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TR2/3/3A Rotors - TR3A

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Don Elliott

Don Elliott

Obi Wan
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I have been using the rotor shown at the left for a few years. It has a rivet in it and in the past 5 or 6 years, many TR owners have had problems with repro rotors that have a rivet. The two in the center are old ones I used way back when and I carry them as spares - just in case. Notice they don't have any rivets. The one on the right is a new one that I won in as a door prize last year and it has never been used.

Which rotor would you use ?

Notice the lengths of the curved brass ends are all different.

How would this affect the timing if someone switches from a long one to a short one or vice-versa ?
 

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Don, assuming that the key that slides into the slot in the the distributer shaft is oriented the same on each rotor:

The "longer" curved part would advance the timing

The "shorter" curved part would retard the timing

The metal part on the rotor on the right looks like it doesn't stick out as far as the other three. Is this an optical illusion? Looks like they put the rivet in the wrong hole. Would it even touch the contacts in the cap?
 
How does the rotor affect timing?? It's controlled by the points when they open.
 
It doesn't. I suffered an attack of vacancy of the cranium.
 
To answer your question, Don, I would use the rotor that has been working !
No doubt the new one would work fine, at least for awhile, but I wouldn't install it until you have some reason to think the old one might be failing.

The width of the tip is only related to timing in that a long tip allows the rotor to be used in applications with more total advance. Since that's not an issue with a TRactor motor, any of the tip designs should work fine.
 
I have had the 3 of the rotors on the right crack and short out. This was a few years ago all of them did not have many miles on them. I am still using the one on the left that Auto Zone got for me.

Don
 
BobSands said:
Hey Don,... bad rotors are pretty common on TR6's. Found this litlle "tidbit" in "Classic Motorsports". No affiliation, but possibly a new source.https://www.antiquedistributorcaps.com/
Take care Bob
Click to expand...
I wonder if those (from Kip Motors) are the same as sold by The Distributor Doctor in the UK, whose rotors are also sold by at least one other UK vendor that I know of? "DD" rotors have gotten some good writeups in the TR Register's TRAction magazine and elsewhere.

Meanwhile, Don, I'm not sure which of the two center rotors it was now, but I've long kept most of the rotors I've ever had, including several of those long-unavailable "long" rotors, and it was one of those ancient rotors that I stole out of my project '57 Standard Pennant to put in my '62 Herald...when I stole the rotor out of my Herald to get a buddy's MGA running again a couple of years ago. That was the all-too-familiar situation: a NEW rotor crapped out completely. I made the foolish and impulsive (and in anger) mistake of chucking that rotor as far into the woods as I could throw it after putting the well-used Herald rotor into the MGA and starting it immediately! ;-)

Thing is, barring actual physical damage to the body of the rotor or really severe burning of the contact piece, I kinda wonder why people replace them so often? /bcforum/images/%%GRAEMLIN_URL%%/smile.gif
 
Andrew Mace said:
Thing is, barring actual physical damage to the body of the rotor or really severe burning of the contact piece, I kinda wonder why people replace them so often? /bcforum/images/%%GRAEMLIN_URL%%/smile.gif
Click to expand...
How about because damage to the body is not always apparent ? It doesn't happen often, but it does happen even with original-quality rotors. Just like distributor caps, they can form carbon tracks that sap off spark energy. Souped-up ignitions and wide (or worn) plug gaps only make it more likely. That's why most car makers recommend replacing the rotor during a tune-up (although AFAIK Standard-Triumph didn't).
 
Andy - and others too - I went back to the old one with the long brass curved bit and no rivet and installed it and it's working just fine.

Thanks everyone for your input.

Don
 
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