle Malibu
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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