MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - Rotor Arms...again!

Judging by the amount of archive material on the subject of rotor arms, this is probably "old hat" to many of you, but it was news to me on Sunday morning when, after running faultlessly for about 30 miles, my engine decided to switch itself off. No misfire or stuttering, it was just as if an invisible hand had reached in and turned the key. I had fitted a Lucas sport coil about six weeks ago, and having read about failures of these on this forum, decided to carry my old coil as a spare. So as soon as I came to a halt and realized it was lack of sparks, I changed the coil for the spare. This made no difference and I eventually came to the conclusion that the fault had to be the rotor arm, an item I was not carrying. There was no obvious damage to the rotor arm, it looked as good as new and came with the 25D distributor bought from Moss about two years ago, but when I offered it to my nose for examination, it smelt of burned bakelite.
A passing farmer and MGB owner kindly did a six mile round trip to his home and came back with a spare rotor arm, which was just as well because when the RAC man turned up he didn't have one. Anyway, the car ran perfectly for the rest of the trip. Later that day I was told that modern rotor are a load of rubbish and "always carry a spare". Well, in 33 years of driving and maintaining MGs I have NEVER had trouble with a rotor arm, except perhaps a "missing" one when I forgot to fit it!
It would appear that the plastic that rotor arms are made of these days contains too much carbon (to make them black) and the spark simply finds a way through it, decent ones are hard to find here in the UK, so I have ordered a pair of rotors from these people http://advanceddistributors.com/index.htm hopefully they will be better!
This post is to help those, who like me, have never encountered this trouble before.
Lindsay Sampford

Lindsay - "I have ordered a pair of rotors from these people http://advanceddistributors.com/index.htm hopefully they will be better!"

You took the right action. Jeff has found a source for good rotors that don't fail in the first few months of their life. Cheers - Dave
David DuBois

That's good to know, thanks Dave.
Lindsay Sampford

Hi Lindsay , this sounds just like the Holiday to Yorkshire that nearly did not happen !! we had the same things go ,3 rotor arms , coil & regulator almost lost the holiday , came home bought a petronix set up & have never had a moments trouble , from 01/06/09 France Switzerland & home& up to Silverstone 3000 miles, we now feel very confident & relaxed to take the A any place , Angouleme in September & more in between ,go electronic & really enjoy the A
Colin
colin daly

I was thinking about that Colin. Am I right in thinking that it would be fairly easy to switch back to points and condenser on the side of the road if the thing should fail? I also notice that -ve earth ones are £20 cheaper than +ve earth ones; glad I converted, hehe!
Lindsay Sampford

Lindsay - Having worked nearly 40 years in the electronics trade, I've learned to never trust the stuff (I made my living fixing it when it broke). I switched to the Petronix on both our TD and MGB, but I carry a base plate with pre-adjusted points on them in both cars so I can always get home. Cheers - Dave
David DuBois

Colin and Lindsay

Converting to an electronic ignition does not solve the issue that is the subject of this thread, it still needs a rotor arm!

David mentions the easiest way to convert back to cb if the electronic systems fails, otherwise it's probably bit of a fiddly job by the roadside in inclement weather. Alternatively, carry a spare dizzy, which is what I tend to do. Fingers crossed my Petronix (Aldon Ignitor) has been faultless for the past year or two.

Steve
Steve Gyles

Funny how these threads seem to go off subject, but interesting. Yes I do know that the rotor a different issue and really all that pertronix (not Petronix!) does is elliminate any problems with points or condenser.
Lindsay Sampford

Hi Lindsay,

Would I be right in thinking you were on the way to Charlecote on Sunday?

Did you make it in the end?

Chris.
Chris Bond

Yes I did, unfortunately I didn't meet anyone on this site because I didn't know who I was looking for, We must wear name badges! Saw Colyn's nice bumperless Twin-camish monster...but didn't see him! Never mind, great drive and terrific line-up.
Lindsay Sampford

Same here - next time I'll wear a badge.

Here is a picture of the lineup.


Chris Bond

This thread was discussed between 03/08/2009 and 04/08/2009

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.