Reply To: Spark tester.

[chris-p]

kerry wrote:

If you want to go “old school”, get a new spark plug, hose clamp, and a wire lead with an alligator clamp. Hose clamp the wire to the threads of the plug. Attach plug wire to plug, clip lead to a good ground on the motor, crank away. Worked for Grandpa, Dad, me, and my son. Yes, I have a Harbor Freight tester, but I can’t always see it in the light. I can hear a good spark “snap” with the homemade tester.

Kerry, just one thing to add to this to potential new people reading that may not know. Ill assume you open your plug gap up to 1/4″ not 020, but new members reading this may not know that.

For new members, it is a lot harder for a plug to fire under compression in the cylinder then it is out of the plug hole in open air. That is why it must jump a 1/4″ gap in open air, to say that the ignition is sufficient. Simply jumping an 020 gap in open air, does not necessarily mean it will fire under compression, and does not necessarily mean your ignition is functioning as it should. You may be chasing your tail for days trying to figure out what is wrong!

I have had more than a handful of guys bring their motor to me to look at. They said they had good spark since the plug would spark when holding it up to the block. When I put my inline tester on it at 1/4″ gap, no fire. Weak ignition.

I fell for that myself in the past since I read it on the old internet! Someone on here set me straight, and Ill never forget it now.