Magneto Timing

RUSHTON · Post by **RUSHTON** » Thu Mar 31, 2011 4:02 pm

41 G3L
I am timimng up the magneto and have a question : does the spark occur when the points are opened, or when they close?
I have followed the manual to the letter and set the points, testing them with a strip of paper to check the release, but can't work out when the mag charges up; points closed or open?
R

chasdev · Post by **chasdev** » Thu Mar 31, 2011 4:06 pm

The spark occurs just as the points open.

Don Madden · Post by **Don Madden** » Thu Mar 31, 2011 5:44 pm

As Chas says, & the mag is charging just before the points open with the current shorted by the points until then. Cheers, Don.

Rob Harknett · Post by **Rob Harknett** » Thu Mar 31, 2011 5:51 pm

Dont overlook the advance / retard lever should be set in the fully advanced possition when doing the timing.

chasdev · Post by **chasdev** » Thu Mar 31, 2011 7:48 pm

AND for anyone intererested, the reason the point gap is important is that it alters/controls the amount of time the points are closed, during which time the charge builds up, ready for the next discharge.

Wolseley1800 · Post by **Wolseley1800** » Thu Mar 31, 2011 10:30 pm

AND for anyone intererested, the reason the point gap is important is that it alters/controls the amount of time the points are closed, during which time the charge builds up, ready for the next discharge.

Commonly known as the 'Dwell Angle'

chasdev · Post by **chasdev** » Thu Mar 31, 2011 10:32 pm

That brings up a question that I've been meaning to ask, will my dwell meter function on a magneto system and if so what number should I look for, 30 degrees?

RUSHTON · Post by **RUSHTON** » Fri Apr 01, 2011 10:11 am

Thanks fellas.
I followed the manual but suddenly had a moment of doubt.....R

aobp11 · Post by **aobp11** » Fri Apr 01, 2011 12:45 pm

Chas, no, probably your meter will consider 0 V as closed and +12 V as open and switch somewhere between these voltages. The open magneto voltage behaves completely differently. Also, the contact angle itself is less important for a magneto system. Most important are the pole positions when the points open. For an N1, with slotted breaker plate position, this is only influenced by the points gap and by advanced/retard. With too large gap and fully advanced the spark quality might degrade.
Finally the gap determines the speed at which the points open. Too slow will produce heavier arcing between the points. The prescribed gap is probably the best in this respect.
Albert