<VV> What is Dwell?

[Greg Blakeney]

Most informative synopsis. Last year my points all but closed up. Very little opening at the peak, Happened gradually over several hundred miles of driving. Aside of the 'miss' I was hearing more and more of, it got progressively harder to start as the last line of this message says. 

Thanks!

gerg•A•licius
All Air-Cooled


> On Sep 23, 2014, at 12:59 PM, Smitty via VirtualVairs <virtualvairs at corvair.org> wrote:
> 
> Smitty says;  As a straightforward answer to Jeff's straightforward question, can you have too much dwell.  Yes you can.
> I offer this short tutorial.  When a coil such as the one in your ignition receives a charge of DC the, coil absorbs the charge and being a transformer, kicks the voltage way up in the secondary windings.  (The ones feeding your plugs).  The coil reaches a point of saturation but immediately the voltage starts to decay.  It can not be maintained by DC.
> The engineers have calculated how long it takes,from when the points close, for the charge to build up to that peak.  Then they design the distributor make the points snap open which releases the built up charge from the coil. If the points stay closed too long the decay will take place too long and the stored voltage will drop off to nothing.  That "charge up"time is called dwell.  (The period of time the points dwell together).
> The engineers had to make an educated guess on how much dwell to set up when adjusting the points to satisfy the needs of the engine from 500 rpm to 7,000 rpm.  Obviously there isn't much dwell at high RPM and way too much at Idle, so they made a best guess and gave it a number.  First indication of too much dwell ( points too close ) is hard starting. 
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