Testing Mallory Coils

Hey guys how do you test the old Mallory coils and what #'s are you looking for to know that its good. Its a Mallory 28900 A Thanks in advance!

 

With an ohm meter and I have the numbers, I'll try to post them tonight.

 

ohms

With an ohm meter, one lead on one of the top terminals, and the other on the coil wire terminal, you should get about 14.5 ohms when new. This value may drop a bit after some use, down to maybe 14.2. If you have a coil that is under 14 ohms, or over about 14.8, I wouldn't use it any more.

 

Whats happening when they are gaining ohms, mine are higher than the ratings?

 

Hi guys, there are 2 readings that are important. The first is taken from the ground terminal to the primary positive terminal, this will be a low reading (I would have thought less than 14 ohms but that may be right). The second reading is taken from the ground terminal to the HT coil output terminal and this shiould be much higher (many hundreds of ohms). The difference in the two provides the step up voltage conversion from the primary voltage of tens to hundreds of volts to the secondary which is typically 30,000 or more. SoDak, please advise what your readings are. Cheers

 

I would have to recheck them. We have 5 of them. I had some issues this season and it ended up being a toggle switch, but in an effort to find the issue I was ohming coils. I remember talking with Zig that all my readings were high (probably my ohm meter). They can't be too bad, we won the championship

 

fair comment !! fyi, it is unusual for a coil to go high resistance, they will normally go open circuit (ie: dead) or can suffer from 'shortened turns' which can sometimes show as a reduced resistance. In that case you need a proper test unit to confirm the condition of the coil. Happy racing

 

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