octain 87 or 89

[48tony]

Hi guyies, I would like to get some feedback on what octain I should be useing on my 1970 60 hp johnson.My book says to run atleast a 87 octain or higher but that was 40 years ago. With todays gas being junk should I run the 89 or stick with the 87 50-1 and add sea foam in each tank? I have glm after market pistons that I put in when I rebuilt this motor.These pistons are a lower comprestion ratio to run better with the new gas of today.Butt I have seen this qustion asked and everyone says something different.What is safely recommended.Allso I found out I was running the incorrect spark plug in the motor.I had champion l77jc4. When I went to buy new ones the guy said I should be running the ql77jc4.He explained to me it was a hotter plug.I gapped them a little over 30 as I plan to do a lot of trolling this spring.Can I get some feedback on all this Thank you Tony

 

[joereeves]

The difference between a Champion L77JC4 and a QL77JC4 plug is that the "Q" is a suppresor plug designed to quiet ignition noise etc that might interfere with electronic/electrical equipment. Both plugs have the same heat range of "77".

That engine is not designed for constant trolling but if that's what you're going to be doing, try the original spark plug gap of .040 and the newer recommended gap of .030. One or the other may give you improved low rpm performance.


Your engine will run fine on the 87 octane.

 

[48tony]

joe,Thanks for the fast reply and the key info I needed Tony.