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Spark plug gap autolite 45s

Bronco Sully

Full Member
Joined
Oct 31, 2012
Messages
293
Loc.
Houston
Replacing the old autolites with new ones in a few minutes. See sig below, stock 1973 302.

I think I've see .035, correct?

Cheers, Sully.
 

johnbeck

Sr. Member
Joined
Aug 11, 2015
Messages
534
I too have a stock 73 bronco 302 with autolite 45 plugs. I replaced the points with a petronics electronic points. Should I change the spark plug gap?
 

B RON CO

Contributor
Bronco Guru
Joined
Jun 29, 2016
Messages
2,334
Hi, with a pertronics points replacement and a pertronics flame thrower coil or any other hotter coil you should open up the plug gap to probably .045. A more efficient ignition can run a larger plug gap. Good luck
 

Broncobowsher

Contributor
Total hack
Joined
Jun 4, 2002
Messages
33,458
Higher power ignition, more gap
Higher cylinder pressure, less gap

I take it you are running a streetable compression ratio and running pump gas, your cylinder pressure has not changed enough to really worry about. If it were an 11:1 engine I would drop the gap a couple of thou. Probably .001" per point of compression. But that jump to electronic ignition is good for about .010 over stock.

The wider the gap the better, until it doesn't fire. That shows up while starting and/or under high loads.
And over about .050 you start burning up the center button on the cap from excessive heat.
 
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