I have tested coils in the past by checking resistance and have not found it to be reliable. Ford shop books have a resistance test in them, but, if your problem is shutting down when coil is hot, for example, a cold test won't show a problem.
Edited by - 289kford on 04/24/2008 14:30:44
I've cleaned up my original coil that I found in the garage, the top does look pretty good for its age!! the yellow looks like it is a composite material that was dyed that yellow and not painted.
Should I may be clear coat it?? gloss or semi gloss on the black area??
I have found a second original yellow top coil in my garage!! 1 has 4/D and 1 has 2/B how do I tell the date code by this?? Thanks!
The date codes were ink stamped on the coil metal body and typically do not survive except on very low mileage cars.
If these are the numbers from the yellow top between the two wire posts - the common idea is that these are mold markings not datecodes.
Edited by - RalphJr on 04/28/2008 08:12:47
I went ahead and ordered a repro coil from VA Mustang, the guy assured me that they were from a good run, and they had not been getting any back, so between it and my 2 restored originals I should be set.
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I went ahead and ordered a repro coil from VA Mustang, <i>the guy assured me that they were from a good run</i>, and they had not been getting any back, so between it and my 2 restored originals I should be set.
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Hmm, guess that means there have been some "bad runs".
When the repro coils first came out, the internal wiring of the coil's terminals was backwards. The coil worked but overheated and eventually burned out.
Jim
Jim, I have an early repro coil myself. Would hooking it up backwards alleviate the overheating problem?
-Fred-
Fred,
The internal reverse hook-up was what a friend was told by a Ford dealer (the sponsor of our club) when the car (67 289 convertible) was diagnosed on a scope. A new Ford coil fixed the problem and they went back on the road to Santa Cruz. I think the bad coil came from NPD and they eventually replaced it saying they got a bad batch from their supplier. That's about all I remember. This happened when the repros first came out. As to reversing the leads, the theory says yes, my guts say no.
Jim
I just received my repro yellow top from VA Mustang, it "looks" pretty good when compaired to my 2 originals.
I also received 2 of their "DF-33" coil decals, in which the backing says "Official Licensed product" I have had a real time with my glasses clean and on making out the "FoMoCo" inside the oval...it sure looks to me like it reads "FomoA" (the capitol "A" in cursive) anyone have any experiance with this?? I called and asked what was up and the guy copped an atitude with me for just asking a question....I also asked him before I ordered if they knew where the OIL PAN I was about to order was made & they said they had no idea....well, it took me taking the pan out of the box and looking at the little sticker on the plastic bag indicating that the pan came from Tiwan, republic of China!!!
That remindes me of the fellow with the MoFoCo part.<img src=images/icon_smile_big.gif border=0 align=middle>
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This testing procedure is valid for most automotive coils. Using an ohmmeter, check the resistance between the side terminals of the coil. Do this with all of the wires to the coil disconnected. You should see 0.75 to 0.81 ohm of resistance. Then check the resistance between either side terminal and the center high tension terminal. The reading should be 10,000 to 11,000 ohms. Any significant deviation from these numbers would indicate that the coil is defective.
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Getting old is a bitch and I forgot something. There are a few more checks to verify a good from bad coil and they are simple - resistance of ALL terminals to the metal case. Something in the back of my ancient brain says to do them all, but ANY reading is bad. This should be done with a device known as a 'megger', an ohmmeter that is used to read resistance at high voltages - as in a breakdown of insulation.
Jim
Yea, The logo really doesn't look right to me and the guy at VA Mustang said thats how the logos were back then and that it was taken from an original to make this decal many years ago.
At lease it doesn't say MoFoCo!!
In Electrical Engineering terms this is called a Hi Pot test.
It does take a special tester to check high voltage impedance and breakdown of a coil under working type conditions.
A simple DMM (lingo for handheld meter) will only show you if you have an open or a short in the windings - it will not tell you what happens under a load (coil in operation) like a Hi Pot test will.
Being new to this forum I just read this thread.... so I don't know if anyone is still interested in yellow top coils. I have found that the yellow used by most repro houses isn't quite right and to get a good yellow coil can be expensive. Through a lot of searching I found a yellow paint that is so close to original that you have to look at least twice to tell that it isn't Ford and then you may not really be sure... Go to your nearest Cat dealer and ask for CAT yellow 4C-4200. you can make a reasonable looking coil for not much money...
Good info - thanks guys.
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