THEORY OF OPERATION—“K” SERIES FC290V
ENGINE
COMPRESSION RELEASE OPERATION
Camshaft Push Rod Spring Exhaust Valve Tappet Weight Tab
Camshaft Gear M49467
Theory of Operation: The compression release on this engine consists of a release tab, weight and spring that are mounted on gear of the camshaft The release tab holds the exhaust valve tappet and push rod off its seat during a portion of the compression stroke. The release tab is connected to the weight and the spring holds the weight in at low rpms. As the engine starts and the rpms increase, the weight overcomes the spring and moves out. As it moves out, the release tab moves in until it clears the valve tappet. The exhaust valve seats properly and full compression is obtained. Valve lash is important for correct operation. Too much lash and compression will be high; too little and compression will be low.
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