Subject: Re: [Mgs] points

From: Richard Ewald <[email-masked]>
Date: Thu, 9 May 2013 09:32:55 -0700

Is the dwell meter analog or digital?

On Thu, May 9, 2013 at 9:00 AM, Monte Jane Morris <[email-masked]>wrote:

> I have an inductive timing light and a dwell meter. I need to determine
> when my points are open or closed. Can I use one of the above to do this
> and if so, how?
>
> Where exactly do I hook the alligator clips to use each one?
>
>
> Thanks,
> Monte 79B with points dizzy
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From: Steven Trovato <[email-masked]> mail.com>
Date: Thu, 09 May 2013 12:48:06 -0400

Check out this video on static timing an MG:

http://www.youtube.com/watch?v=hpp67aqwM2Y

For what you want to do, it might be possible to use a dwell meter, 
depending on the settings available, but a simple test light is 
easier.    Light on = points closed.  Light off = points open.

-Steve Trovato
[email-masked]

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From: Barney Gaylord <[email-masked]> mail.com>
Date: Thu, 09 May 2013 11:53:46 -0500

Youi need a test light.  Very cheap tool.  See here:
http://mgaguru.com/mgtech/tools/ts129.htm

The contact points are switching the coil wire to ground.  With 
ignition on, when points are open there will be power on the wire 
from coil to distributor.  When points are closed the wire is 
grounded and will have no power, 0-volts, no light.

Alternately, you can disconnect the wire from coil to distributor, 
connect the test light to a live power source (lower fuse for 
instance), and touich the ptobe to the distributor terminal.  When 
points are closed it complets the circuit to ground, and youie get light.

You can also test points with an ohm meter connected between the 
distributor input terminal and ground on the engine block.  With 
points open it will read 50-megaohms (open circuit).  With points 
closed it should read 0-ohms (short to ground).  Resistance with 
points closed should never be higher tham 1/4-ohm 
(250-milliohms).  If resistance is too high you need to clean the 
contact points or fix a faulty connection.  It couid be corroded 
points, or a dirty wire connector, or bad contact between distributor 
body and engine block.

At 11:00 AM 5/9/2013 -0500, Monte Jane Morris wrote:
>I have an inductive timing light and a dwell meter. I need to 
>determine when my points are open or closed. Can I use one of the 
>above to do this and if so, how?
>
>....

[email-masked]

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From: Richard Ewald <[email-masked]>
Date: Thu, 9 May 2013 10:07:29 -0700

Steve said:

>
>   Light on = points closed.  Light off = points open.
>
>
>> Barney said:
>>The contact points are switching the coil wire to ground.  With ignition
on, when points are open there will be power on the wire from coil to
distributor.  When points are closed the wire is grounded and will have no
power, 0-volts, no light.

One of these is not like the other.  :-)
You can use a dwell meter if you don't have a test light.  With the points
closed, the meter will read 0 degrees of dwell, with the points open it
will read 90 degrees.
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From: Monte Jane Morris <[email-masked]>
Date: Thu, 9 May 2013 12:33:06 -0500

It's analog.

[email-masked]

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From: Steven Trovato <[email-masked]> mail.com>
Date: Thu, 09 May 2013 13:43:36 -0400

We are both right!  Read the rest of Barney's post and you will see 
the next thing he says is:

Alternately, you can disconnect the wire from coil to distributor, 
connect the test light to a live power source (lower fuse for 
instance), and touch the probe to the distributor terminal.  When 
points are closed it completes the circuit to ground, and you get light.

This is the method shown in the video.

-Steve

[email-masked]

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From: Monte Jane Morris <[email-masked]>
Date: Thu, 9 May 2013 12:55:29 -0500

OK, Thanks.  I do have a test light!
Monte

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