Several weeks ago Naomi, I think, and others discussed the matter of poor performance of some newly manufactured ignition "Rotor Buttons" on this forum. I undertook to try and find a Practical Classics magazine item which I thought I remembered on the matter.

I have been unable to locate the particular copy, but have enjoyed being sidetracked in Practical Classics backnumbers!

Fortunately though I have found a reference to the item I provided at the time to the "Rovernet" group and it is, slightly edited, as follows:

It is in part on page 84 of February 2004 "Practical Classics" Magazine, in an item under the "Staff Car Sagas" banner, by the pen (or keyboard) of one Tim Bishop.
Mr Bishop says:

"...And now the 4 Litre R.... which for the last few months has been a pain in my side. It should really feel loved and pampered with its new Minilites ...and its new sunroof. But no, every time it gets hot (and it has been hot) it stops without warning; 45 minutes later it starts again as if nothing has happened. Now the root cause has taken some finding, so take note, all you British straight six lovers!

There is a (huge?) batch of after market rotor arms out there that are not temperature stable. It matters not where you buy them; since Lucas lost the plot it seems they have all been manufactured by a single overseas source. At a certain temperature, the black isolating plastic becomes conductive and your spark goes down the drain. I have had five new rotor arms that behave in this way, the sixth had the decency to fail suddenly, not come back to life, and show a little mark to prove it.

The distributor is directly above the exhaust manifold. So to all those people I inconvenienced the other week on the A45 around Coventry, sorry."

In the same magazine, on pages 96 and 97, in the "Technical Advice" Helpline section, there is an article entitles "Spotlight on ...Rotor Arms"

There is a letter of enquiry from a reader, one Keith Higgins, Middlesborough, who says, in brief "...I've had this fault for ages - a while after setting off, the car splutters and then stops quite suddenly. I've replaced the coil, condenser, plugs, points, distributor cap, leads and rotor arm.
I've finally convinced myself that it keeps shorting through the rotor arm because if I swap the arm for an old one it works OK again - but only for a while. The best I've had out of a rotor arm before the problem re-occurs is 1,000 miles; the worst only 35 miles."

The reader goes on to say that the fitting of an electronic ignition to dispose of the points has made no difference to the problem.

The Practical Classics response was, in essence

"...I'm sure the problem is down to a dodgy rotor arm - read my saga on page 84 to discover the possible extent of this problem!
Strangely, rotor arms seem to have only given trouble over the last couple of years. You could buy five rotor arms and expect one good one (maybe). As soon as you find a good one, it should last as long as the car. I'm making my own using a modern material. First one is currently trialling on my Princess...."

There is an illustration of some rotor arms, including the home made effort on the adjacent page.


I don't know how accurate the above all is but add it as grist to the mill.

In the April "Practical Classics" in response to a further reader query, the material used for the home made effort is revealed as "Delrin"

I hope the above is of some interest.

Regards,

Barry R