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sparkplug gap (AC Delco R45TS) for chevy 350 ?

10-30-2004, 08:20 PM
:banghead: Just purchased 1976 Chevy Silveraldo with a 350 4brl engine (engine came from a 78 corvette). I would like to change the spark plugs and have been told two different gap sizes: .034 and .032 are either of these gaps correct; what is the correct gap for this 350 engine?

10-31-2004, 01:53 AM
Both gaps would suffice, but I suggest expanding that gap to .040" and then pulling a couple after 10k. If they look even and bronzed, you're good to go. If your coil in the HEI is up to it, you could go as far as .050, but I'd stay lower.

I think that the standard gap for HEI 350s is .040, but its as easy as doing one of the following:

1) stop by your auto parts store and ask
2) look at your emissions sticker under the hood (your truck's gap would be the same as the 'vette)

Its not as important as you might think. In a race-only application maybe, but anywhere from .030 to .050 is fine for HEI. I'm running .038 in my 454 and .055 in my Caddy 500 with mods.

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