Re: Best spark plugs for '75 Johnson 115hp?
For your engine, the factory recommended spark plug is as mentioned above, the Champion QL77JC4 plug, and I recommend the original factory suggested gap setting of .040.<br /><br />A alternative s/plug was the Champion UL77V surface gap plug (no set gap). However this type plug, although the heat range is listed as "77", it actually has no heat range to speak of and fouls quite easily on some models.<br /><br />(EDIT 01/06/05) However, it has been brought to my attention by OBJ (Post Listed Below) that a bulletin exists pertaining to a Champion QL16V. Somehow the knowledge of this plug had escaped me but OBJ graciously saw to it that the bulletin was delivered to me via email.<br /><br />As OBJ suggests and from what I've read on the bulletin, the QL16V (surface gap) spark plug is an acceptable alternative spark plug for the engine as posted in this thread.<br /><br />Your choice.... try and decide.
