It seems that there are two dwell angles for 4-cyl. cars. ca. 60 degrees
and ca. 52 degrees. 60 degrees is used most on EU cars with high lift
cams in the distributor (whatever that means). On the Lucas 23/25D4 (on
my cars) and 43/45D4 distributors it is 60 degrees.
Just as well David does not always agree with me. I do not pretend to be
always right. I am only human. However there is often room for
discussion and the truth can be both ways.
Cheers,
Kees Oudesluijs
David Porter schreef op 24-10-2014 15:07:
> 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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