Spark Plus Gap 1975
#1
Melting Slicks
Thread Starter
Spark Plus Gap 1975
I have a '75 Convertible with a 350 carb engine. Going to change plugs this weekend and need the plug gap information. The Chilton Manual says .060 for the1975....but all the years before and after shows either .035 to .045. WHICH ONE SHOULD I USE????
#3
Safety Car
but was that .60 just because it was the first year for HEI and they learned and revised the gap for the following years that used the same components or is their something unique about the ignition system on the 75? if so what is it? the OP's ignition / distributor system does not appear to be original either so Not sure if the stock specs even apply here?
#4
Le Mans Master
I've been running .050" in my 77 with HEI and it seems to like that. I believe my manual also say's .060" , That's a bit much IMO may encounter misfire at high RPM or with highish compression. If it's stock it'll probably take it.
#6
Racer
but was that .60 just because it was the first year for HEI and they learned and revised the gap for the following years that used the same components or is their something unique about the ignition system on the 75? if so what is it? the OP's ignition / distributor system does not appear to be original either so Not sure if the stock specs even apply here?
#7
Le Mans Master
The wide gaps are to improve performance with leaner emissions mixtures. The wide gaps were required to fire the crappy, harder to reliably fire mixture....the HEI was required to fire a plug with a wider gap.
#9
Le Mans Master
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I've read an awful lot on this subject. And I second the .045 recommendation.