TR2/3/3A TR3 Distributor Woes

[NickMorgan]

OK guys. I thought I would be cleaver and replace the base plates in my distributor. I used to have a problem that I couldn't get any adjustments at the points and I am pleased to say that the new base plates have resolved this.
However(!!!), having replaced both base plates, the l/t lead, the points, rotor arm and condenser The car now won't start!!
These are all good quality components. Nice red rotor arm, original points, good quality condenser.
I have swapped back the rotor arm and the condenser to the old ones, but still no spark at the plugs.
I switched on the ignition and got 12+ Volts between earth and from both sides of the coil, from the little nut on the points.
I then tried a continuity test with the ignition switched off. This showed continuity between the l/t lead and earth. It also showed it between either side of the coil and earth and, in face, between anywhere on the distributor and earth.
Now I am completely confused. :confuse:
(I did put the little plastic spacer on points in the right place!)
Any help would really be appreciated.

 

[Dale]

Best advice I can give is, don't panic. I would check for spark first and if I didn't have it, would review the installation of the new parts. You've already checked the insulating bits on the points, but could you have insulated the points from the condenser. Just a thought, and you have my sympathies as I just had the same thing with my J-H. First thing I had to do was put the plug wires back on the plugs.(duh)Good Luck

 

[TR4nut]

Nick-

Not an expert (at all!) - but are you seeing any spark at the points when you crank the engine. If no spark, I would guess you indeed have the LT lead continuously grounded for some reason which would prevent the plugs from firing. And I'll shut up now to risk further exposure of my ignorance on the subject!

Randy

 

[sp53]

Make sure you have that little insulator piece in right because if that grounds it will not start

 

[14dna]

Nick;
can you take a pic of the dist and post it?
Sounds to me like the plate in the dist is grounding out and no spark.

let us know.

Dave

 

[TR3driver]

got 12+ Volts between earth and from both sides of the coil, from the little nut on the points.

Nick, are you saying you found 12v between the nut on the points and ground? If so, the moving point plate is not grounded, which likely means the ground lead for it is missing or broken internally. Since it's forced to flex every time the vacuum advance moves, the wires inside do sometimes break with no visual indication.

I would proceed with the key on and the points closed; using a test lamp to check for voltage to ground. Continuity testers can sometimes be fooled when doing "in circuit" tests. If there was voltage on that nut, then next check the moving point plate, then terminal where it's ground lead is attached to the distributor body. If you are still finding 12v at every point, then check the distributor body itself, and the clamp that holds it to the pedestal.

Sooner or later, you're going to no longer find 12v, then you know the problem is between the place that does, and the place that does not.

 

[TR3driver]

Oops, slight correction to above. That nut is attached to the fixed point arm rather than the moving plate; so it may be that points are not in good contact with the moving distributor plate. Also, the first dizzy I looked at from the parts bin had a plastic post!

So, follow the 12v on the wire, to the moving arm (contact breaker lever in the attached diagram) then the fixed arm of the points (aka fixed contact plate). Then proceed to the moving plate (moving contact breaker plate), as above.

 

[NickMorgan]

Thanks for all the great advice guys. I will have to wait until I get home to have another play with the car.
Every part shown in the picture above is new on my car, so I must have fitted something wrongly.
I think that the multi meter has probably confused my already muddled mind. In my view the Contact Breaker Base Plate is earthed to the distributor body. The Moving Contact Breaker Plate is earthed through the little wire to the distributor body and also earthed as it touches the plate below. Therefore the Fixed Contact Plate is earthed as it is screwed to the contact plate.
I was supplied with an original set of points, so there is a little fibre washer on the post that holds the spring and the post that holds the other end of the Contact Breaker Leaver. In my muddled mind that means that the Contact Breaker Lever and the L T Terminal should not be earthed when the points are open.
I then get very confused with the continuity tests, but maybe as suggested I should use a 12V lamp instead.
I thought that I had found the fault yesterday when I noticed that the washer under the screw holding the Fixed Contact Plate was touching the end of the spring on the Contact Breaker Lever. I wonder if that could have caused some damage elsewhere?
I will certainly let you know what the problem was when (if) I solve it! It is always these silly little problems that have me dumbfounded!

 

[TR3driver]

In my view the Contact Breaker Base Plate is earthed to the distributor body. The Moving Contact Breaker Plate is earthed through the little wire to the distributor body and also earthed as it touches the plate below. Therefore the Fixed Contact Plate is earthed as it is screwed to the contact plate.

That is all correct, except that the contact between the two plates is not reliable (hence the ground lead). There are actually little plastic buttons between the plates, and should be lubricant as well.<div class="ubbcode-block"><div class="ubbcode-header">Quote:]In my muddled mind that means that the Contact Breaker Lever and the L T Terminal should not be earthed when the points are open.[/QUOTE]Right again. Earthed when points are closed, not earthed with points open.<div class="ubbcode-block"><div class="ubbcode-header">Quote:]I thought that I had found the fault yesterday when I noticed that the washer under the screw holding the Fixed Contact Plate was touching the end of the spring on the Contact Breaker Lever. I wonder if that could have caused some damage elsewhere?[/QUOTE]No different than having the points closed, so very unlikely it caused damage elsewhere.

But having fixed one problem, you should probably recheck the voltages. No doubt the symptoms will have changed.

Nothing wrong with using a voltmeter instead of a test lamp; just stay away from the continuity measurements.

 

[NickMorgan]

Thanks everyone for your input. The problem is now solved. I put everything back together and tried all of the electrical tests that Randall recommended. I managed to get 12V all of the way from the coil to the moving side of the points. Then when I tested across the closed points I got nothing. Turned out that the NOS points had a waxy protective coating on their faces, which I could scrape off with my nail. Once back in I got a weak spark at the plugs, so a little emery paper cleaned up the contacts further. The car was still pretty reluctant to start, but I think that was probably down to the battery being a bit low.
I am glad that it wasn't something silly that I had done! Thanks again for the help. :banana: