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TR2/3/3A TR3 Distributor test

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TRclassic3

TRclassic3

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I was using some directions on setting the static timing by using a 12 v lamp(continuity light) to identify the moment the points open. With one end to ground, and the other to the moveable points arm the lamp would light when the points begin to open. Points closed, no light. This of course with the ignition switch on, motor not running.
Now following that concept, does it make sense that you could do the same basic test using a multi-meter set to voltage (say 50) and the ignition switch on, one lead to ground, the other to the moveable arm. Should you only get voltage with the points open? When I do this I get 12 volts both with the points open and with them closed.

Comments please
 
Sounds like something is not being probed properly, or possibly a short.

Voltage travels from the igntion switch to the sw terminal of the coil, through the primary windings of the coil, out the cb terminal down the pigtail, through the little block to the connector on top of the points where the condensor is attached, when the points are closed the voltage goes to ground through the points(and condensor). When the points open the voltage magnetic field collapses in the coil, triggering the induction in the secondary winding of the coil. Make sure the points are insulated(the post on the heel of the points should be grounded to the bottom of the points, but the swing arm should not ground(continuity if you want to use the multimeter) when the points open.
 
Ron

So if I set the meter to continuity, and do the same thing, and I show continuity regardless of whether the points are open or closed, then I have a ground problem? Sorry for being so thick.
 
yup. common places to look for is the primary pigtail that goes from the coil to the points, where it enters the distributor, the point post, or condensor. I would recommend isolating downstream, coil sw to coil cb should be some resistance, but less than 20 for a 12 volt system. cb to point connector,(unscrew or unbolt the wire and eyeball it closely, might be insulation worn). Un fasten the condensor and see if the circuit opens, a lot of condensors short out.
 
TRclassic3 said:
Ron

So if I set the meter to continuity, and do the same thing, and I show continuity regardless of whether the points are open or closed, then I have a ground problem? Sorry for being so thick.
Click to expand...

Not necessarily. You might have a sneak circuit. You need to disconnect the points to eliminate a sneak circuit if you want to use the continuity function.

I need to look at a schematic.

Ron, It hurts me to say it, but I have to whomp you up side the hay-id for saying voltage travels. Sorry.
 
TRclassic3 said:
Ron

So if I set the meter to continuity, and do the same thing, and I show continuity regardless of whether the points are open or closed, then I have a ground problem? Sorry for being so thick.
Click to expand...

Have you disconnected the small wire running from the coil to the distributor (should be white w/ black stripe)?

If not then you will still get continuity with the points open.

The reason you still got 12V in the first set-up (though the lamp went out) is another matter relating to current but I won't try to explain it since by switching to a continuity you are using what I think is the best technique.

Personally I use an audible device for that test so I can hear when the points open and keep my eyes on the timing mark.
 
I had not disconnected the LT wire from the coil to distributor. Oh well, back to the garage. Thanks for the info.

Audible huh? Gee I could have had Dr John hang onto that wire yesterday while I cranked it over. Bet that would have been audible /bcforum/images/%%GRAEMLIN_URL%%/crazy.gif
 
Your original premise of using a voltmeter instead of a test light is valid. Both should give you the same results.

I've used voltmeters to set static timing. Make sure it is set to DC voltage. Why you got another result is confusing. Did you re-try it with the test light??

BTW, when I hook up the light or voltmeter, I hook one lead to ground. Then I hook the other to the connector on the coil with the wire going into the distributor. This way you don't have to think about which arm of the points to probe.
 
I just checked mine. I get voltage at the coil low tension lead when the points are open and no voltage when the points are closed.

The makes sense to my poor befuddled brain.
 
Art and John
I think this lends credence to there being a problem. I get voltage regardless of whether the points are open or closed.

I'll verify again in a few minutes
 
If that's the case, then either the points aren't really closing, or your greasy fingers got schmutz on the points, preventing them from making contact. /bcforum/images/%%GRAEMLIN_URL%%/wall.gif

Try running a point file or some fine emery between the point contacts to clean them off.

One more thing I just thought of. There is a small ground wire that attaches to the distributor plate where the points are attached to and goes to a screw in a notch on the distributor housing where the cap fits in. Check that wire. Maybe it broke or came loose.
 
OK, I am offially go whacko. When I do the test now everything seems OK. That is, I get voltage when the points are open, no voltage when closed.

Is there anything that could cause results to fluctuate? Of course, even though it seems to test OK it still won't start.
 
Driving my wife's 1963 Vauxhall Victor to Cape Cod in about 1967, every time we hit a heavy bump like crossing a railway level crossing, the engine cut out. We'd stop and then it would be OK again. I found out that the stranded wire in the distributor that is covered with a braided cotton cover - well all the strands had broken and when we hit a bump, we had no juice. After stopping the broken strands were touching again.

Check the insides of this wire for severed strands.

Gremlins are everywhere. Better you get rid of them before you leave on a trip.
 
martx-5 said:
One more thing I just thought of. There is a small ground wire that attaches to the distributor plate where the points are attached to and goes to a screw in a notch on the distributor housing where the cap fits in. Check that wire. Maybe it broke or came loose.
Click to expand...

This is the wire I sugested you check yesterday. I agree that something as simple as this could be the problem. Especially since you might have hit it with your probe or compressed air blast. They can become very delicate and break.
 
Following on the coattails of the last two responses I'd probably want to check the continuity of each wire while gently moving them around. Any chance that you have an old style point set with the steel (conductive)rather than later nylon spring post and that you might have inadvertently gotten the hot wire on the wrong side of the insulator.
Tom Lains
TS8651 & 58107
 
I've checked that wire and yes it sure is delicate. The cloty cover is in bad shape. The little wire seems ok but not sure. I found one to replace it with in my pile of stuff from the PO but how do you do that? The one end is held bu a one way screw?
 
Sure does, all the little atoms bumping up next to each other; the protons and neutrons just pushing and pushing each other, get all warmed up and overheated and then they travel. I'm sure you've seen the sparks?

Okay, I should have said the path of current flow, and we all know that it isn't the direction we think it is. Right?
 
Ed - didn't this all start when you were using the Pertronix setup? The problem existed before you put the points back in.

I'm still thinking loose/corrupt wires, either on the dist and/or coil. If there's plenty of gas going through the carbs, and the engine does run for 20 seconds before dying ...

And you replaced the coil?

Tom
 
Yes. The pertronix was in it and seemed to be deliveringin good spark. It was suggested that I change it for points asalthough it was delivering spark it was possible that the spark was being deliverred at thed wrong time. As this change didn;'t help I'm thinking of putting the pertronix back...although I guess it doesn't make sense to do that til the basic problem is resolved.

Yes we tried a different coil (not new). I've ordered a Flame Thrower
 
RonMacPherson said:
Sure does, all the little atoms bumping up next to each other; the protons and neutrons just pushing and pushing each other, get all warmed up and overheated and then they travel. I'm sure you've seen the sparks?
Click to expand...

So THIS is the cause of all those "Emboldened Electrons" I hear so much about!
Who'd a thunk it... wow. /bcforum/images/%%GRAEMLIN_URL%%/jester.gif



RonMacPherson said:
Okay, I should have said the path of current flow, and we all know that it isn't the direction we think it is. Right?
Click to expand...

Right! 50-50 chance and blew it. Can't really be too critical tho. It DOES happen rather quickly.
 
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