No spark, been reading...need ideas

[5thhorsemann]

You can also hold the end of the cable end in your fist and put your knuckles on a good ground. You will know FOR SURE if there is a spark. It doesn't hurt if you only fire the coil once.

[Patcon]

Zed Head

That is what I did coil wire in coil with the metal tip near a suitable ground; tap the negative lead to ground, no spark. I could see the circuit being made on one of the coil but no spark.

5th

I'll pass on that one. I have been bit by a coil once and am not interested again. Admittedly it was a GM hei and not a 240z coil...

I guess I could put a plug in the coil wire and put the strap to ground to make sure there is not too much gap.

Charles

[Patcon]

I have found the primary and secondary resistance readings for the MSD coil I have and the 240z coil I have. I need the resistance readings for the 280z, 280ZX and 280ZX turbo coil. I don't know what the third coil I have is from... I found the FSM's on Xenon but I didn't want to have to try to download and get them unzipped. If someone has that info close at hand, that would be great.

Thanks, Charles

[FastWoman]

I might be stating the obvious but if you have power through the coil posts (the primary circuit) and you're seeing a spark when you tap the negative to ground, you should see a discharge from the main center wire of the coil if it has a gap it can jump to ground.

... except the coil might have an internal short (e.g. from overheating and insulation breakdown). A spark on the primary merely means current flow.

[Zed Head]

True. I was just suggesting what should happen with a good one. Plus he's tried three coils so something is awry.

Patcon, are you sure that you're grounding the coil main wire to a good ground. Wouldn't hurt to confirm the path back to battery.

Just guessing.

[FastWoman]

Might also be a weak connection to the (+) terminal of the coil.

[Patcon]

Haven't tried straight to battery yet, but did use the voltmeter today.

MSD coil should have .7 Ohms on primary coil 4.5K ohms on secondary and ballast @ .8 Ohms

Tested out as .9 Ohms on primary coil 4.38K Ohms on secondary and 1.0 Ohms on ballast

240 coil 1.5 to 1.7 Ohms on primary 9.5-11.6K on secondary

tested as 1.6 Ohms on primary and 8.17k Ohms on secondary

Mystery coil (looks alot like a 240z coil; similar size and bracket)

tested as 3.6 on primary 7.58k on secondary

Are these all toast? I don't really want to buy a new dizzy or coil. If I need parts I will probably do the 280ZX dizzy upgrade to eliminate the points and the ballast resistor although it will be hardersince I don't currently have a functioning ignition system.

Thanks, Charles

[Patcon]

Bump

for test results

Are the coils dead or just weak? I really don't understand how significant or not these resistance readings are out of spec

Thanks, Charles

[Zed Head]

They don't look that bad.

I got curious and I have a spare coil and a spare 12 volt battery and a spare coil wire. It's a 1978 280Z coil.

1.1 ohms primary (barely over spec. of 1.02 for 1978)

10 ohms secondary (in spec.)

Connecting the positive side to batt. positive, and the negative side to the battery but with one end loose, and rigging the coil wire about .040" away from the negative terminal, tapping the negative wire to the coil negative gives a spark across the coil wire to battery negative. I found that it was easier to hear the spark than see it and that it worked best with a quick tap, not holding the negative on, then releasing it. Electricity is fast. If I held it on the the negative coil post for a second then took it off, I couldn't get a consistent spark. Maybe the coil can overcharge or saturate (?). I know a little bit but can't explain why that would be.

If I sat there and tapped the wire to the negative post quickly I could hear the coil primary zapping the negative battery post each time.

Anyway, with just a coil, some wires and a battery I could verify that I could create a spark. The coil is known to be good, I have used it before.

Hope that helps. Your resistance numbers look like one of those coils, at least. should produce some sparks.

[Patcon]

Zed Head,

I will try your setup in the next few days and see what I get on all the coils.

Thanks for the help

Charles

[Patcon]

Zed Head

When you tested straight off the battery was this a bench setup or in the car? It sounds like you grounded the coil wire back to the battery terminal also. Is that correct? Is there any problem with feeding the stepped up voltage back into the battery directly?

Thanks, Charles

[Zed Head]

It was a garage-floor setup. Feeding right back to the negative post. The voltage is high but the amps are low. Plus, in the car, that is actually what happens anyway. Even though the electrons have to travel through a mass of engine block and some wires to get there.

No problems, no worries, except that you should make sure the area around the battery top is open and ventilated. Out in the open on the garage should be fine, the spark will be no bigger than when connecting a battery cable with something on.

Batteries produce a small amount of hydrogen gas as a byproduct of use (never use a lighter for light to check your electrolyte level).