spark plug gap
#1
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Just bought new plugs, and they are gapped from the factory at 42 thousandsths. Mercruiser suggests 32 thousandsths for my 420 hp engines. how important is regapping the plugs?
thanks.
thanks.
#2
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Are you using Merc ignition & coils? If so, I would gap them at no more than .035. A larger gap, provided you have a "hot" coil produces a larger flame front for more complete combustion. I used .040-.045 on my Jacobs ignition w/MR43T plugs in my blower motors and worked extremely well.
#3
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Using merc thunderbolt ignition. Noticed that the 330 was at .035, and the 420 was at .032. Seamed a little odd to me that the lower hp engine would use a larger gap.
looks like a gappin we will go. . . .
looks like a gappin we will go. . . .
#9
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Originally posted by Sammy
I'm runing a SBC putting out around 360-370 hp. Griff, " they" are NGK .
Sam
I'm runing a SBC putting out around 360-370 hp. Griff, " they" are NGK .
Sam