[Healeys] Which electronic ignition?

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Hi Chris,

what do you mean by 'it will do exactly the opposite to what a Lucas/ Healey distributor vacuum advance is designed to do'?

It will not operate to retard the ignition timing. It will advance the ignition timing nearly the same amount when the throttle is not closed. The only difference is when the throttle is closed, when ported vacuum doesn't result in ignition advance while manifold vacuum will do.

The 123 compensates for this, making it compatible to ported AND manifold vacuum.

Eric
Brits 'n' Pieces (Germany)

...
My comment was that I have no idea what "type" of vacuum a replacement/
aftermarket distributor (Mallory, 123 ignition) distributor requires. Are they
designed to use manifold vacuum, or "ported vacuum"? Again, I don't know.
But I'd work it out before I just plugged it in.

Why did i raise this? Because I do know that if you connect the vacuum to the
'wrong' point - e.g if you connect a standard Lucas Healey distributor vacuum
line to the manifold of a Healey it will do exactly the opposite to what a
Lucas/ Healey distributor vacuum advance is designed to do.
Same if you connect a distributor that has vacuum advance designed for
manifold vacuum, and you connect it to the ported vacuum.

Hence the weber comment. How many webered Healeys have you seen with a vacuum
line from a Healey/ lucas distributor connected to the manifold? I've seen a
few. It won't work. It will provide the vacuum operated advance at the wrong
time. It will advance the ignition when the engine doesn't want, or need,
extra ignition advance.
Best.
Chris
Sent from my iPhone