[Healeys] Distributor Swap

[Harold Manifold]

Simon,

I think the answer is "it depends". I changed my Lucas DM6A to a 123 when I
restored my car as the Lucas distributor was being used as a blender for
small parts that had fallen down into the weights over the years.

I wanted the distributor cap and plug wires to be in the approximate same
position as the Lucas DM6A so it looks the same at first glance and the
routing of the plug wires is close to original. The only way I could do
this was to change the position of the distributor drive gear with respect
to the cam until it would line up with the drive dog on the bottom of the
123. If I put the DM6A back in the car the timing would be way off. If the
hole for the drive dog peg was in the same position relative to the
position of the rotor on the 123 as the DM6A then they should be
interchangeable.

If you don't move the drive gear when you set up the 123 then the DM6A
should go back. The issue you may have is the plug wires don't look very
tidy with the 123. If the rotor is pointing at the same cylinder, even
though it may be in a different position, for both distributors then it
should work. Pack your timing light as well.

Harold




On Sun, Mar 26, 2023 at 12:57 PM Simon Lachlan via Healeys <
healeys at autox.team.net> wrote:

> I should probably be able to work this out for myself, but – just to be
> sure – I’m asking the experts.
>
> Talking about a Lucas DM6a in a MkII BT7. And a 123 alternative.
>
>
>
> So, I have a 123 installed in the car and a Lucas DM6A, complete with
> Pertronix, in the boot. (Trunk!) Yes, both distributors have the correct
> “Drive dog(?)” on the bottom. (Part 25 in the attached pic).
>
> Thus, it is mechanically possible to remove the 123 and drop in the Lucas
> in its place.
>
>
>
> My question is this……if I manage to accomplish this without messing up the
> timing ie rotating the distributors in the clamp, will everything line up
> and the engine fire up?? I hope that the Drive dog will/can only slot into
> one position and that will be the one and only correct position. If you see
> what I mean?
>
>
>
> I hope to be able to carry the Lucas as a spare “get you home” and,
> likewise, hope that it’s a  straight swap without having to frig around
> with the timing.
>
>
>
> Am I correct? It’ll be a straightforward swap or will it turn into a
> complicated roadside tune-up??
>
>
>
> Thanks,
>
> Simon
>
>
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