Heres how to do a simple test on your rotor arm, the rotor arm can short to earth and stop your car dead in it tracks, so how do you do a quick test on your rotor arm.
Rotors arm suffer mainly with 2 things, a loose brass segment with in the bakealite construction, or small cracking in the bakelight.
If either is visible then replace the rotor arm.
There may be a issue when the electrical nonconductivity of the bakelight fails due to spider webbing in the construction or small cracks.
To test if your rotor arm is faulty
Remove the coil lead from the centre of the distributor cap
Remove the distributor cap from the car and tuck back out of the way
Get someone to crank the car over while with insulated pliers you hold the coil lead about 3mm away from the copper segment of the rotor arm. if you have points rotate the engine over until the points are closed and then flick the points open with a screwdriver.
If on either test you get a spark from the coil lead to the centre of the brass segment of the rotor arm, the rotor arm has lost its nonconductivity and there is a path to earth through the bakelight.
Fit a new rotor arm.
There are lots of cheap rotor arms from the far east causing problems, and the Distributor Doctor has had a batch of red rotor arms made to original specification, the red ones on ebay are not the same ones be warned.
Edited by KernowCooper, 15 August 2013 - 07:33 PM.
