Pistons and rings
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===Special notice on Keith Black piston top ring end gap=== | ===Special notice on Keith Black piston top ring end gap=== | ||
| − | + | The Keith Black piston's unique thermal conductivity, ring location and varied end use requires special attention be paid to top ring end gap. KB pistons make more HP by reflecting heat energy back into the combustion process and, as a result, the top ring runs hotter and requires additional end clearance. Increasing ring end gap does not affect performance or oil control because normal end gaps are realized at operating temperatures. Failure to provide sufficient top ring end gap will cause a portion of the top ring land to break as the ring ends butt and lock tight in the cylinder. The broken piece may cause further piston or engine damage. Safe top ring end gaps can be found by multiplying the bore diameter by the appropriate ring end gap factor from the clearance chart below. | |
'''Example:''' 4" bore "Street Normally Aspirated" = 4" bore x 0.0065 = 0.026 top ring end gap. NOTE: Second ring end gaps do not need extra clearance. Dyno and track testing has shown that 34 degrees or less total ignition timing makes the best HP and time. Excessive spark advance, lean fuel mixture or too much compression for the fuel and cam used will make heat sufficient to butt piston rings with as much as 0.060" ring end gap. The entire top land can expand enough to contact the cylinder walls, when close to melt down temperatures are reached. | '''Example:''' 4" bore "Street Normally Aspirated" = 4" bore x 0.0065 = 0.026 top ring end gap. NOTE: Second ring end gaps do not need extra clearance. Dyno and track testing has shown that 34 degrees or less total ignition timing makes the best HP and time. Excessive spark advance, lean fuel mixture or too much compression for the fuel and cam used will make heat sufficient to butt piston rings with as much as 0.060" ring end gap. The entire top land can expand enough to contact the cylinder walls, when close to melt down temperatures are reached. | ||
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