Home-made spark tester w/video

[Craig-]

Made this spark tester out of an old ford v8 distributor cap. Replaced center electrode with bolt and end from tin can that was turned into a good circle on the drill press. There is a ground lead on center bolt with clip for grounding.
Slowing the video way down in media player, I can count the sparks in order. They are not right. Think it's time for a new power pack and coils maybe. PM me for one.

 

[Lion hunter]

Re: Home-made spark tester w/video

Maybe it can't happen because the center disk is grounded but is there any danger of backfeeding spark through the wires if the ground is not right and damaging something? Meaning that as 1 sparks it jumps the disk to 2 if the ground happened not hooked up good. And if not damage could you have spark traveling in opposite directions and interupt the process?

 

[Craig-]

Re: Home-made spark tester w/video

No more danger than a multiple tester to a common bar ground. If you don't ground it, it won't spark. If you don't ground your your ignition coil output you can do damage to the coils and power pack. So be sure to ground.

My other thought after playing back the video in slow motion is that the camera frame rate may not be recording as fast as the ignition fires, giving me a false count. At 700rpm the frame rate would have to be 50fps to be on the safe side to record every spark. I'm not sure the camera I used records that fast. I will check. Playing the video in super slow motion show some really erratic sparks.

EDIT: Only records 30fps which would work at 450rpm. I don't know what RPM the starter cranks it over at, probably slower than 450, depending on the battery charge. Typical playback rate for a TV is 30fps also. So I think the test is good from my original recording anyway. As long as the start circuitry of the power pack is the same as the run, I don't think there's a difference.

 

[jonesg]

Re: Home-made spark tester w/video

I like the idea, now to steal a distributor cap....

 

[roncoop75]

Re: Home-made spark tester w/video

No more danger than a multiple tester to a common bar ground. If you don't ground it, it won't spark. If you don't ground your your ignition coil output you can do damage to the coils and power pack. So be sure to ground.

My other thought after playing back the video in slow motion is that the camera frame rate may not be recording as fast as the ignition fires, giving me a false count. At 700rpm the frame rate would have to be 50fps to be on the safe side to record every spark. I'm not sure the camera I used records that fast. I will check. Playing the video in super slow motion show some really erratic sparks.

EDIT: Only records 30fps which would work at 450rpm. I don't know what RPM the starter cranks it over at, probably slower than 450, depending on the battery charge. Typical playback rate for a TV is 30fps also. So I think the test is good from my original recording anyway. As long as the start circuitry of the power pack is the same as the run, I don't think there's a difference.

450 rpm is 7.5 rps (rev/sec). If I were building a triggering circuit to snap the camera and wanted a decent sampling rate I'd try to get closer to 10X the frequency or 75 fps. Half that is pushing it. Your going to miss events at that rate fairly regularly.

Edit: After pondering this in the shower, you actually have 4 events per rev, or 30 events per second. Sampling rate way to low. I'm surprised the video looks that good.

 

[Cofe]

Re: Home-made spark tester w/video

Cool Idea!

I'm gona make one. Should I use 7/16 gap from tin can lid to the post? Or should I make a couple different sizes of tin can lids?

Who Took My CAP?

 

[Rick.]

Re: Home-made spark tester w/video

Better get a cap soon before they are all gone. Really a neat idea and I can't see a problem with it as long as it's grounded. And, it's fun to watch as well. I think you did good. Rick.

 

[Craig-]

Re: Home-made spark tester w/video

Cool Idea!

I'm gona make one. Should I use 7/16 gap from tin can lid to the post? Or should I make a couple different sizes of tin can lids?

Who Took My CAP?

Thicker material would be better, the one in video is 7/16" gap. The tin can lid distorts when bolting it down. Holesaw in 1/8" aluminum would work great. Tweak the diameter with the center bolt chucked in a drill-press as a lathe.

 

[Craig-]

Re: Home-made spark tester w/video

450 rpm is 7.5 rps (rev/sec). If I were building a triggering circuit to snap the camera and wanted a decent sampling rate I'd try to get closer to 10X the frequency or 75 fps. Half that is pushing it. Your going to miss events at that rate fairly regularly.

Edit: After pondering this in the shower, you actually have 4 events per rev, or 30 events per second. Sampling rate way to low. I'm surprised the video looks that good.

30fps x 60 = 1800fpm divided by cylinder count (4) = (450)rpm
Cranking with starter = ?rpm

 

[Craig-]

Re: Home-made spark tester w/video

For those interested I did a frame by frame count of spark order. Should be 12341234?etc. *indicates miss fire. The video posted is the following.

123**341*412*123*234**412*123*234**412*123**341*412*123**341*412*123**341*412*123**341*412*123**341*412*134*341*412**234*341*4123*234*341**123*234**412*123*234**412*123**341*412*123**341*412*123**341*412**134**412*123**341*412**234

Everything else pointed to a fuel problem except for wet plugs, likely clogged high speed jets but it is an ignition problem, hard to tell that at normal playback.

1 sparked 46 times, 2-34, 3-37, 4-39 and 71 miss fires, no wonder plugs were wet. Motor starts fine, planes out quick, but is missing 1500rpm at WOT.

 

[Cofe]

Re: Home-made spark tester w/video

Is a person in danger of being hypnotized from watching this thing fire?
All that is repeating through my brain after that last post is "musical chairs"

 

[Happy_Jack]

Re: Home-made spark tester w/video

Way cool, and you could use an 8cyl cap for any engine configuration around.

Can't wait to open my next can of beans...then wait until my brother goes to sleep, and get his distributor cap out of his truck.....

Thanks for a great idea.

 

[Craig-]

Re: Home-made spark tester w/video

Way cool, and you could use an 8cyl cap for any engine configuration around.

Can't wait to open my next can of beans...then wait until my brother goes to sleep, and get his distributor cap out of his truck.....

Thanks for a great idea.

Sure thing. It's even more fun watching in slo-mo.

Ordered the new parts today, so hopefully by the weekend I'll have the sure results. Also talked to the tech guys at CDI, they said ignition modules are flying off the shelves this year due to hotter than usual temperatures.

PM me for one.

 

[Craig-]

Re: Home-made spark tester w/video

I figured out the cranking speed is higher than 450rpm, and the frame rate on the camera didn't record all the sparks. So the number of misfires has to be off somewhat. Trying to borrow a higher speed camera to try it again, also will arrange wires so they fire in a circular order which will be easier to detect misfires. Will post the new video when done.