Measuring dwell angle
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In the recent thread regarding webber tuning it was suggested that the
dwell angle was checked. I can't say I have ever 'measured' this. I have
always just set the points gap using feeler gauges. Knowing how 'hit and
miss' this can be especially if trying to do it with the carbs in place I
thought it would be worth trying to measure the actual angle whilst the
engine is running. Can it be measured using a conventional multimeter or do
you have to have one of those special dwell meters? I would guess that by
measuring the volts at the points with the engine running, a certain
percentage of battery voltage would be equivalent to a certain dwell angle.
Has any one done this? Would you set the meter to measure AC or DC? Is
dwell angle simply the ratio of points open to points closed i.e. an angle
of 60 = points open for 40% and closed for 60% of the total time.
Thanks for any info.
Keith Scarfe.
dwell angle was checked. I can't say I have ever 'measured' this. I have
always just set the points gap using feeler gauges. Knowing how 'hit and
miss' this can be especially if trying to do it with the carbs in place I
thought it would be worth trying to measure the actual angle whilst the
engine is running. Can it be measured using a conventional multimeter or do
you have to have one of those special dwell meters? I would guess that by
measuring the volts at the points with the engine running, a certain
percentage of battery voltage would be equivalent to a certain dwell angle.
Has any one done this? Would you set the meter to measure AC or DC? Is
dwell angle simply the ratio of points open to points closed i.e. an angle
of 60 = points open for 40% and closed for 60% of the total time.
Thanks for any info.
Keith Scarfe.
- Keith Scarfe
- Third Gear
- Posts: 287
- Joined: 10 May 2004
Keith
I went the easy way and used a dwell meter. They are not too expensive and
usually have a tach setting as well. This is a lot easier to do than to
hang a mirror on the steering wheel so that the cockpit tach can be watched
while tuning the carbs!! (This is a suggestion in the workshop manual.)
In the US most dwell/tachs have an 8 cyl and a 6 cyl scale. For a 4 cyl you
double the reading on the 8 cyl scale.
Don
I went the easy way and used a dwell meter. They are not too expensive and
usually have a tach setting as well. This is a lot easier to do than to
hang a mirror on the steering wheel so that the cockpit tach can be watched
while tuning the carbs!! (This is a suggestion in the workshop manual.)
In the US most dwell/tachs have an 8 cyl and a 6 cyl scale. For a 4 cyl you
double the reading on the 8 cyl scale.
Don
- donselan
- Second Gear
- Posts: 143
- Joined: 30 Nov 2003
Dwell becomes important when adjusting used points that are servicable,
but have depression of mating contact in face. Feeler gauge will give
too wide an actual gap, too little dwell, and not enough time for optimal
magnetic field at higher RPM's, resulting in lower coil output.
Theoretically, you could use a voltmeter, I have never opened my dwell
meter up(if it ain't broke don't fix it), but know it works equally well
on 6volt, 12 volt and 24 volt ignition systems. George
On Mon, 18 Sep 2000 11:10:11 +0200 ***@***.***es:
but have depression of mating contact in face. Feeler gauge will give
too wide an actual gap, too little dwell, and not enough time for optimal
magnetic field at higher RPM's, resulting in lower coil output.
Theoretically, you could use a voltmeter, I have never opened my dwell
meter up(if it ain't broke don't fix it), but know it works equally well
on 6volt, 12 volt and 24 volt ignition systems. George
On Mon, 18 Sep 2000 11:10:11 +0200 ***@***.***es:
- gobw2
- Fourth Gear
- Posts: 975
- Joined: 25 Sep 2003
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