Well, the 'solution' is obvious: you just have to measure dwell at specific
lift, like camshafts (usually 0.050" lift).
Half kidding.
Bob
----- Original Message -----
oh geeze.. hope this doesn't turn into a 'what oil' or 'what tires'
thing.. anyway it has made me think and start reading (easy with
computers these days). problem is separating machinist think from
mechanic think, I think. ;~)
Any way here is a short explanation for all of us directly from the
Internet I found this morning:
When the distributor shaft is rotating, the contact-breaker points open
as the heel of the moving point is pushed outwards by a lobe of the cam,
and close while it is over the flat area between two lobes.
If, for example, the angle of rotation between the centres of the lobes
on the cam is 90 degrees, the dwell angle - the period with the arm over
the flats and the points closed - may be 52 degrees; the remaining 38
degrees are taken up by the action of opening and closing. This would be
a typical dwell angle for a four-cylinder engine
<http://www.howacarworks.com/basics/the-engine>.
A dwell meter connected between the distributor or ignition coil and
earth registers the dwell angle on a scale, and must remain steady at
the prescribed figure while the engine is running. If the dwell angle is
not the same for all cylinders, the result is rough running and poor
fuel economy because the moment the spark-plug fires varies from
cylinder to cylinder.
The dwell angle varies according to the make of car; check it in a
service manual. There are two scales on the meter, one for four-cylinder
engines and one for six-cylinder engines. Eight-cylinder vehicles are
taken from the four-cylinder scale and halved.
End of article... I liked this one best as they use the numbers I
posted yesterday that let me validate (personally) that I haven't
completely lost my mind yet..:-)
BTY, I don't ever disagree with Michael or Richard, Kees sometimes..
dp
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