Valve And Ignition Timing Of Four-Cycle Hit And Miss Engines

(Page 2 of 2)

Bud Motry
August/September 1988
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Let's go over the relationship of the camshaft and gear to the crankshaft gear again. There are three meshed gears on your engine-the governor gear is not timed-forget it. There are also TWO LOBES on your camshaft gear. The shorter lobe operates the push rod to trip the igniter at the proper time. The larger lobe operates the same push rod to open the exhaust valve. In order to check the accuracy of the timing marks and the camshaft to crankshaft gear, you may do this:

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With the piston at the end of the intake stroke, the connecting rod at its outer limit, continue to turn the flywheels. At about 30 to 45 degrees (in reference to a revolution of the crankshaft) beyond the con/rod outer limit, the push rod is at its most rearward position. This position should permit the trip arm, which is attached by a bracket to the push rod, to engage the igniter lever. The trip arm bracket is adjustable on the push rod. There should be a spring action to hold the trip arm against the igniter lever. As you continue to turn the flywheel, on the compression stroke, the igniter should trip when the piston is at top Dead Center. A slight adjustment of the trip arm bracket may be necessary. There are timing marks on the two gears, but they are difficult to locate unless the gears are disassembled.

I might mention, with this type of ignition system or with any Webster-Tri-polar, or Wico EK ignition system that uses the trip mechanism, speed of rotation of the flywheels has little to do with ease of starting. Spring action should take care of the quick movement that is required.

The connections for your ignition with the battery and low tension coil system is simple. One battery lead is connected to the engine block for ground. The other battery lead is connected to one terminal of the coil. The other terminal of the coil is connected to the insulated terminal of the igniter. If you wish to use a cut-off switch in your system, connect it to the lead from your coil to the igniter.

The instructions outlined here apply to any type of ignition system that uses an igniter, whether it is used with a magneto or a battery and coil.

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