Understanding Breaker Point Ignition Systems
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Starting at the battery cables go around the circuit testing each wire and connection. Block the points open and place each probe on one of the points. If the light goes on you have found the problem. Look carefully to find the bare patch of insulation or missing rubber washer on the distributor wire.
With the points touching and the probes on each point the light should shine for you. If the light doesn't go on they aren't really touching or they are so corroded that they won't conduct electricity. You can file them down, or better yet replace them. It is a good idea to replace the point condenser at the same time. The condenser is usually located inside the distributor, but sometimes is attached to the outside housing. It has a single lead that attaches to the points where the negative wire from the ignition coil attaches.
If you're still not having any luck, try checking the resistance of the spark plug wires. I know a lot of us hate manuals, but it's good to have the specs for your piece of iron so you can test these things out. Any spark plugs wires with cracked insulation should be replaced.
Use your multi-meter to test the spark plugs. There should be continuity between the top of the plug and the electrode. There shouldn't be any continuity between the screw threads and the electrode. Put the end of the plug in the boot on the end of the ignition wire and test for continuity between the electrode and the end of the plug wire. This will rule out a bad plug wire or a bad connection between plug and wire.
If you have gone through all of this and still can't get any spark take a look at the cap and rotor. These are usually the first parts that get replaced when someone is going over the ignition system. If they look old or damaged, I would replace them.
After going through all of this you should have a good feel for how your breaker point ignition system works, and how to work your way through when you're having ignition-related problems. Understanding how the system works is key, and if you take your time and trace the system down, you'll always find your way to making it work.
Contact engine enthusiast Gary Grinnell at: 9 Laurel Park, Northampton, MA 01060-1196.
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