"Is there a resource....."
Sure, Larry....a dyno.
Read the appropriate chapters of Dave
Vizard's book on Series A motors and it
will explain all.
But the fact is, the engine will run pretty
well with a variety of advance curves available for the Series A, as
produced
by the factory. It just may not run at it's
very best.
Paul Tegler's website lists the dizzy's along with curve information:
www.teglerizer.com
For a normal street machine....you can
put the "curve" for a 948 in a 1275. It will
run fine. And vice versa. Sure, for any
given mixture curve (needle in the case
of SU(s)) it may be a little lean or a little
rich here and there, but it'll run. I mean,
how much time will a street engine be
driven at WOT?
So a little leaness or richness here or
there isn't going to be a big deal unless
you are continually "driving like you stole
it" or racing it. Then you better get it
more or less right...the advance
curve for the mixture curve. In the first
case you'll get less performance and
economy then you could were the
curves "more right", and in the second you
won't win any races. In both cases you
may get less engine life.
Something that can give us CO along
hp generated at the flywheel or driven
tires is the way to go...engine or chassis dyno, respectively. A mixture
ratio
of 12.5-1 for WOT acceleration and
14-15 to 1 for "cruise" at any given rpm
and any given Series A will give me it's
best and last the longest doing it.
This is what is meant by "dialing in" an
engine on a dyno.
The "good" dyno operator must know
how to run a dyno AND be an engine
tuner as well....he's gotta be both to get
the job done right.
I had one guy who couldn't figure out why
the motor was "drying out" at the top end,
though we had a main jet that was sufficient to produce good low and
mid-range max hp for any given rpm
(torque). In this case, I knew combustion
characteristics and he knew how to run
the dyno! Answer was simple (to me)....
to much advance at the top.
We pulled the dizzy and lopped off a couple of degrees to give us a max
of
28 degrees instead of 32. Bought the
top end CO right into the ballpark. Prior
to this, we had incrementally increased
the size of the main jet until it began to
run "soggy" at the bottom and towards
the middle. Backed off to get this "right"
and went up .05 on the pump jet (45
DCOE) to give a little extra fuel at the
top. Still "too lean" up there so, had to
be too much timing.
Bear in mind that we started out with
"known" correct carb settings and ignition
curve settings for the stock motor and
were tuning for a "hot street" tune...this
makes it much easier. It wasn't as though
we were starting out with nothing and had
to put it all together!! :):)
Cap'n. Bob
'60 :{)
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