Steve,
The spark sparks at different points in the engine cycle depending on
the engine rpm. The purpose of the advance weights in the distributor is
to "advance" the spark (making it earlier, more before Top Dead Center)
as the engine speed is increased, to a limit of about 32 degrees. What
should happen is that the vacuum advance and the centrifugal (weights)
advance work together to move the timing around to best meet the engine's
needs at any given speed and load (hills / flatland, accellerating /
coasting) etc.
These distributors are not precision instruments, they're 30+ years
old, fuels have changed and other variables are now in the picture. As
Paul pointed out, one determines the optimum setting for a given engine
by experimentation. There may be no perfect setting.
But if your engine isn't revving above 3000, something is quite
abnormal. It should rev easily to 5000 or more. To the task---
The engine turns clockwise as you look at the pulley. The notch on
the pulley represents Top Dead Center. The large timing pointer is 0;
each of the little ones represents 5 degrees advance. At the prescribed
speed ( 1500 rpm or so ) with the vacuum advance line disconnected and
plugged so air is not sucked into the engine, set timing to the
prescribed advance (14, 15, 16, whatever ) with the pulley notch aligned
with the pointer, snug the bolts and reconnect the vacuum line.
Then when you then shine the timing light on the marks as someone
revs the engine, you should see the timing advance, then retard as engine
slows. If that does not happen, the advance mechanism is not working
properly. If that advance and retard does not take place, write back.
Another way to do this timing is suggested by John Twist, which is to
make a mark for 32 degrees, then set the timing at 3000 rpm. Those who
are not comfortable with their faces close to spinning fan will prefer
the 1500 rpm method. They both work.
Bob
On Sun, 3 Aug 2008 11:42:15 EDT Daybell7@aol.com writes:
> MG'ers,
>
> I don't understand where or how my timing should read for peak
> performance.
>
> While standing on the right side of the car with a timing light,
> should the notch on the crankshaft pulley read lower (closer to me)
than the
> timing marks at 14 degrees BTDC?
>
> How can I maximize performance by adjusting the timing? I have an
> electronic ignition. The car doesn't run bad, but won't achieve
> high rpm (say 3000). Is this normal?
>
> Thanks in advance.
>
> Steve Hughes
> Gainesville, FL
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