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Engine Compression

Check engine compression with engine at normal operating temperature at specified cranking speed, all spark plugs removed and throttle wide open.

CAUTION: Release fuel system pressure before checking engine compression.
COMPRESSION SPECIFICATIONS

Application Specification
Compression Ratio
4.0L 9.5:1
6.0L 11.0:1
Compression Pressure (1)
4.0L 160-170 psi (11.2-12.0 kg/cm2 )
6.0L 200-240 psi (14.1-16.9 kg/cm2 )
Maximum Variation Between Cylinders 10 psi (.70 kg/cm2 )
(1) Minimum cranking speed is 300 RPM with all spark plugs removed and throttle held wide open.
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