[Healeys] Which electronic ignition?

[Chris Dimmock]

Fair call John.
A Lucas healey distributor uses ported vacuum. Which is an SU thing. Vacuum is
taken at the throttle plate. Not the inlet manifold.
These  - ported vacuum and manifold vacuum - are exact opposite vacuums.
Opposite.
That's why you never connect a std Healey Lucas distributor vacuum advance to
a manifold vacuum port on eg a triple weber Healey.
And that's why a factory triple weber Healey had no vacuum advance on a Lucas
distributor.
I use a 23d non vacuum advance distributor, converted to 6 cyl, on my triple
webered healey - which is exactly what the DHMCo did on its race cars.
No idea what vacuum type 3rd party distributors are looking for. And it
depends on your carbs too.
I was just trying to encourage like for like comparison
Best
Chris

Sent from my iPhone

On 17/04/2012, at 1:46 AM, John Harper <ah at jharper.demon.co.uk> wrote:

>
>
> Just a query.
>
> I read in many documents in the past that the vacuum advance in an original
distributor, advanced the spark on light throttle so as to compensate for the
slower combustion burn with weak mixture. Without it higher fuel consumption
whilst cruising is likely. I have experienced this myself when a vacuum unit
has failed when the diaphragm is punctured.
>
> Some of the options listed in previous e-mails do not have any method of
measuring the vacuum from the carburettor so I have to assume that these are
less fuel efficient on long, steady speed journeys.
>
> Any comments please
>
> Regards
> --
> John Harper