Mechanical Inspection: Compression
Release fuel system pressure. See FUEL PRESSURE RELEASE under FUEL SYSTEM. Install a remote starter switch to starter circuit. Remove spark plugs and install a compression gauge. Crank engine a minimum of 5 strokes and record highest compression reading. See COMPRESSION SPECIFICATIONS table.
COMPRESSION SPECIFICATIONS
| Application | Specification | ||||
|---|---|---|---|---|---|
| Compression Ratio | |||||
| S-Type | |||||
| 3.0L | 10.5:1 | ||||
| 4.0L | 10.75:1 | ||||
| XJR, XJ8 & XK8 | |||||
| Normally Aspirated | 10.75:1 | ||||
| Supercharged | 9.0:1 | ||||
| Compression Pressure | (1) | ||||
| Maximum Variation Between Cylinders | 25% | ||||
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