Phil....
Tegler's site also gives the serial number
(in reallity, the advance curve) and whether
the vacuum is of the advance or retard type,
the former used on pre-emissions and
post-emissions cars (carb. ported) the later (intake manifold ported) used on
emisson type engines only, as far as I know.
Type "A"..
The vacuum advance type is ported to the
carb, and advances under light throttle
(high vac) conditions. As manifold vac.
drops (your foot goes down), vac. advance
becomes less until you are left with mech.
advance only. Dynamic timing is set with the vac. advance disconnected.
Type "B"..
The manifold ported types are basically
retard types, wherein full vac. advance is
obtained at idle. As your foot goes down,
this advance retards and you are left with
mech. advance only. Dynamic advance is
set with the vac. advance connected.
Were you to hook up the Type A to the
intake manifold, you'd get full vac advance
at idle. Assuming you set the timing with
the vac. line connected, it would run great
until you put your foot in it. At this point
the motor would go flat as the mechanical
curve would be running greatly retarded.
If you set the timing on the foregoing with
the vac. line dis-connected, all would be
well until you hooked up the vac. line
wherein the motor would be so advanced
at idle, I doubt the motor would
turn over without backfiring in an attempt
to run the wrong way. If it did start, it would tend to run very overadvanced
at less than relatively full throttle.
You can figure out the other one for your
self.
But the point is, match the serial number of your distributor with the
information contained on Tegler's site to know what you have and to get it's
hookup operationally correct.
Do not confuse emissions ports on carbs
with vac. ports on carbs as both are, as I understand it, "graduated orifices"
(specifically sized ports for a specific use).
I use a special Aldon 43D mech adv.
only distributor however,
my stock 1.25 SU set-up has a tiny barb on the front of the front carb. for the
dist.
vacuum line. It is ported to the carb side
of the butterfly for the motor's normally stock 24D mech/vac. advance stock
dizzy.
Don't recall which carb has this barb is specifically on the larger twin
set-ups.
Cap'n Bob
Basic Frog
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