Plug Gap L77JC4

87Aggie

Petty Officer 1st Class
Joined
Mar 29, 2004
Messages
256
On another topic I learned that the ..JC4 plug was alternative to the surface gap UL77V plugs that I've been using on my '77 Johnson 140 hp. Can anyone tell me what the correct plug gap should be?
 

Walker

Captain
Joined
Jun 15, 2002
Messages
3,085
Re: Plug Gap L77JC4

Some recommend up to .040, but I gap all mine at .030 for the crossflows and loopers.
 

87Aggie

Petty Officer 1st Class
Joined
Mar 29, 2004
Messages
256
Re: Plug Gap L77JC4

Thanks for the response Walker, I've got it gapped at .035 now. Using the ..JC4 plugged seemed to improve my less than desirable idle I was having with the surface gap plugs. You think gapping at .030 will improve the idle even more?
 

Tom Scully

Petty Officer 2nd Class
Joined
Oct 14, 2003
Messages
154
Re: Plug Gap L77JC4

Do a search but I believe .040 will give you a better idle.
 

npd4432

Chief Petty Officer
Joined
Apr 18, 2006
Messages
468
Re: Plug Gap L77JC4

Recommended gap .030 for high speed and normal operation. .040 for excessive trolling. Recommended plug is L77JC4 without VRO QL77JC4 for VRO motors. I use the QL77JC4 on my '83 without VRO gapped at .030
 

87Aggie

Petty Officer 1st Class
Joined
Mar 29, 2004
Messages
256
Re: Plug Gap L77JC4

As Walker said, I'm gonna give .030 a shot. As stated above, I'm currently at .035 - seems like .005 wouldn't make that much difference, we'll see. Thanks again ya'll for the info!!
 
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