what is correct gap for spark tester on Johnson 18hp 1964?

[oldfarmall]

Hello-

Can anyone tell me correct gap for using a spark tester on a 1964 Johnson 18hp motor? I have seen anywhere from 1/4" to 7/16" with bright blue lightning bolt. My Johnson service manual says 1/8", majority of threads I have seen say 1/4", but some say 7/16"? I am confused, 7/16" seems excesive. Want to get my motor running right. Thanks in advance.


Jesse

 

[wg]

Re: what is correct gap for spark tester on Johnson 18hp 1964?

Spark should jump 5/16"

 

[kbait]

Re: what is correct gap for spark tester on Johnson 18hp 1964?

I check for 1/4" on points motors, 5/16" on CD ignition models. Blue snappy bolt. If yellow or intermittent, dig in.