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Re: Coil confusion

To: "DASHWOOD, Dean, FM" <Dean.Dashwood@rbos.com>,
Subject: Re: Coil confusion
From: Douglas Braun <doug@dougbraun.com>
Date: Wed, 17 Dec 2003 10:18:38 -0500
Pretty much any coil meant for a 4-cylinder engine with a 12-volt system should
be electrically compatible with your car.  Think about it:  what makes your 
car's
ignition system different, electrically speaking, from any other 4-cylinder 
12-volt car?

The electronic ignition, from the coil's point of view, is not much different 
than
a point ignition:  it basically switches the current to the coil on and off.
(This is assuming that the electronic ignition is not a "fancy" type,
like CD or MSD.)

Most of the differences between those 20 coils in the catalog are mechanical:
the size and shape of the coil itself, and the type of terminals for the wiring.
Presumably some are meant for 8 vs. 6. vs. 4 cylinder engines, since
a 8-cylinder car fires its coil at twice the rate as a 4-cylinder car.

BTW, a coil gets relatively hot at idle, since the power drawn by the coil 
between
sparks is turned into heat instead of sparks.
If your coil is too hot, one possible cause is the dwell angle being too big, 
but
this is usually not adjustable on electronic ignitions.  Smart electronic 
ignitions
will reduce the dwell angle it idle to avoid wasting power and overheating the 
coil.

Doug Braun
'72 Spit


At 09:00 AM 12/17/2003 +0000, DASHWOOD, Dean, FM wrote:
>Listers,
> 
>I need some help understanding which coil I should have on my car.  The car
>is a Spitfire 1500, but at some point in its history it's been fitted with
>an electric (optical type) ignition system.




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