Octane Rating Engine Cylinder Height determines the Compression Ratio (C.R.). The C.R. is a primary variable for the knock testing methods. The dial indicator assembly or the digital counter assembly is the measurement devices that are used to track the movement of the cylinder in the clamping sleeve. Both of them require indexing at a critical C.R. , so that the cylinder height measurements are standardized.
The standard test method is the indexing compression pressure method.
The following steps shall be performed as quickly as possible to ensure that the pressure readings represent hot engine conditions.
(1) Shut the octane rating engine down, and positioning the engine power switch to off.
(2) Remove the detonation pickup and install the gage assembly in the combustion chamber pickup hole.
(3) Determine the prevailing barometric pressure and using below Fig., read the compression pressure expected for cylinder height instrument indexing.
(4) Restart the octane engine and operate in a motoring mode only.
(5) Observe the compression pressure gage reading and adjust the cylinder height so that the expected compression pressure is indicated. Release the pressure once or twice using the deflator valve and make any required change in cylinder height so that the expected compression pressure is obtained.
(6) For C.R. digital counter assemblies, the basic digital counter reading is set to 930. For dial indicator assemblies, the basic dial indicator reading is set to 0.352 in.
(7) Shut the octane rating unit down, remove the compression pressure gage assembly, install the detonation pickup with a new gasket, and tighten the pickup.
More details about the basic cylinder height setting on octane rating engine with SXCP panel, please see “How to Reset Cylinder Height (for Basic Cylinder Height Setting) On SXCP Octane Engine Panel?”.