Ignition coil testing - I may be losing some knowledge here, so can I get confirmation here?

[moparedtn]

Coil in question is one of the old yellow "square" Accel coils....
Am I losing it or does it mean the coil is bad if there is no continuity between either of the primary leads and the big secondary
("coil wire") outlet?

 

[Mopars & Missiles]

Continuity only between the Neg & Pos terminals on the coil. The High voltage terminal (Coil wire) is completely isolated from the other two. No continuity.

 

[Mopars & Missiles]

A coil has two separate windings, the primary and the secondary. Both are completely isolated from the other one, with the exception of inductive coupling. The primary winding is the 12 volt winding powered by the battery. The secondary winding is your high voltage to your spark plugs. That circuit is completed thru the spark plug to ground at the cylinder head.

 

[RemCharger]

What's the resistance between the posts

 

[Mopars & Missiles]

What's the resistance between the posts

It will vary somewhat depending on the coil. But the primary winding will basically be a fairly low resistance.

 

[moparedtn]

It will vary somewhat depending on the coil. But the primary winding will basically be a fairly low resistance.

Thanks for all the help - I'm just looking for a quick way at a glance at a flea market or swap
meet to determine whether a given coil is worth horsetradin' over.

 

[Davefinan]

I don’t know of any way to tell if the coil is good
Just by looking at it . Bad is a different story.
I understand not wanting to walk around all day at a swap meet with a multi meter though , I haven’t done THAT done yet.

 

[RJRENTON]

A coil has two separate windings, the primary and the secondary. Both are completely isolated from the other one, with the exception of inductive coupling. The primary winding is the 12 volt winding powered by the battery. The secondary winding is your high voltage to your spark plugs. That circuit is completed thru the spark plug to ground at the cylinder head.

Not entirely true.....most, if not all, ignition coils are auto transformers with two (2) seperate but NOT isolated windings.....+ & - and negative and high voltage winding.

Simple construction
BOB RENTON

 

[j-c-c-62]

Coil in question is one of the old yellow "square" Accel coils....
Am I losing it or does it mean the coil is bad if there is no continuity between either of the primary leads and the big secondary
("coil wire") outlet?

Last week I bought a few new Accel twin coil packs for 95-97 4cly 2.0-2.5 Mopars for my V8 wasted sparked application. I contacted Holley the current owner/distributor of the brand to get some technical details on the coil packs.
They did reply, and said they have no idea what they are. LOL

 

[Mopars & Missiles]

Not entirely true.....most, if not all, ignition coils are auto transformers with two (2) seperate but NOT isolated windings.....+ & - and negative and high voltage winding.
View attachment 1671672Simple construction
BOB RENTON

Terminology Bob, the way I say it and the way you say it, we may use different words but mean the same thing. But of course as always, you are right. (Just my opinion of course).

 

[RJRENTON]

Terminology Bob, the way I say it and the way you say it, we may use different words but mean the same thing. But of course as always, you are right.

Do you know the difference between an AUTO-TRANSFORMER and an Isolated Winding Transformer with a true primary and secondary windings?......beside impedance (AC resistance) and core loss (magnetic) plus copper loss (I squared R). Just FYI......
BOB RENTON

 

[davek]

Terminology Bob, the way I say it and the way you say it, we may use different words but mean the same thing. But of course as always, you are right.

NOT

 

[RemCharger]

Coil in question is one of the old yellow "square" Accel coils....
Am I losing it or does it mean the coil is bad if there is no continuity between either of the primary leads and the big secondary
("coil wire") outlet?

What kind of meter, and on what setting are you testing with?

 

[moparedtn]

What kind of meter, and on what setting are you testing with?

Sperry. Ohms.

 

[Davefinan]

Not entirely true.....most, if not all, ignition coils are auto transformers with two (2) seperate but NOT isolated windings.....+ & - and negative and high voltage winding.
View attachment 1671672Simple construction
BOB RENTON

This man does know what he is talking about

Whenever I have tested a good coil , I’ve gotten in the neighborhood of one and half ohms on the primary side and 9 kilo ohms from positive and negative to the secondary.

I believe Sometimes advice comes off sounding like criticism but either way , you can still learn something

 

[Davefinan]

I probably should have said “ stock type coil”

 

[RemCharger]

Fluke. Ohms.

 

[moparedtn]

View attachment 1672214View attachment 1672215

Ut oh...

 

[RJRENTON]

Ut oh...
View attachment 1672415View attachment 1672416
View attachment 1672417

The ohms function is for DIODE testing. It's best suited for a clamp on ammeter or voltage testing both ac and dc. I don't think it has the capability of testing high value ohms like the coil's secondary. A better DMM is a FLUKE # 117 with total auto ranging of resistance, voltage and current plus diode testing.

Typical Accel coil's have a very low resistance primary and a high secondary resistance...above 10k ohms to produce the high secondary voltage (volts to turn ratio between the primary and secondary). Perhaps you should consider a different digital meter???? Just my opinion of course.....
BOB RENTON

 

[moparedtn]

The ohms function is for DIODE testing. It's best suited for a clamp on ammeter or voltage testing both ac and dc. I don't think it has the capability of testing high value ohms like the coil's secondary. A better DMM is a FLUKE # 117 with total auto ranging of resistance, voltage and current plus diode testing.

Typical Accel coil's have a very low resistance primary and a high secondary resistance...above 10k ohms to produce the high secondary voltage (volts to turn ratio between the primary and secondary). Perhaps you should consider a different digital meter???? Just my opinion of course.....
BOB RENTON

I suppose I could just slap it on the car and see if it works....