Best plug

[rob 135]

1973 Johnson 135 what is correct plug? I have QL16V now and it seems to load up at slow speed. Can I use the QL77JC4? Manual says UL77V but I am not liking the surface gap plugs.

 

[emdsapmgr]

The factory spec plug for that engine is the UL77V. Optional is the L16V. Most of the early crossflows used the surface gap plugs. They run just fine in these engines. I'd be running the UL77V plugs.

 

[F_R]

Well, for another opinion, I dislike surface gap plugs. But never mind that, the UL77V plug is fine for most running, including sustained high speed operation. However, the QL77JC4 will work better for lower speed operation or where fouling/misfiring is a problem. If it were my motor, you can bet it would have QL77JC4 plugs in it. In fact my motor DOES have QL77JC4 plugs in it (but it isn't a 135).

Don't be surprised if your QL77JC4 plugs look like crap after running awhile. That's the beauty of it, they can look like crap and still run perfect.

 

[rob 135]

I don't do any long periods of high speed . The QL77JC4 won't hit piston I hope? My surface gap plugs now look like crap now . If I run wide open for awhile they clean up ,but Idle to dock and check them and they are wet looking. Just want to see if normal plug will be better.

 

[rob 135]

I don't do any long periods of high speed . The QL77JC4 won't hit piston I hope? My surface gap plugs now look like crap now . If I run wide open for awhile they clean up ,but Idle to dock and check them and they are wet looking. Just want to see if normal plug will be better.

 

[rob 135]

I don't do any long periods of high speed . The QL77JC4 won't hit piston I hope? My surface gap plugs now look like crap now . If I run wide open for awhile they clean up ,but Idle to dock and check them and they are wet looking. Just want to see if normal plug will be better.

 

[rob 135]

Sorry for extra post . Not liking this new format. So many errors every time u try to post