20 hp Johnson Outboard Spark plug help

[moemoe]

Hi guys, I have a question for you, I am going to to my wifes family's cottage this weekend and they have a motor, a 20 hp Johsnon that hasn't been run yet this year, I was hoping to bring up some new plugs for it, anyone know the model of plugs? I know, I know, noone knows the exact year but my guess would be late 80's to early 90's, Thanks!

[2 tone z71]

Champion QL82C work for ya

[Mark Bleau]

I just checked my shop manual and it says QL77JC4 and gap is 0.040

[2 tone z71]

http://www.dixiemarinesales.com/Spark_plug...n_Evinrude.aspx

[moemoe]

Thanks alot guys!

[chinookhunter]

no the gap is .0044

[boatman]

Both Champion QL77JC4 and QL82C are fine. The former was the original recommendation. I don't know if they changed to the hotter QL82 after they dropped the oiling ratio back down to 50:1 from 100:1 or not, but if you do a lot of trolling I'd get the QL82's. If you do more WOT running then perhaps the QL77 is best. Either is fine. Plug gap is .030".

[jeffw]

I have a 93 20hp and runn the 77 with good luck. Partsources carry them aswell as ct. Don't run the ngk's they foul like crazy on those outboards for some weird reason.

Cheers Jeff

[moemoe]

A question, and honestly I don't know, but how do you know that the QL82's run hotter and why is that better for trolling? Because I do like to troll

Edited September 10, 2009 by moemoe

[2 tone z71]

hotter plug @ Ignition = less fouling ,burns more of the mixture

[boatman]

A question, and honestly I don't know, but how do you know that the QL82's run hotter and why is that better for trolling? Because I do like to troll

 

For Champion plugs (like most, but not all spark plugs), The higher the number (in this case 77 vs 82) the hotter the plug.

Edited September 10, 2009 by boatman