QD19 spark.. It’s alive I tell you, ALIVE!

[Steve A W]

Roll it over with the lights off and watch for sparks.

Steve A W

Member of the MOB chapter.
I live in Northwest Indiana

[legendre]

quote Steve A W:

Roll it over with the lights off and watch for sparks

Empiricism at its finest!

[Mumbles]

Just because the plug wires check out OK with an ohmmeter doesn’t necessarily mean they can carry the current needed to fire the plugs.

For example, a ’59 Fastwin I have nearly drove me over the edge trying to figure out why it would start missing and drop a cylinder while I was always at the far end of the lake. Everything under the flywheel was brand new OMC/BRP parts except for the plug wires which came off the end of a roll which was more than a few years old. After hauling the boat home and going thru the ignition system several more times, out of sheer desperation I changed the plug wires with fresh, new wire and BINGO! Here we go now! Full power and reliability the way it is supposed to be! Mumbles was a happy camper that day as he didn’t have to break out the vodka and Valium. Together.

Retracing my steps, I remembered the first replacement wire cracking a bit as I unwound it from it’s roll. It was the last few turns on the roll and I figure the cracking I heard was the strands inside breaking from being straightened after being tightly rolled up for so long. There could have been one unbroken strand left inside giving enough conductivity to give a good ohm reading but not enough conductivity to let the needed current flow to fire the plug.

There’s no moral to this story but spark plug wire can be just like some people are, nice on the outside but rotten to the core. 😀

[Mumbles]

quote legendre:

quote Steve A W:

Roll it over with the lights off and watch for sparks

Empiricism at its finest!

Common sense to the masses.

https://www.youtube.com/watch?v=4VD_0xOBLFw

[legendre]

quote Mumbles:

Retracing my steps, I remembered the first replacement wire cracking a bit as I unwound it from it’s roll. It was the last few turns on the roll and I figure the cracking I heard was the strands inside breaking from being straightened after being tightly rolled up for so long.

Did you ultimately verify if that was the case – that is, broken core strands? That would have to be a pretty dang old reel of wire, for the inner conductors to break as it was unwound. Now, if there was a lot of corrosion going on inside, that’s one thing – but absent that, copper doesn’t normally embrittle just sitting still in a reel of wire.

If anything, I’d think the ‘cracking’ you heard was one or more insulation layers, as plastic & rubber are much more likely to perish just sitting around for years on a shelf.

Oh.. and not to get too pithy, but if sense were common, we’d all have it! 😉

[Mumbles]

quote legendre:

Did you ultimately verify if that was the case – that is, broken core strands?

I didn’t have to verify broken strands. I KNEW they were broken.

If you re-read my post, you will notice fresh, new replacement wire solved the ignition problem. That’s enough verification for me.

[beerman57]

I don’t get it, thought I found it when I noticed the electrode on #2 was shorter than #1, switched coils – no change. So I switch the points, figure I’ll need a set of points if #2 has spark and #1 doesn’t, or if everything stays the same, it will mean plug wire. Wouldn’t you know it, spark on both, started RIGHT UP, purred real nice. Set low speed at 1.5 turns / high at .75 turns. For running on a hose it couldn’t have been any better, idled right down, never sneezed once. Now I finally get to break in this rebuild.
Thanks for all the input, for all the ignition problems I deal with on my motors and friends’ motors, you would think I would be an expert!

[Author]

Posts