1964-1974 [Subscribe to Daily Digest] |
[Profile/Gallery]
, Sun, 8 Apr 2001 18:34:18
Members do not see ads below this line. - Help Keep This Site Online - Signup
You're not an idiot, you're just too young to have had to deal with this before! Points about points:
-- The points are a mechanical switch that turns on and off the 12v power to the low-voltage side of the coil. The coil is actually a transformer, and this on-and-off action allows it to step up the voltage to several thousand volts, which is sent through the spark plugs to make sparks.
-- The points live inside the distributor, and you can see them by removing the distributor cap and rotor. You'll see a metal frame that holds the fixed point and the movable point, which is spring-loaded and can be moved back and forth on a pivot. A piece of plastic (the rubbing block) on the movable point presses against a square cam on the distributor shaft. It's the rotation of this cam that moves the movable point and makes the "switch" turn on and off.
-- Connected by a wire to the points and mounted on the outside of the distributor housing, you'll see the condenser (in electronics, this is usually called a capacitor.) It works like an electrical "shock absorber" to make the points last longer. Usually when you do a simple electrical tune-up, you'll replace both the points and the condenser.
-- The important setting for the points is the "dwell angle," the angle (of distributor rotation) through which they remain closed. If they stay closed either too long or not long enough, the coil can't build up enough energy to make an efficient spark. You change the dwell angle by moving the fixed point so it's either closer to or farther from the movable point -- closer makes the points stay closed longer, farther keeps them closed for a shorter time.
-- You adjust the points by loosening the shiny screw in the base of their bracket, which lets you move the bracket so that the fixed point moves in or out. (Just loosen the screw enough to let you move the base -- a little friction helps it hold the settings.) To make this easier, there's a little notch on the end of the bracket into which you can put a screwdriver blade and twist it to slide the bracket in and out. Once you're done, be sure to re-tighten the screw.
-- You can get the correct setting one of two ways: buy a "dwell meter" which measures the dwell angle directly via an electrical connection; or use a flat feeler gauge to set the correct gap between the points when they're open all the way (when the rubbing block is on one of the high spots of the distributor cam.) The dwell meter is more accurate, but costs more to buy. Different engine types and years may have slightly different dwell/gap settings, so you have to check the specs in a manual for your particular car.
-- Changing the point setting can slightly alter ignition timing, so be sure to re-check that after you've set the points.
Sound like a lot of bother? It is -- which is why V4 owners who don't insist on keeping the car original (such as me) often invest $90 or so in a gizmo called a Pertronix Ignitor, which replaces the points set with a magnetic trigger like the ones used on modern electronic ignition systems. Since the trigger doesn't wear the way points do, there's no point gap to adjust and your ignition timing doesn't need to be re-checked as often. The Ignitor fits completely inside the distributor cap, and installing it is easier than putting in a new set of points. Marque specialists such as West of Sweden Saab (see classifieds page) can sell you one.
If your Sonett has a two-stroke engine, (a) you're a lucky devil and (b) you probably should stick with the regular points set, since getting an Ignitor to work with a 3-cyl. engine requires a bunch of special adaptations.
, Sun, 8 Apr 2001 18:34:18
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
