View Full Version : A Couple of Outboard Tune-up Questions

12-31-2005, 07:33 AM
I checked the spark plugs in my Johnson 20 HP & they are Champion 77's. I looked at Walmart and they had 76's & 77's, but there wasn't even a place on the counter for 77's. Am I going to have trouble finding these?

Second question. What is the stuff you guys put in the gas tank to get rid of moisture that condenses inside the tank? Will this help the motor run better next year when I get ready to go out again?



Barnacle Bill
12-31-2005, 07:59 AM
I use Sea Foam in my gas. It keeps water out and most of all helps prevent and removes carbon build up. As for your plugs, is there some letters that go with the 77. The old Johnson I used have used Champion L77JC4 plugs. Take it to a local auto parts store. They should be able to tell you what the new number is.

12-31-2005, 02:37 PM
Always put new plugs next to and side by side to old plugs to make sure reach is the same or new plugs may hit top of piston which is not good.

12-31-2005, 02:49 PM
IBNFSHN wrote, "The old Johnson I used have used Champion L77JC4 plugs."

That's the one. I didn't have my notes handy when I made my first post. But that's what they are. L77JC4's. And it takes two of them.

Also, where can I get "Sea Foam?"


12-31-2005, 03:01 PM
You can get Sea Foam at any NAPA store or other auto parts stores. It's a little price'y but well worth the money.

12-31-2005, 04:15 PM
Yes, I definitely agree with the SeaFoam additive. I have an 83 Merc. 35 and that stuff made her run like a new one. WOW!