1975 Johnson 70 HP what plug?

[chilkoot]

Hello Guys,
first, congratulations to the great site and community! I'm new here, writing straight from Hungary, please help me out.

Dad bought the above outboard engine last year, second hand, no manual. Today we put it on water, seems like one cylinder doesn't work. The engine has some strange eastern european plugs, could you please tell me what sort of champion plugs we need to buy for it and what gap we should use? Also what gas oil mix is appropriate?

I cannot tell the engine's model number if it is important I will visit dad tomorrow.

thanks in advance
chilkoot

 

[tashasdaddy]

Re: 1975 Johnson 70 HP what plug?

champion 1975 - 1989 L77JC4 or QL77JC4 gapped .030 QL is if you have electronics, or radio. fuel oil mixture is 50:1 use TC-W3 rated outboard motor oil. before buying anything, check the spark on all 3 plugs, if one is failing, swap the coil completely, with another coil that was working, if the failure follows the coil, replace the coil. never hurts to run the correct plugs. model # is always important, that way you get the best info you can. look for a plug like this, should have model and serial #.

 

[chilkoot]

Re: 1975 Johnson 70 HP what plug?

Dear Tashasdaddy,
thank you for the quick reply. We are gonna buy the plugs and oil this weekend, as soon as I see the result will post update.
regards
chilkoot

 

[chilkoot]

Re: 1975 Johnson 70 HP what plug?

Update 1.
Dear Tashasdaddy,
luck does not seem to be in our team this time. First of all, thank you for the advice, spark plug and gas-oil mix worked great. We put the boat on water, for a while it went smooth, engine lifted the boat out of water nicely, then again, it lost power like one of the three cylinders would have stopped then reignite again. We checked the plugs and all of them looked good, no greasy stuff on any of them. Then we pulled the boat out of water and left it for the day, next day (still out on the dry) Dad started the engine to check something, (engine ran for a sec) then we noticed oildrips from the lower part, where the pulley and the lower par of the engine meet. Sorry for not knowing the correct terminology. Do you think we should take apart the under-water part of the engine? And if so, how should we start? does dripping mean the engine needs new sealing somewhere? Friday I will go and take some pictures to show the correct situation.
Thank you for your help again,
have a nice day
chilkoot

 

[clemsonfor]

Re: 1975 Johnson 70 HP what plug?

That oil is likly unburned gas oil and water mix driping out if black if it smells like rotten eggs its gear oil and need to be changed and figured out where it is coming from. If it is just black oil sludge dont worry. Also never run an out board dry it will burn up the impellor (water pump) use flusher muffs or a barrel or leave it in the water. I think you possibly have a coil failing or plugged carbs, id pull the carbs and rebuild them anyway if not been done and motor has sat for years like you say.

-nate