17-03-2025, 12:40 PM
(16-03-2025, 08:40 PM)John Cornforth Wrote: Hi Ray
It's always difficult to ascertain someone's electrical knowledge, but as you are getting odd results here's how I would test things.
Set the test meter to a DC voltage range that can measure 6 volts
Connect the black meter probe to battery negative (negative earth assumed) ideally with a hands free clip of some sort, and leave it there.
Remove the distributor cap and rotate the engine till the points are open
Turn on the ignition, and using the red meter probe measure the DC voltage at the coil switched supply terminal, the coil contact breaker terminal, the terminal on the side of the distributor, the distributor metal body and the engine block. Note down these five voltage readings which I will call A,B,C,D, and E
Now rotate the engine till the points are closed, and repeat the above test noting down the five new voltage readings which I will call F, G, H, I and J
Turn off the ignition
The readings I would expect to see are:
A 6.5 Volts. ------------------5.97
B 6.5 Volts ------------------5.97
C 6.5 Volts. ------------------5.98
D 0.0 Volts. ------------------0.00
E 0.0 Volts. ------------------0.00
F 6.0 Volts. ------------------5.29
G 0.5 Volts or less ----------0.17
H 0.5 Volts or less ----------0.15
I 0.2 Volts or less -----------0.07
J 0.0 Volts. ------------------0.00
There may be some minor variation, but nothing too far adrift from those values. Let us know the results !
P.S. The technique works for positive earth, but the meter will register negative voltages which is not a problem for a modern digital meter. If using a moving pointer style meter, swap red and black leads.
The battery is now on charge.