One of the problems with the stock distributor is that the shaft
bent and this leads to an alternate point gap for opposite cylinders.
Checking you will see that the static timing for example the
cylinder is perhaps 10 degrees, but when you turn the engine
over to the
number four cylinder the timing is as much as 2 or 3 degrees
less or MORE.
Therefore you have an engine that is operating with either too
on alternate cylinder or not enough. In the end you find that
have programmed only 30 degrees of total timing into the engine
you are in
fact carrying 32 degrees or more on other cylinders, and those
then are more prone to detonation.
In the end the check for detonation is the window to the combustion
the spark plug. Install clean (not necessarily new) plugs or
even a couple
cleaned plugs and run a lap or test length, pull the plugs and
carbon specks and worse yet is tiny aluminum balls. If you find
aluminum balls on the center insulator of the spark plug, unless
immediately do something about the timing the piston in that
cylinder is not
long for this world. If you are doing this check on a race track
filters, do not confuse the tiny BLACK shiny balls for aluminum.
black balls are RUBBER. They don't appear black until you look
and are easily confused in appearance with aluminum which are
Basically the early Lucas units, up to the late 60s, had a symetrical
lobe & a tendency to bounce the points at medium-high rpm,
with the standard
points. There are/were different points available with more spring
you can add a spring strip, to raise the limit using this unit.
assymetrical lobe design has a ramp that opens them quicker & increases
saturation time, allowing a more reliable spark at high speed.
came out with the 45D unit which was designed for the HEI system.
It has the
larger body, cap & rotor, & the cap has walls inside,
all designed to prevent
spark-scatter from the HEI.
A point type distributor based on the 45D body, assymetrical
points with a locked braker plate, is good for over 7000 rpm
in a 4 cylinder,
reliably. (example- my girlfriends POS 1275 Sprite will pull
reliably to 8k). For
max reliability or regular use over 7000, I normally will fit
trigger unit such as Allison or Lumenition.
6 cylinder engines are a different story since the saturation
obviously decreased by having 6 impulses per distributor rev
vs 4. Dual point
systems were really designed for 8 cylinder engines, where there
minimal saturation time.
It goes without saying that the distributor has to be in good shape re
shaft, bushings, breaker plate, etc & a critical point is the indexing of
breaker plate to the body. If it's not locked in the correct orientation, the
rotor tip won't line up with the contact in the cap. You can see where the
spark is going by looking at the carbon track on the tip of the rotor.
Well, it looks like you absolutely know how to make a lucas
work. My tolerance is far less than yours.
The distributor I tried to use is the 45D. What finally put
me over the edge
is the realization that in this "racing" distributor
the point plate is the
same as the vaccum advance unit and is "fixed" in place
with a tab that lets
it shake about two degrees. Yes, I could fix that, and I could
properly index the distributor with a distributor machine, or
I could buy a
Mallory and start building a catapult.
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