1991 Johnson/Evinrude EI 60 thru 70 outboards Service Manual, Page 141Get this manual
Pyrometer Procedure
1Install correct test propeller and place engine in test tank
"" Twist and remove spark plug leads before changing propellers to avoid accidental starting of engine
2Start engine and run at 3000 RPM for at least five minutesminutesAt 900 RPM, digital pyrometer should indicate 1400 150 (600 70 C) when held on the cylinder head r:;] 3Reduce engine speed and run engine at 900 RPM for five