Did you know?

[Keith Clements]

The position of the rotor arm relative to the cap posts is important. Make sure the spark fires across the leading edge of the rotor brass arc. See where the black mark is as this is where the spark normally goes when under power. If the wrong distributor or a mongrel of a distributor is installed it may not be, and either the spark fires too early on vacuum advance or too late at static and misses the brass arc.
Marking the position of the posts onto the distributor base and then looking at the position of the rotor at tdc will check.
The pictures show the anticlockwise and incorrect clockwise rotor.

[David Morris]

Hi Keith,

Good point about seeing where the 'evidence' of spark erosion is on the rotor arm by visable inspection.

But having had bad experiences with black rotor arms, I would spend a bit more and fit a red one. Much less likely to be dodgy!

All the best,

David

[Forumadmin]

There were some black ones produced in China that were made from an incorrect bakelite but the red variety marketing machine has probably tarred all black ones with the same brush.

[David Morris]

Hi Keith,

You are probably right, but in this case, I suggest that the supplier is the best guide. A black one ( or even a red one! ) that comes from an unknown supplier is likely to be suspect. The cost differential is not much, and for the trouble a duff arm causes, I would always go for a reputable UK supplier and a red one at that!

All the best,

David