What are points?!?
Sean Bacon
working on cars, I have never worked on points in a car. So my question is:
What are points and how do they work. Also, how do you know if your points
are bad?
Thanks for any help.
**************************************************************
* Sean Bacon Test Engineer *
* Delco Electronics *
* "Not even the rain has such small hands." E. E. Cummings *
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Wes Fujii
: I am a fairly young guy, and although I have had some limited experience
: What are points and how do they work. Also, how do you know if your points
: are bad?
Well, unless you're gonna own or work on some pretty old cars, you don't
need to know what points are:
Points are the electro-mechanical switches that are used to charge the
primary side of the coil for your ignition. Located between the coil and
ground, it (they) open and close, following a lobed distributor shaft
driven by the camshaft. When the circuit is closed, the current flows
through the coil to ground and creates a magnetic field within the coil.
When the points open, the magnetic field collapses and the rapid collapse
of the magnetic field is picked up by the secondary wiring in the coil
and creates the high voltage that travels out the distributor and to each
spark plug. The spark at the plug ignites the fuel mixture in the cylinder.
There are two wear sources for points. The block that follows the
distributor shaft cam can wear in time, even though it is lubricated with
a grease. The electrical contacts themselves can erode because of the
constant mini-sparking that goes on with every ignition cycle. When either
the cam follower block or the point contacts erode, the EXACT timing of the
spark pulse will change. If things get too far out of whack, the engine
will run very poorly or not at all. Tune-ups on a point-equipped vehicle
are necessary often. I seem to remember doing mine yearly. Tune-ups
involve cleaning and accurately setting the gap spacing between the points
at maximum spacing (which in turn sets the amount of time that the primary
side of the coil charges the magnetic field), and adjusting the distributor
for the optimum spark timing.
Electronic ignition has replaced points and their associated problems
very effectively.
Wes Fujii
________________________________________________________________
___ ___ ___
/ / / // /
/ /__/ // / A real motor is an Oldsmobile Rocket 455
/ HURST // / "This is NOT the new generation of Olds"
/ / / // /_______
/__/ /__// // ___ \
/ // / \ \ Wes "BANZAI" Fujii
/ // /OLDS/ / Boise, Idaho
/ / \ \___/ / we...@hpdmd48.boi.hp.com
/__/ \_______/
Greg Beaulieu
: I am a fairly young guy, and although I have had some limited experience
: Thanks for any help.
Sean, where do you work again? Delco? Check out back... I bet there's a
warehouse FULL of breaker points.
Points are spring-loaded contacts that are allowed to open and close by
the rotation of a cam inside the distributor. By doing so, they allow the
hi-tension (spark) circuit to cycle on and off, thereby causing a spark
at the spark plug. If they are misadjusted or worn, the engine will not
perform properly and will generally have either a misfire, rough idle,
low power, etc. In modern cars they have been replaced by electronic
ignitions (also made by your company) where the circuit is opened and
closed by either light or magnetic impulses.
If you DO find a warehouse full of Delco Uniset point/condenser sets, give
me a call. I can use them for my '68 Olds and "64 Buick....
(Apologies for having a little fun with you and your employer....)
Greg.
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