Coil Test???

[HammerDown]

Anyway to ohm out a coil on the bench to tell if it's good...I belive there is but I can't recall.
One of those MSD due-hickys.

[Infomaniac]

I think the MSD site has the specs.
Generally the primary windings + to - small posts will measure single digits ohms.
The secondary windings small post to coil wire terminal will measure a few thousand ohms.
An open will probably be the most common defect.

[396_WAYS_TO_SPIT]

Since I work at autozone and yes we can test them, I have that info available for you;)
Primary 1.2-2.0 ohms
Secondary 6.3-11.7 ohms
396

[396_WAYS_TO_SPIT]

Originally posted by Infomaniac
I think the MSD site has the specs.
Generally the primary windings + to - small posts will measure single digits ohms.
The secondary windings small post to coil wire terminal will measure a few thousand ohms.
An open will probably be the most common defect.
Right on the money;)
Thats why he calls himself infomaniac ;) ;)
396

[Oldsquirt]

Originally posted by 396_WAYS_TO_SPIT
Primary 1.2-2.0 ohms
Secondary 6.3-11.7 ohms
A small correction that does make a big difference...
The secondary resistance should be : 6.3-11.7K ohms
:)

[396_WAYS_TO_SPIT]

Originally posted by OLDSQUIRT
A small correction that does make a big difference...
The secondary resistance should be : 6.3-11.7K ohms
:)
Sorry about that I was up lake:) old squirt is right;)
396

[HammerDown]

Thanks for the feedback. Now to gig out the trusty Blue Point.

[HammerDown]

2 Coils, one MSD Blaster 2 that I just brought inside to test.
And a chrome High Performance coil that was good when I took it off years ago for the MSD.
1). Chrome coil... + to - meter set @ 200 Reading> 01.7
MSD coil + to - meter set @ 200 reading>01.0
2). Chrome coil, meter @200(k) +or- to center tower reading> 13.2
MSD coil, meter set @ 200(k) +to- to center tower reading>04.7
What do ya think?
This is used on a Mallory dual point system with a resistor.

[396_WAYS_TO_SPIT]

Originally posted by HammerDown
2 Coils, one MSD Blaster 2 that I just brought inside to test.
And a chrome High Performance coil that was good when I took it off years ago for the MSD.
1). Chrome coil... + to - meter set @ 200 Reading> 01.7
MSD coil + to - meter set @ 200 reading>01.0
2). Chrome coil, meter @200(k) +or- to center tower reading> 13.2
MSD coil, meter set @ 200(k) +to- to center tower reading>04.7
What do ya think?
This is used on a Mallory dual point system with a resistor.
Run the msd and ditch the so called "high performance" coil;)
chrome one is junk, and the msd is still lookin' good;)
396

[Oldsquirt]

Damn, wish I had checked this earlier. Had my boat here at home and I've got the Blaster 2 on it. Could have checked it to compare numbers.
Personally, that Secondary resistance down in the 4.7K range on the MSD is a bit suspect. Would like to know what MSD specifies, but couldn't find any numbers on their website.
Hammer, I'll run by my storage and check my coil for you tomorrow.:)

[Wet Dream]

If you don't have the tools there is a less scientific method:
Have someone crank over the engine while placing your thumb over the coil wire to the disributor. Get a good "reading" from that. Then replace the coil and compare the two. You'll know the difference. ;)

[HammerDown]

For the Blaster 2
Primary Resistance 0.7 ohms
Secondary Resistance 4.7 k
:idea2: Hmmmm

[promod]

hey hammer while peeing on the coil spine the motor over kinda like peeing on electric fence just kidding :D

[Oldsquirt]

Originally posted by HammerDown
For the Blaster 2
Primary Resistance 0.7 ohms
Secondary Resistance 4.7 k
:idea2: Hmmmm
You know, I looked all through the tech/troubleshooting sections for that info. I guess I should have checked product info as well.:D
Even though the primary resistance you measured is higher than the spec, there is always some room for variation. I'll bet that coil is fine, but I will still check mine for comparison.

[OkieDave]

Does it make sense that a coil works ok when its cold and stops working when it heats up? how can you test for that?

[Oldsquirt]

Okiedave, yes, it does make sense. If there is a break in the coil windings that makes contact when cold, when hot it can pull the contact open. Same applies with a short between the primary and secondary windings. If you can catch it in the act and quickly perform a resistance test, you could confirm the problem. Would probably be simpler to just replace a "suspect" coil.

[Oldsquirt]

Hammerdown, got the results from my Blaster 2 coil.
Primary resistance = 0.9ohms
Secondary resistance = 4.7K ohms.
Since mine was running yesterday, I know its OK.

[HammerDown]

Thanks again for the feedback. I'm thinking ambient air temp will give a slightly different coil reading.
With new points installed in the dual point Mallory and dialed in the way their supposed to the boat once again ran very strong, didn't miss a beat with the MSD Coil. So I guess the dwell being off caused the sputter and not the suspect coil.
1'st time in 7 seasons that distributor acted up, but i know I failed to check the Dwell in the begining of this season and lube the point blocks (my fault) :rolleyes:

[Wet Dream]

Originally posted by promod
hey hammer while peeing on the coil spine the motor over kinda like peeing on electric fence just kidding :D
Hammer must be in "Serious" mode. He's not answering to the light hearted posts. ;)

[tbanzer]

First thing I would do is lose the duel point and replace it with either a new electronic or an electronic conversion.

[Havasu Hangin']

Originally posted by okiedave
Does it make sense that a coil works ok when its cold and stops working when it heats up? how can you test for that?
Make sure you are using an external resistor if the coil doesn't have an internal one.