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MG TD TF 1500 - Re-polarizing electrical system

I need to know what the best advice is on setting up my electrical system. I want to use this inside-the-distributor electronic ignition but I need to know a couple of things first like; what cam do I have and pos or neg ground and should I do this repolarize trick. Fire away folks.

John
John Redman

The Pertonics is what you want, and it comes in positive and negative earth versions.It is a great improvementover a condensor and points. Skip Kelsey (Shadetree Motors) and Joe Curto both stock them. You should get or borrow a copy of the T Restoration Guide from the NEMGT register to look at your cam and determine what you have. Terry
Terry O'Brien

Terry,

I HAVE a copy of the Knudson guide. I'm just having a devil of a time extracting useful information from it (like the info on cams).
John
John Redman

John,
"Pertonics is what you want"...for sure, great little unit and very easy install.
Bud has some good info on his site here:
http://home.earthlink.net/~budkrueger/pertronix_Into_TD.html
As for "Poss or Neg"....we seem to be split on that one...my TF was "partly done" when I purchased it so I went with Neg ground system....I just feel safer that way.
Cheers,
David 55 TF1500 #7427
David Sheward

I really need to know more about repolarizing. Because of the circumstances of my purchase of this car and what went wrong with an "excellent driving car" that got two miles before overheating and then burning out the generator when I put in a new battery which may or may not have been reversed from the battery that was dead. Anyhow, I do not envision putting in a radio (who can hear it anyhow) but I guess that there are other considerations. I have not purchased the Pertronics system yet, so, I am not foreclosed by that, yet. Lets hear it, please.

John
John Redman

John,

Look at your battery! Which post (+ or -) is connected to the ground cable that connects to the wall of the battery box? This tells you if +, then positive ground as from factory. If -, negative ground and may need to polarize generator ( if so you may also need to reverse the leads to the ammeter if not done by previous owner).

Run the engine, does the ammeter show charging? If so you are polarized correctly.

You have to be sure the generator is polarized the same way as the battery is placed or you will burn up the generator and/or the regulator.

Disconnect the field lead (small bolt) from the generator and the large lead (armature), run the engine, and connect the black (- lead) of a voltmeter to the large (output) bolt on the generator and the red lead to ground. (If the voltmeter reads correctly (about 1 or 2 volts) then the generator is polarized for positive ground. If you have to reverse the leads then it's negative ground.

check then that the battery is polarized the same way, and that the ammeter is connected correctly (look at the terminals on back they are marked + & -), if it reads a charge when runnung it's OK.

I hope I have said the above clearly enough,

If you look on Page C.12 Section C.14 of the TD/TF Workshop Manual you can see a picture of the cams in question in the distributor (Needed info for electronic ignition) Distributor Model D2A4 # 40162 and 40367
40162 E and later have high lift cams as do all 40367 and 40637 A. You have to look and compare picture to identify the symmetric and asymmetric cams.
The magnetic sleeve has to fit correctly over the cam in order to lock in place.
Don Harmer

from the Y-type website "technical centre":

Polarising a dynamo
Question: How do I polarise a dynamo?

Reply: To polarise the dynamo Use a small piece of wire and momentarily (about one second) touch it between the regulator terminals marked "Al" and "F" or the way I do it get a long piece of wire from the 'LIVE' side of the Battery and touch the other end on the small terminal on the dynamo. It will make a few sparks so don't think you've hurt something. (John Arkley)

Willem van der Veer

Thanks all, I have the middle one (only can tell by the location of the slot). STILL have not made up my mind on POS or NEG ground, though.

John
John Redman

This thread was discussed between 17/04/2004 and 20/04/2004

MG TD TF 1500 index

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