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3 good tune-up tips for beginners, back to back (#3)
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Posted by RKS on May 31, 1999 at 05:02:04 from (171.211.172.216):
(3) - THE REQUIREMENT FOR USING A TIMING LIGHT (STROBE LIGHT): OK, so you have the points, condenser, and new plugs installed and everything is set on the proper gap as recommended by the mfg. The tractor cranks and runs beautifully. You're finished, right? Well, if you're happy, I guess so. But, do you want that other horse power that you are missing, and do you want the tractor to crank easily and run and cool more effectively? Most people say yes, so consider finishing the job with a timing light. The only way to know if the spark timing is happening at the correct position of the compression stroke is to "freeze" it and look. Since the engine, even at low rpm, is spinning too fast for the human eye to see, and even if you could see the engine position, you can't see the spark inside. So, the solution is to use a timing light. The light connects to the battery for power (there are a rare few that only use the spark energy to fire the strobe light) and a lead connects to the spark plug wire. The mfg has designated the cylinder for you to use in the tune-up specifications and usually this is also the number 1 piston/cylinder. When the spark occurs, the light is energized (it's a very fast reacting neon type light) and flashes, freezing the rotation of the crankshaft pulley or flywheel pulley, so that the human eye can measure the relative position of the timing marks and how they are positioned when the spark occurs in reference to a "pointer." A very tiny error in setting the point gap (an error beyond human capacity to avoid, even if great care is taken setting the points) will be translated into a significant error in the timing. This is because changing the point setting alters the position of the spark (the degrees of error are more easily controlled in the rotation of the engine than in the setting of the point gap). However, changing the timing has less affect on the dwell angle, (which setting the points accurately closely approximates) and therefore should be done after the points are set accurately. Setting the points most accurately also requires a dwell angle measuring instrument, usually combined as a "dwell-tach," and is not absolutely required, unless you want to be a purist. The timing mark can be made to move in relation to the pointer position and set to mfg's specifications, by loosening the distributor mounting bolts just to the point they prevent the distributor from being turned easily by hand. Then as one observes the timing marks with the strobe, the distributor is tuned gently until the proper position is found. Do not turn rapidly or you will cause backfiring and/or total loss of reference and may be unable to restart the engine. Remember that tightening the bolts will move the timing slightly, so tighten slowly while observing the timing until the bolts are fully tight. RKS
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