Over the years with my T when I have to check spark at the plugs, you simply have a screw driver and hold it by the plug and you see spark. Nice snappy spark is good, weak spark jump is bad. Really simple. If you have a starter car and its not working you crank it over until you see spark or have someone hold it to see if your getting spark when using the starter. I am positing this question here because someone has to have a creative solution.
Here is the issue, I have a Non-Model T ( '14) Cadillac which has a standard distributer set-up. It has an electrical gremlin or so I think. Starts great cold, but when warm, not so good. I suspect spark is weak due to a compromised rotor or a suspect ground somewhere.
I would like to know if someone has a way to check the spark at each plug, measure it to check that it is strong from the steering wheel position, My daughter / screw driver holder went to college and isn't home this summer so I don't have a willing screw driver holder. I Was thinking hooking up a meter to all 4 plugs or some kind if indicator light set-up that I could temporarily mount at the dash. HAs anyone come up with a solution for this with a T?
Getting Spark at the Plugs / Lost my Screw Driver Holder
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John.Zibell
- Posts: 361
- Joined: Mon Jan 07, 2019 9:09 am
- First Name: John
- Last Name: Zibell
- * REQUIRED* Type and Year of Model Ts owned: 1926 Tudor
- Location: Huntsville, AL
Re: Getting Spark at the Plugs / Lost my Screw Driver Holder
If you have a single coil, that is probably the culprit. Works when cold, fails when hot.
1926 Tudor
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Art M
- Posts: 964
- Joined: Wed Jun 19, 2019 12:57 pm
- First Name: Art
- Last Name: Mirtes
- * REQUIRED* Type and Year of Model Ts owned: 1923 Touring
- Location: Huron, Ohio
- Board Member Since: 2016
Re: Getting Spark at the Plugs / Lost my Screw Driver Holder
I could be the capacitor or the coil. I doubt it is the distributor rotor or cap. No need to check spark at each spark plug.
Art Mirtes
Art Mirtes
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Mark Gregush
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- First Name: Mark
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- * REQUIRED* Type and Year of Model Ts owned: 1925 cutdown PU, 1948 F2 Ford flat head 6 pickup 3 speed
- Location: Portland Or
- Board Member Since: 1999
Re: Getting Spark at the Plugs / Lost my Screw Driver Holder
Close friend of mine (RIP) had an induction setup hanging from the radiator support bar with 4 bulbs. When the switch was flipped, each bulb would light up as the plug fired. Might not show intensity of spark, it would show any misfire or missing spark. Not sure how to describe it to be able to look it up and post a link, maybe someone else can.
The other option might be to check the spark from the coil while hand cranking both cold and hot. You really don't have to check at each plug. Checking each plug would be telling you that that terminal/wire/plug is in order not what kind of spark the coil is putting out.
The other option might be to check the spark from the coil while hand cranking both cold and hot. You really don't have to check at each plug. Checking each plug would be telling you that that terminal/wire/plug is in order not what kind of spark the coil is putting out.
I know the voices aren't real but damn they have some good ideas! 
1925 Cut down pickup
1948 Ford F2 pickup
1925 Cut down pickup
1948 Ford F2 pickup
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nicklm
- Posts: 65
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- First Name: Nick
- Last Name: Miller
- * REQUIRED* Type and Year of Model Ts owned: 1926 touring
- Location: NRedington Bch, FL
Re: Getting Spark at the Plugs / Lost my Screw Driver Holder
I agree with art m. I had a Model A for many years and the condenser would be the most likely problem with heating up and failing. The single coil would be next, I think.
Nick
Nick
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John Codman
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Re: Getting Spark at the Plugs / Lost my Screw Driver Holder
Many - many years ago I bought an inline spark tester. One end plugs in to the spark plug just as a plug wire would, the other end is plugged into the spark plug wire. It doesn't affect the voltage to the spark plug, and flashes when it gets the high-tension voltage from the plug wire. The only thing it won't tell you is whether the plug is dead shorted.
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Mark Gregush
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- Location: Portland Or
- Board Member Since: 1999
Re: Getting Spark at the Plugs / Lost my Screw Driver Holder
You can still buy them, check Snyders catalog. They can also show if the polarity of the coil hook up is correct.John Codman wrote: ↑Mon Jul 17, 2023 11:38 amMany - many years ago I bought an inline spark tester. One end plugs in to the spark plug just as a plug wire would, the other end is plugged into the spark plug wire. It doesn't affect the voltage to the spark plug, and flashes when it gets the high-tension voltage from the plug wire. The only thing it won't tell you is whether the plug is dead shorted.
I know the voices aren't real but damn they have some good ideas!
1925 Cut down pickup
1948 Ford F2 pickup
1925 Cut down pickup
1948 Ford F2 pickup
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nsbrassnut
- Posts: 148
- Joined: Sun Jan 06, 2019 5:30 pm
- First Name: Jeff
- Last Name: Lee
- Location: Nova Scotia
Re: Getting Spark at the Plugs / Lost my Screw Driver Holder
Perhaps a long shot, but I have seen this problem.
All plugs spark good at full retard. But one or more may quit when the timer is advanced. It may be possible that one of the timer connections could come too close to some other metal items when advanced that suddenly grounds it out. But usually only one plug will act up at a time this way at a time.
Potential causes, fan belt rubbing on the timer or wires (new belt used?) when the timer is advanced. Spark rod or its cotter pin getting too close to a terminal. Stuff like that. Hard to spot even with a light down there.
Another long shot. Failing wires in the wire harness that may work in one position then not when flexed to another position. I had that happen to a none Ford in the point wire inside the distributor. Worked fine with normal vacuum, climb a hill and when the auto vacuum retard moved the point plate the engine would miss fire. Took months to trace it to broken wire strands inside the insulation where it wasn't obvious until tested with an ohm meter and then flexing the wire.
Good luck with the hunt.
Jeff
All plugs spark good at full retard. But one or more may quit when the timer is advanced. It may be possible that one of the timer connections could come too close to some other metal items when advanced that suddenly grounds it out. But usually only one plug will act up at a time this way at a time.
Potential causes, fan belt rubbing on the timer or wires (new belt used?) when the timer is advanced. Spark rod or its cotter pin getting too close to a terminal. Stuff like that. Hard to spot even with a light down there.
Another long shot. Failing wires in the wire harness that may work in one position then not when flexed to another position. I had that happen to a none Ford in the point wire inside the distributor. Worked fine with normal vacuum, climb a hill and when the auto vacuum retard moved the point plate the engine would miss fire. Took months to trace it to broken wire strands inside the insulation where it wasn't obvious until tested with an ohm meter and then flexing the wire.
Good luck with the hunt.
Jeff