Bendix Scintilla coil numbers

[jpatti75]

Does anyone know if the Bendix Scintilla Coil 399-125 is the same/interchangeable with the Bendix Scintilla 399-756 coil?

JP

[20mercman]

One was considered the high performance coil. I will have to go look it up. I am trying to figure out this myself as I have measured these coils, one has ~ 3.5K ohms of secondary resistance and the other type has ~ 6.5K ohms on the secondary.

Steve

[mr-asa]

The higher resistance coil would probably indicate more turns, more turns will result in more voltage, I would bet that the higher resistance coil would be the high performance one.

Provided, of course, that there are no issues with corrosion or the connections or any of that fun stuff.

[20mercman]

Well, I just went and looked it up. The 399-756 is the older coil. It has the higher resistance on the coils I have measured, which threw me when I read this the first time. I had suspected as Mr. Asa has suggested that the higher resistance would have more turns…. From the Mercury manual. "The new, high-output coil 399-125 has a green plastic sleeve on the primary lead. The primary lead has but one wire on the coil, while the ground wire is composed of 2 wires. These leads both come out of the same end of the coil. The 399-756 coil primary lead has 2 wires, while the ground wire has but one. There are 2 types of this coil, one with both leads leading out of the one end, the other with one lead out of each of the ends. (The latter is the obsolete type.) " "The readings of the 399-125 coil are listed on the Test Data Chard, preceding. This coil has a different interior winding resulting in a much higher amperage or primary index reading. Some of the high output is derived from the new high output rotor (20599), a 2 pole rotor." When I go back and look at the Test Data Chart, it shows the same specs for both coils. 2.1 max amps, and a secondary Continuity of 50 max. I would surmise that these readings are off of the Merotronic tester, as they don’t seem to translate directly to my ohm meter readings.

Steve

[jpatti75]

Thanks much, guys.

Steve, I am working on a first-year production KE4 with the 399-756 coils according to the manual. Of course, the coils are toast (despite reportedly being a "runner"…no chance) and will need to be replaced. I haven’t worked on a Bendix in a few years (since my Mark 20 restoration), and for whatever reason, the coils just looked smaller than what I remembered the Bendix to be, which is actually what sparked my question. I have only seen the 399-125’s for sale, and I was worried I was going to have to hunt long and hard for the correct coil. Glad to hear that the 125’s will do the trick…when I decide to pry my wallet open and pay for them. 😮

Appreciate all the help!
JP

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