Looks like you get to choose from these (depending on the year) Look at this chart & lots of great info here: http://www.maxrules.com/OMCplugchart.html
The 1977 model, 70 hp Evinrude outboard requires an NGK BZ7HS-10, or a Champion QL77JC4 Plug gapped to .030 in.
I use the QL77JC4 Champion plugs with a 0.030in gap.
70hp. what premix ratio do you use?
Evinrude and Johnson outboards decipher the year model of the engine, by use of the engine model number.
If it is a 2 cycle where you mix the oil with the gasoline then use 2 cycle marine oil. If it is a 4 cycle then use the weight recommended by Evinrude.
i got a 75 hp evinrude with a 6.6 gallon fuel tank it use 16 onces of oil
1959 thru 1963 Johnson and Evinrude use a 24 to 1 ratio. 1964 and up is 50 to 1
The 1990 model, 90 hp Evinrude outboard can use either an NGK BR7HS, or Champion L77JC4.
Four stroke
I have the same motor and use 50:1.
A 1979 70 HP Johnson burns about 3.5 GPH at 3/4ths WOT
50:1 on slow use and 40:1 on every day use