Ballast resistor getting too hot to touch

Jadog

Cadet
Joined
Sep 7, 2021
Messages
7
My setup calls for two ballast resistor. Can I use only one?
I have a 3l mercrusier 140hp
Mallory 6001m distributor calls for a 1.4 ohm
What ballast resistor does the coil need?
I attached details to my coil
I have a spare .8 ohm resistor but not sure if I can use it or not.
 

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achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
My setup calls for two ballast resistor.
No it does not. You are reading the tag incorrectly.
It's calling out that you need an external resistor, then it's indicating the primary resistance OF THE COIL, 1.55 ohms (or is it 0.45ohms? I have no idea. You'll need to put a ballast resistor of a known value in and see what voltage you have on the coil + to determine a) the actual primary resistance and b) if the ballast is the right one.) That 'Secondary resistance' is also OF THE COIL...
Can I use only one?
You normally only use one.
I have a 3l mercrusier 140hp
Merc started using the 3 litre engine in 1969, and are still using it. A year would be helpful. Or better yet, the engine serial number.
Mallory 6001m distributor calls for a 1.4 ohm
A 1.4 ohm what? (coil or ballast resistor?)
What ballast resistor does the coil need?
Depends on the coil's primary resistance.
I attached details to my coil
Interesting. I suspect that same box is used to package multiple different coils, and the person at the shop forgot to stroke out the specs that don't apply to the coil in the box when you bought it.
I have a spare .8 ohm resistor but not sure if I can use it or not.
Put it in and measure the voltage at the coil+ with the points CLOSED! It should be around 7 or 8v. If it is, you have the 1.55ohm coil, and you're on a winner. If it's around 5 or 6v, then the coil primary is 0.45ohms, and you'll need a smaller value ballast (like around 0.25ohms) or a coil with 1.55ohm primary resistance. If you measure 12v, the points aren't closed. If you measure 0v, you're on the coil-, not the coil+.

Chris......
 
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Jadog

Cadet
Joined
Sep 7, 2021
Messages
7
No it does not. You are reading the tag incorrectly.
I appreciate your help and sorry for the lack of info. I think you misinterpreted me and I wasn’t clear. The coil needs a ballast resistor as well as the distributor (Mallory 6001m) as the manuals says. Would using one work?
The engine is a 1986.
A 1.4 ohm what? (coil or ballast resistor?)
The manuals stated that 1.4 ballast resistor for that distributor.
I’m pretty sure the coil is 1.5 ohm.
I’m currently using a 1.4ohm ballast resistor for both positive wires to coil and to distributor.
Here a link to the coil https://www.amazon.com/dp/B08D99RZD...abc_39MYWNHF662HJQX2CZ7Y?_encoding=UTF8&psc=1
 

bruceb58

Supreme Mariner
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Mar 5, 2006
Messages
30,614
You need a ballast resistor to the coil. That's the only place you need one.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
I just downloaded the instructions for the 6100M. It does not say to have 2 ballast resistors, it says you need a ballast resistor OR a loom resistor, not both... You're 0.8 ohm resistor is not suitable. If your engine originally had a points system, once I get home I'll check the spec on your resistive wire. Give me a couple of hours.

BTW. That 1.5 ohms is the coil's internal resistance, not a required resistor for it....

Chris...
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
IF your engine had points originally, and the resistance wire is still in place, it has a resistance of 1.8-2.0Ω.

Chris...

Found this online. How to wire up your distributor... (note, only ONE ballast resistor. If you have a resistance wire, it's the same deal)

1632274820983.png
 
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