Cam Angle Degrees = Dwell?

[keithb7]

I was looking up the points gap specs in my 1938 P6. The original setting in the shop manual is 0.020" with a feeler gauge. This is the stock 201 engine. 

I referenced my same era Motors Manual. It also reads "Breaker Gap .020". The motors manual also lists, right beside breaker gap, "Cam Angle Degrees 38".

Is that 38 degrees a dwell setting?

 

Then I remembered that my 1938 has a 1954 year Canadian 226 ci engine in it. I went to my 1954 shop manual. It lists 38 degree dwell. 

I have a dwell meter. My current dwell measures 22 degrees. So tomorrow I will re-set it, and re-set the distributer timing too.

 

Then I got wondering,  is the "Cam Angle Degrees 38" in 1938, also the Dwell?  Am I right to assume that electric Dwell Meters were not in use yet in 1938?

I'm guessing a mechanic in 1938 could measure the distributor cam rotation somehow while points are closed? 38 degrees. Maybe using a dial indicator? Inserted down the access hole in 

the head at cylinder 6?

[Plymouthy Adams]

yes...and anytime you are tweaking used points the dwell is the best way to establish the gap as the feller gauge cannot set used surfaces with accuracy.  The Cam Angle is just another term to express the time the points stay closed to saturate the coil.  It is in truth the duty cycle.

[T120]

This is a meter that I still use. I bought it at a farm auction some years ago, cost was $7.00...

Edited July 7, 2020 by T120

[keithb7]

@T120 When you are ready to sell that, let me know! My dwell meter has a tach but only works with 12V.

My dwell works fine. I need a 6V model to get engine RPM readings.

[busycoupe]

Try your meter on 6 volts. Just be careful to get the polarity correct.  It will probably work fine on 6volts, my  70's vintage Sears meter does even though it is labelled for 12 V neg ground.

[TodFitch]

1 hour ago, busycoupe said:

Try your meter on 6 volts. Just be careful to get the polarity correct.  It will probably work fine on 6volts, my  70's vintage Sears meter does even though it is labelled for 12 V neg ground.

 

My generic tach/dwell meter acquired from a local auto supply about 10 years ago works just fine for both tach and dwell on my 6v+ Plymouth. Remember they are designed to clip on to the wire going to the points and even on a 12v car, the voltage to the points was close to 6v, dropped from 12v by either an external ballast resistor or a ballast resister built into the coil.

 

And yes, be sure to get the polarity correct. I would hope the device would be protected against ham fisted mechanics clipping the leads backwards but you never know, so just to be safe double check before you clip the leads on.