Original distributor

E

Ed

Member
I replaced the points and condenser in my Model A distributor. The distributor has all the original style parts. When I assemble the upper plate into the distributor housing, the wire that attaches to the points is grounding to the distributor housing or the lower plate. ( I can't tell which one). (I am showing continuity between the points arm and the case). I have attempted to bend the metal tab that attaches to the points several times without success. I have also placed a piece of paper to open the points while testing.

I do not understand why this is so difficult. Is there something obvious that I am missing?

Thanks in advance for your comments and suggestions.
 
Ed, not trying to be a Smart A$$ but are you checking it with the points open? If you are checking with the points closed, you will show continuity.
 
No offense taken. Yes I have the points open when testing. That is what I meant when I mentioned using a piece of paper to open the points while testing.

The exploded view helps a lot. Items 20 and 21 are present and accounted for.
 
One of the most difficult aspects of the original distributor is the wire that connects the lower plate with the upper plate. It is hidden from view when the distributor is assembled and can easily be shorting things out.

Over the years I have taken hundreds of distributors apart and have found any number of ridiculous attachment wires installed. Some looked like they were cut from a bob-wire fence.

This attaching wire must be very thin and be composed of multiple strands of fine wires. This will allow it to flex and move in a reasonable manner each time the driver adjusts the spark advance lever on the steering column.

Bratton's understands that and offers the correct wire. I have found it more cost affective to purchase their lower plate, which is very good quality, with the wire already attached. When you install it you have to route the wire so that it does not bind when the spark advance lever is manipulated. When installing the assembly the lug that attaches to the bottom of the points arm should be bent straight up so that as the top plate is rotated by the spark advance lever it will not short out against the casting.

You have done the right thing by placing a piece of paper between the points to check for a short. You should be able to operate the spark advance through it range without encountering a short. A short is detected with an ohm meter. Connect the ground probe to the casting and the other probe to the arm of the points. Rotate the top plate with a piece of paper between the points.

it can be a tedious process. Another thing to consider is that reproduction condensers are slightly longer than the originals. This can push the front end of the condenser up against the later 31 casting as they are more robust than the earlier ones, and cause them to short out.

Tom Endy
 
Is the cable screwed in Too far?
2 or 3 turns is enough.
I saw once set of points where the movable arm spring rubbed the cam.
 
Thanks for the replys.

Tom E. :
The problem you are describing is the very problem I am experiencing. When I install the upper plate I am showing continuity between the points arm and the distributor housing. I am certain the problem lies with the wire and or connection to the upper plate. I have removed the distributor from the vehicle for easier access for testing.

I just ordered the hardware kit, upper and lower plates, and the points and condenser. I have never had any problems with this distributor in the decade that I have owned this pickup. The problem showed up after replacing the distributor cam, and points and condenser, after discovering a flat lobe on the distributor cam.

Tom W.:

Backing out the ignition cable is the first thing I tried. Now I have removed the distributor from the vehicle, and the cable is not attached to the distributor.

The reason I replaced the points was due to the wear block being excessively worn. The arm of the points was getting close to touching the cam.

Again, thanks for your replys. Sometimes it just helps to discuss these things with others.
 
As mentioned by Ed, it appears you are missing the insulating washer on the bottom of the movable section of the points.

If you look at the drawing 1955cj5 posted you will see the threaded post of the points (#18) then there is a small insulating washer (#20) that fills the gap between the insulating section and the metal section of the upper plate. Next, there is a larger diameter but thinner insulating washer (#21), the wire flag (#22), and then the nut (#23). I have seen a small nut used in place of the #20 washer.

With these in place, the bottom plate wire is insulated from the upper plate.

Also, check that the wire #21 is not touching the metal on the bottom plate #13.
 
Try checking continuity with the condenser grounding screw off the back of the condenser. I had the same problem and it turned out to be a bad new condenser.
 
Mike V.:

As I said in my previous message in this post, items 20 and 21 are present and accounted for. I do not have any continuity, between the upper plate and the points arm, unless the upper plate is installed in the distributor housing. Without the plate being installed into the distributor housing, and the points being held open with a piece of paper, I have no voltage to the grounded portion of the upper plate. Therefore the points are insulated correctly.

So I am fairly certain the problem lies with the metal flag of the wire that attaches to the bottom of the upper plate touching either that lower plate or the distributor housing. As Tom Endy mentioned in his reply, neither of these areas are visible when the top plate is installed.

Western77:

Before removing the distributor the condenser was checked in the manner you suggested. There is no continuity when performing this test.

Again, thank you for your replys. I appreciate your suggestions and help. Sometimes a guy can get so focused on the problem, that they lose the objectivity required to solve the problem.
 
On the wire: In a PINCH, I've ripped apart a FLAT extension cord & used it for a "pigtail"! They're usually soft & flexible & contain MANY multi-strands.
It's also good for making up JUMPER wires & replacing funky wires on your OLD Signal-Stat Test light, or other test equipment!
Bill Makeshift
 
I finally have some success ! After disassembling the distributor for the upteenth time, and tweaking the bend of the flag on the end of the wire, I am able to move the upper plate without grounding it to the distributor housing.

Family activities will keep me from doing the reinstallation of the distributor until later this week. However, I am now confident I am headed in the right direction.

Again, thank you all for your helpful suggestions and comments. It is greatly appreciated!
 
You must log in or register to reply here.
Back
Top