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165 L6 ignition coil problem

H

holinwtr

Regular Contributor
I had the boat out on Monday and after about 2 hours of running perfectly it just shut off while we were running. I touched the coil and it about burned me. So I figure the coil went bad. I installed a Mallory electronic ignition about a month ago and have run the boat twice, counting Monday. I called Mallory on Tuesday and they recommend using their coil that puts out 1.4 ohms. They also said it has an internal resistor. I noticed in my manual that the wire going to the positive side of the coil is a resistance wire. Is it ok to have a coil with an internal resistor and a resistance wire? The reason I ask is because I can get a replacement coil from Napa that does not have an internal resistor. The one from Napa also puts out 1.4 ohms.
Thanks
 
The resistance wire reduces the voltage to the points to about 9V or so.Keeps from burning them out. The coil for this type of ign is non-resistor.
When electroninc ign came about, the ign wire now supplies a full 12V to the coil and the "internal-resistor coil " came about.Using a resistance wire and an internal resistance coil will drop the voltage too far for the coil to perform properly.
12 feed= internal resistor coil
resistance wire feed= non internal resistance coil.
 
So here is an update on the situation. I got a replacement coil from napa and one from Mallory. I wanted to have a back-up onboard in case I ever got stranded again. So the coil from mallory came and its supposed to have an internal resistor. In the directions it said not to remove the factory resistance wire and if there is no resistor that one needs to be installed. The one from Napa also requires an external resistor. So I also bought a ballast resistor from Napa. I put the new coil from Mallory on today and she fired right up and ran good. I checked voltage at the battery and had 14. I then checked it at the positive side of the coil and had 14. I know that at the coil you should have at least one volt drop. The coil started getting real hot too. So I put the ballast resistor in the wire going to positive side of the coil. Now I have 9 volts at the coil and everything is working fine and the coil doesnt get so hot. Question is: Is 9 volts at the coil ok?
 
thats what the ballast resistor is supposed to do.Perhaps the original wire or ballast resistor was removed at some point
supplying full 12v to the coil.
 
I have had the wiring harnesses on older point engines apart before.

There is a special wire ( it is not copper wire it is some different material) and it is about 3 feet long It measures about 2.2 ohms. It is tied into the purple wire(s) and taped all up in the harness. If that has been removed or replaced then your fix is the correct one!!!!

Did you measure the ohms of the EXTERNAL ballast resister? You should so you know//

Ohms law..........E (volts) = I (amps) X R (resistance) E=IR

therefore in a points iginition (14 volts/ 2.2 ohms = 6.4 amps)

if you remove the resistor ( 14 volts / (say .5 ohms {normal wire resistance or even less}) = 28 amps or more) this is why the coil got HOT!!

The resistor reduces the current to the coil.......

The question would be, why they just did not design a coil and ignition components that could handle the full load and not need a resistor at all............I never understood that one.........
 
Both coils I bought are rated at 1.4 ohms which is what the Mallory tech said I needed for my electronic ignition. I did not measure the ohms of the external ballast resistor because I don't know how. I don't know which setting the meter needs to be on or where to put the leeds. Do you measure ohms with the engine running or not?
Thanks
 
Its the Mallory E-spark electronic conversion. It's basically just the plate and a new rotor cap the sits in my old delco dist. I think with 9 volts going to the coil now it should be just fine.
 
Converting from points to a electronic conversion you still MUST maitain the stock voltage/current. So yes the 9 volts is correct and you should be all set.

The ohms you posted of the coil may or may not be of importance. The key here for our discussion was wether or not you had the correct ballast resistance.

Now you do!
 
I'm glad I got that figured out. I don't know how that coil lasted 4 years while getting the full 14 volts but it did. I wonder what will break and leave me stranded next time. LOL It's always something! Thanks again fellas
 
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