> When setting the dizzy point gap, the rotor turns in a clockwise
> direction.> Does that mean that by rotating the dizzy in an
anti-clockwise
> direction, I am advancing the spark?
Yes. Because you are turning the distributor opposite to the normal
rotation of the rotor, you are advancing the spark. The rotor is linked
to the engine--it's not adjustable w/o taking things apart. That's not
part of this operation.
>
> > That causes the spark to happen earlier in the piston movement.
> To retard the spark, we turn the distributor in the same direction as
rotor is turning, which means that the spark will take place later in
the piston movement.
>
> So, if by turning the dizzy clockwise I'm retarding the spark, it
> then means that I have a retarded setting, which by eye, looks to be 20
deg.
> The motor runs far, far better at the retarded setting. Starts first
kick w/o
> choke) & doesn't run on.
>
Yeah, sort of. You are using the timing light?
Now there is another variable that we have not discussed heretofore. The
front pulley may have a rubber piece in it, that is (or was) bonded to
the inner part and the outer (grooved) part of the pulley. It's not
unknown for this bond to separate and for the outer part to rotate
somewhat around the inner part (hub) If that happens, the calibrations
for TDC goes off. It doesn't affect the internal workings of the engine,
but it will certainly confuse the person using a timing light. From what
you have said, though, I don't think you have this problem. Even if you
do, it's not insurmountable.
The advance mechanism alters the advance to fit the needs of the
engine at various RPM. At starting, maybe 300 rpm, it does not need or
want much advance. Chances are that the advance at that point is 5 or 6
degrees. As the RPM increase, the spark must be sparked earlier
("advanced") relative to the position of the rising piston. The little
flyweights in the distributor do that automatically. I must confess to
being old enough to have driven a Bugatti in which spark and mixture were
adjusted by the driver with levers from the dashboard. But for MGBs, if
you get the spark sparking at 18 degrees BTDC, w/o any vacuum, at 1500
rpm, you are in the ballpark for good setting adjustment. You can tweak
it from there.
> Is that right? If that is the case, what other adjustments need to
> be done, in order for the spark to be in the advanced range and give
the
> performance I know have. Also what are the consequences of running at
such a
> high retarded setting.
If it's really retarded, you will find that it has less power than
your lawnmower. It may start promplty, but will run like a broken-leg
dog. And the temp gauge will be higher than you are accustomed to.
Bob
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