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MG TD TF 1500 - Distributor cam profiles

Once more I am in search of knowledge on my TF 1500, engine XPEG nr 1292, produced 13-15 October 1954; for which I am planning to order a pertronix kit.

On looking down on the distributor cam i feel it is difficult to tell whether this is a symmetric, asymmetric or high lift cam. The Moss Motors catalogue indicate that the later MG TD and some of the MG TF had a symmetric cam but that the later MG TF had a High Lift cam.

It seems I need to know this before I order my Pertronix kit. I therefore enclose a close up picture of my distributor and ask you to please help me out on the cam type issue.

in the rather cramped confines under the TF bonnet the following is visible from above , stamped into the body of the distributor facing away from the engine: D2A. Probably part of a longer ID number.



regards, Jan

Jan Kristoffersen

Jan, I always had difficuly in determining the type cam I had until I studied Fig. C.20 on page C.12 of the factory shop manual. I finally realized that the slot for the rotor locator is cut in different places relative to the cam contour. Your photo has dark shadows that make it hard to make a decision but it looks like you have a high lift type. After all the years since the car was assembled, you cannot be positive that the cam is still the original but the probability is high.
I hope this helps.
Jim Merz

From the one cam lob that is visible, I would agree with Jim that you do have a high lift cam.

George
George Raham [TD4224]

Any chance you could clean it and the surrounding area up a little and snap a couple other pictures? The high lift is almost square, and I just can't really make out the contour. The manual also says originally any distributor part # ending in "E" or any letter after originally had high lift cams, but the cam could have been changed at some point. George
George Butz

Jan - you have a high lift cam profile. Here is a picture of the three different cam profiles. Note that the symmetric and the high lift profile look very close, but it you look at the locating slot for the rotor in addition to the profile, you will see the difference.

David DuBois

Thank you all for responding; I have been out in the garage and checked baser on your info and I definitely have a high litt cam.

The internet is fantastic!

Regards, Jan
Jan Kristoffersen

What is the benefit of one over the other? PJ
P Jennings

PJ - You should address that question to Jeff Schlemmer at Advanced Distributors jeff@advanceddistributors.com Cheers - Dave
David DuBois

PJ,

Acording to this web site " The high lift cam was fitted to later distributors to improve ignition system performance and increase contact life."

http://www.mg-tabc.org/techn-up/distributor.htm

Jim
James Neel TD28423

Hello again,

Here is a much better picture of my distributor internals, clearly showing what muust be a high lift cam


regards


Jan

Jan Kristoffersen

Jan, I'm a strong advocate of the Pertronix Igniter. But-- see http://www.ttalk.info/Failure.htm . I suggest that you might want to check the height of your rotor and possibly shave a bit off. Bud
Bud Krueger (TD10855)

Somewhere I have the dimensions of the cams, can't find them now but I seem to remember that they came from Bob Gruenau (sp). Maybe he could jump in here and supply the dimensions.
Cheers,
Bob
Bob Jeffers

See my earlier post with web page, information on cams is there.

Jim
James Neel TD28423

Yupp that's just the info I was refering to. With a caliper and those dimensions you can determine without a doubt the cam you have. Also you can determine if there has been wear due to lack of lubrication.

Thanks James Neel. Sorry Bob I spelled you name wrong.
Cheers,
Bob
Bob Jeffers

According to some old literature from Moss, the symmetric cam measures .661 inches flat-to-flat. The high lift measures .640 and the asymmetrical is .704.

Ben
M Prince

This thread was discussed between 24/11/2010 and 28/11/2010

MG TD TF 1500 index

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