Change in Wiring - FSB 11/29 p.390

[Badpuppy]

Got my copy of Ford Service bulletins yesterday. I found the "Change in Wiring" description reads like Sanskrit, so after I figured out what it was trying to say, I thought I'd pass on my translation.

First, disregard Fig. 784; it's drawn incorrectly. If wired as shown the coil polarity will be reversed.

The change can be made by referring to Fig. 785 and simply disconnecting the black wire from the right-side junction box post and moving it to the left one. This leaves only the two yellow wires on the right and everything else stacked on the left post with the two yellow/black wires.

The result after this change is that the ammeter now properly shows only battery charge/discharge current.

The text attempts to describe the change from a troubleshooting standpoint, i.e., with the cutout open.

You're welcome.

[Tom Endy]

The service bulletin language may be difficult, but the change offered a desirable diagnostic tool. With the wiring change as you are attempting to start the car observe the ammeter as it will be swinging back and forth past the zero center before the car starts. With an original un-damped meter each time the ignition points close the needle moves toward the minus; when the points open it swing back toward the zero, but because it is un-damped it swings past it toward the plus. What it is telling you is that the primary ignition circuit is working properly.


I was rolling down the road in my Victoria one time and the engine quit. After I rolled to the side of the road I attempted to start the car and it would not start; but I noticed the ammeter would swing back and forth and it told the me the battery was still attached to the car, the primary circuit of the coil was intact, the wiring was intact, the ignition key was working, the pop-out cable was not open or shorted, nothing inside the distributor was open or shorted, and battery voltage was reaching the points. This is a lot of good information.


When I open the hood I found the ignition high tension secondary wire had come loose and fallen out of the bottom of the coil.


Tom Endy

[Badpuppy]

Thanks, Tom, you convey the message a lot better than the Ford guys. I was describing the change from the technical side, you describe from the practical, which is probably a lot more useful to the average joe.

I might add that folks might want to mark up their copies of the wiring diagrams.

[Jim/GA]

Originally Posted by Badpuppy

Got my copy of Ford Service bulletins yesterday. I found the "Change in Wiring" description reads like Sanskrit, so after I figured out what it was trying to say, I thought I'd pass on my translation.

First, disregard Fig. 784; it's drawn incorrectly. If wired as shown the coil polarity will be reversed.

<snip>

Actually, that's not quite true, because Ford also, at the same time, changed to a different polarity on the coils. So that when the black wire was moved to the other side, proper polarity was maintained.

But none of Ford's coils had the posts marked + or -, so it is easy to get it messed up. The coils were spot welded into the mounting brackets, so they could only go one way.

Look in Area 2 of the Restoration Guidelines, on page 2-13, to read more about the coil design change. You might have heard people refer to "slant post" coils and "straight post" coils. That's what this is about. The polarity and which side the black wire connects to is different for slant (first version) and straight.

[Badpuppy]

Ah! Thank you for the clarification, Jim. So the SB was not only unclear, it was incomplete. Argh!

[Tom Wesenberg]

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I have a slant pole with reversed polarity at the terminals, so I'd guess it was made during the transition period. Best to always check with a meter as suggested above.