<snip>
> I believe you are incorrect on the need for the cap being a function of
the
> plug gap size, although it is indirectly correct. The optimum nominal
plug gap
> will be about double for a high energy ignition system, either Ford's or
the
> after market units which are much better. It is the high energy Ford
system
> that required the change.
Based on Bob's links, and his earlier comments, the optimum nominal plug gap
is a function of the engine's state of tune and the incoming charge density,
not what you use to light it.
> If you are using a high energy system, the key driver here, you will get
cross
> firing inside the distributor cap, as the contacts are too close too each
> other at those voltages, with a little arc dust build-up inside the cap.
Ford
> didn't add cost to make it pretty.
A HE ignition system will still only generate as much voltage as is required
to bridge the spark plug gap, plus the cap-rotor gap. If this voltage
exceeds the voltage required to arc over to another terminal then you get
crossfiring.
<snip>
> There is a wick, underneath the rotor, that requires periodic oiling.
The wick only lubricates the mechanical advance shaft (with the cam/reluctor
on it). If you oil the heck out of this it will eventually seep to the
bottom of the cam/reluctor stub shaft and then get flung off by the
mechanical advance plate. Then if enough collects there, it will flow out of
the vent hole in the bottom of the distributor.
<snip>
> The 16 and 20 limit plates are for mechanical advance distributors. The
vacuum
> advance units are generally stamped 10 (dist. degrees). I use a 10
distributor
> degree (stock) limit plate on the mechanical advance, 10 degree
(distributor)
<snip>
The 16/21 plate came out of a vacuum+mechanical distributor, on an automatic
transmission installation ('78 mustang II). The parts counter person I got
the new vacuum diaphragm from had different listings for manual vs.
automatic transmissions, so I got the manual trans version. The two other
plates had two different sets of advance limits (one was 13/10, I believe,
and I don't remember the third). These are not usable by me because they
won't accept the reluctor.
> I hope this individual experience helps, although there are those with the
> actual system you are considering, like Bob Palmer, who have "hands-on"
> experience. And Bob is futzing with changing his already large gap about
0.05,
> so he must be as much into precise optimization as anyone. He may even
have
> indexed his ignition key, as well - so don't bet on a drag race with him.
{9->
Thanks,
Theo
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