Dan
Here are the numbers I found.
Points gap = .019" - .021"
Dwell = 30 - 33 deg - for both points
26 - 28.5 deg - for each set
When you measure dwell you will see both sets of points unless you
tape over or isolate one set of points at a time to make a dwell reading.
Any one points gap will support only one dwell angle, say .016" = 27
deg dwell. The only way to change the dwell of a single point set up is to
change the point gap.
Dwell gives the coil time to build energy, more time = more energy,
but you also need time for all that energy to be sent to the spark plug, so
you don't want to large of a points gap. As you run an engine at higher
RPM lower points gap are needed because the cycle time for the coil gets
smaller and it needs more dwell time to deliver a good spark. At 6000 RPM
the coil is firing 400 times/sec, the coil cycle time = .0025 sec.
Dual points allows 2 sets of points set at the same gap to give you
a larger dwell angle up to 8 deg, which gives the coil a little more time to
build energy and deliver a good spark.
Dual points are mainly used in racing where the engine is running
high RPM's and the total number of degrees advance must be limited to around
34 degs. A single point distributor with vacuum advance can deliver 50 deg
advance but only at low RPM's. It all boils down to economy vs
performance.
Ron Fraser
-----Original Message-----
From: owner-tigers@autox.team.net [mailto:owner-tigers@autox.team.net] On
Behalf Of Dan & Lori Fitzgerald
Sent: Wednesday, May 28, 2003 2:06 PM
To: Tigers@Autox. Team. Net
Subject: Dual point Distributors
Listers,
I have a question concerning dual point distributors. What should the point
gap be at? If I measure the dwell, won't I see both points, how can you
tell which point needs to be adjusted? Can some one explain to me what the
added point set does in the ignition circuit?
Thanks,
Dan
B9470033
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