Champion "Q" Spark plugs ?

Luna Sea

Lieutenant Junior Grade
Joined
May 20, 2002
Messages
1,069
For my 1985 120hp Evinrude the manual says use Champion QL77JC4 for "Sustained Low Speed/Normal Operations" For an alternate spark plug they list L77JC4, but they don't say what it's for. Is this the one you'd use for better high speeds/waterskiing? Basically, what's the "Q" stand for and has anyone had better luck with an NGK? (Or have the cross/ref no. to NGK)? Thanks
 

wilde1j

Vice Admiral
Joined
Apr 15, 2002
Messages
5,964
Re: Champion "Q" Spark plugs ?

I have the same motor, except it's the 140. The recommnded plugs are Champion QL77JC4 (Q is copper core, I think) and L78V. These plugs are almost the same heat range. One is surface gap (sustained high speed) and the other is conventional electrode supposedly for more low speed. I've used both with similar good results. The surface gap is no maintenance. There's no reason to consider NGK that I can think of. I routinely get two seasons from either plug.
 

almost retired again

Chief Petty Officer
Joined
Feb 9, 2002
Messages
438
Re: Champion "Q" Spark plugs ?

Hi Luna sea,<br />This is my advice, use the plugs that the manufacturer suggest ( Champions). If you use NGK's the engines power pack may pick up un-wanted RF noise. This may cause the engine to run very rough. The Q on the plugs that's in question says that it has an RF choke in it to help suppress the RF noises that can be generated by the plugs. The choke is nothing more than a small coil located in the porcelain portion of the plug. If you have an old plug, you can bust the porcelain and see this coil. I think that the Q comes from the Q designation given to coils which stands for the quality of the coil. Probly more information than you needed, but there you have it.<br />Good Luck
 
Top