Spark Plug Gap: Points vs. HEI Does It Matter?

70lt1z28

Veteran Member
Gold Member
Oct 3, 1999
4,869
Beavercreek, Ohio, USA
Also keep in mind the motivation for large gaps back in the mid 70's was the excessively lean mixtures they were trying to run due to emissions. To light off the lean mixture (not as many molecules of gas floating around) the spark had to jump a big gap. If you are not running a lean mixture (why would you be), then there is really no advantage to running a large gap, and it could be a disadvantage as it tends to stress the weak links of the ignition system a bit more.
 

Z28PILOT

Veteran Member
Lifetime Gold Member
Oct 8, 2009
2,313
Emerald Isle , NC
Lol …man …..I had to think hard about the gap of the plugs in my 74 L82 w /GM HEI , I have only put one set of plugs in it since sept 2008 . I found a note in my owners manual indicated I set them at .045 gap.
 

mallard

Veteran Member
Oct 3, 2013
1,956
SK, Canada
Lol …man …..I had to think hard about the gap of the plugs in my 74 L82 w /GM HEI , I have only put one set of plugs in it since sept 2008 . I found a note in my owners manual indicated I set them at .045 gap.
IIRC, some very early HEI models were recommending plug gaps anywhere from .060 up to .080 in Oldsmobiles.
 




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