Spark testing

[Swell]

I've been testing the spark on my 1968 6hp Seahorse using a homemade spark tester which tests the spark from both cylinders at the same time. The gap is 1/4" for each and I get an intermittent spark for both cylinders. The harder I pull the starter, the better the spark, but it is still intermittent. If I test using a spark plug instead, there's a good consistent spark on each pull every time - not intermittent at all.

Is the 1/4" gap test supposed to produce a spark as consistently as you would expect to see on a spark plug? Or is it more of a case of - if it jumps the gap at all that's good, whether consistent or not?

 

[kbait]

Re: Spark testing

The recoil starters on those motors are low geared and don't spin the flywheel very fast for a good test.. I'd wrap a rope around the flywheel and give it a good pull and see how the spark looks. Should jump 1/4" and be blue and snappy. It needs to jump 1/4" air gap for test to be assured of sparking .030" plug gap under compression..

 

[Swell]

Re: Spark testing

The recoil starters on those motors are low geared and don't spin the flywheel very fast for a good test.. I'd wrap a rope around the flywheel and give it a good pull and see how the spark looks. Should jump 1/4" and be blue and snappy. It needs to jump 1/4" air gap for test to be assured of sparking .030" plug gap under compression..

Thanks, I'll try that. Should I expect the spark to be at the same level / frequency across a 1/4" gap as it would be on a spark plug held against the powerhead? I presume that the faster the spin the stronger the spark?