While a dwell/tach is great for setting the idle speed, for the ignition
systems still using breaker points you can use the dwell meter to set the
dwell of the points as well.

When performing my regular tune-ups I always start by checking the dwell and
adjusting the points as necessary.  If you need to adjust the points
frequently then you may need to lube the block on the points and or check
the cam on the rotor shaft.  After the dwell then you can set the idle and
timing.  The whole process should only take a few minutes once you get it
down, and all of the numbers are in the engine compartment on the tag above
the coil (at least for the early vanagons).  I find that setting the point
gap with only a feeler guage often yields improper dwell settings which as I
understand it are all that matter.

Some of the experts can shed light on what I have written as it is based on
my isolated experience.

Jonathan Poole