Distributor explanation please?

[malcolm]

I took the top off my distributor (to be nosy) and don't quite understand the layout.
I have a rotor arm, fed by a brush from the coil, which feeds the 6 contacts inside the cap; but there are no contact breakers. The end of the rotor arm instead brushes against the red nylon fitting - what does this do? (See pic)
Presumably this is some electronic modification to do away with contact sets, but how?



Also, does the advance/retard dial still do anything, or is that now non operative because of the changes in the distirbutor?

Thanks for any help.

[Heuer]

It is a simple and very efficient way of getting rid of the points and condenser and uses the Hall effect. The black 'rotor' contains a magnet and as it passes the red 'switch' it creates a pulse which is translated into a make/break by the electronics to energise the coil. To all intents and purposes it works just like a contact breaker set but is more reliable and never needs adjusting other than possibly the timing. The advance/retard works as per normal. The system does not produce an electronically enhanced spark like some others (Petronix, Mallory, 123) but it is still very efficient even if you are going racing.

[malcolm]

Right, got it thanks. No need to upgrade then from what you are saying. I also have the Spitfire spark enhancer fitted between the distirbutor and coil. I didn't know what it was, but saw it being demonstrated at the Cressing Temple show. It produced multiple strong sparks across the plug rather than the normal single spark, and looked impressive - don't know if it is!

[Heuer]

Spark enhancers are a bit 'snake oil' in my opinion. Sounds good but you only need one spark for ignition although bigger and multiple sparks might aid a poorly designed engine or worn to burn fuel more efficiently. The XK engine is not one of those. None of the mainstream car manufacturers appear to use them.