An ice pick style test light is your best friend when diagnosing ignition problems. Find a good ground, attach the wire clip to it, and TEST THE TEST LIGHT! Find a known source of voltage like the battery cable connection at the starter, for instance, and make sure the test light bulb isn't burned out. Now, start checking the primary ignition circuit. Turn the ignition switch on and check the following connections- - - -in order:
1. Coil + terminal- - - -the one coming from the ignition switch. You should get a good bright light anytime the ignition is turned on. If the light is dim or not on at all, go under the dash and check the back of the ignition switch for loose or dirty connections. If the Light is good at the coil +, go to the other terminal.
2. Light on at the distributor side of the coil- - - -this can be good or bad, depending on the position of the points. Remove the distributor cap. If the points are open, the light at the (-) coil terminal should be on. Turn the engine until the points close- - - -the light should go out. If it doesn't, check the terminal at the side of the distributor. If the light is on there with the points closed, clean or change the points. THIS IS THE MOST COMMON CAUSE OF A "NO SPARK" CONDITION- - - - -BURNED OR DIRTY POINTS! A failed condenser is a possibility, but it's pretty remote.
3. If the light flickers on and off at the coil (-) and/or the distributor side terminal as the engine is cranked, you have a good primary circuit. Now check the secondary (high voltage) circuit. Remove the coil wire from the center of the distributor cap and hold it within about 1/4" of the engine block or cylinder head while someone else steps on the starter pedal. If you're by yourself, open and close the points with something non-conducting like a popsicle stick, a plastic spoon, etc. The coil wire should fire a spark to the engine every time the points are opened. Be careful- - - -you're holding onto 20,000 volts or so. Don't get too close to the end of the wire!
4. Good spark at the coil wire- - - -check the distributor rotor to be sure it's in good condition and the correct height for the cap- - - -a short rotor and a tall cap equals no spark to the plugs. Also make sure the distributor shaft is turning- - - -a stripped timing gear will definitely cause a no start condition- - - - -no operation of the valves, distributor, or oil pump!
If the spark is getting from the coil, to the distributor, to the spark plugs, try changing to a new set of spark plugs. I have seen plugs that get a good fuel soaking from flooding that will never fire again- - - -no matter how well they're dried out or cleaned. That's also a very rare, but confirmed situation. I spent 4 hours once trying to start an Oldsmobile 350 that had been badly flooded, did all the above diagnostics, and finally got it running by changing to a new set of spark plugs!
Jerry
