Spark Plugs for 1974 50hp Evinrude #50473

[mstone1968]

Hello,
Could anyone tell me the appropriate spark plugs to use for this motor. I have had trouble with the motor running properly and put new spark plugs in, However, i put the same size/kind that was in there when I bought the boat. We finally figured out that the motor is only running on one cylindar. The guy that was helping me work on it looked at the spark plugs and said they were not the right type for this motor. I can't find any kind of chart that says what the appropriate spark plug to use. We took the ones he had in his motor (80's model 40 hp mariner) and they seemed to work, but I just want to make sure that I am using the correct one. Thanks so much for the help.

 

[ezeke]

Re: Spark Plugs for 1974 50hp Evinrude #50473

Check here:

http://www.boatsetup.com/SparkPlugChart.pdf

The QL77JC4 set at .03 will probably be best all-around.

Check the spark with all plugs removed. If you get spark in all of the plugs, then you probably need a stronger starter setup, in battery, cables or connections.

 

[mstone1968]

Re: Spark Plugs for 1974 50hp Evinrude #50473

Hello ezeke,
Thank You Very Much for the information. I have been looking everywhere to find the correct spark plugs for this engine. Thank You!!

 

[1975Ranger]

Re: Spark Plugs for 1974 50hp Evinrude #50473

Long time ago...but I just went thru the same problem. I found the right plugs -GAPLESS- from WEST MARINE.
Keith

 

[aaronmcc79]

Re: Spark Plugs for 1974 50hp Evinrude #50473

The Clymer repair manual says Champion plug type UL77V non adjustable gap.