Compression Check: Testing and Inspection

AllData Editors Note - Ford does not provide a cranking pressure specification, only an acceptable range.

1. Warm engine to normal operating temperature, then remove spark plugs and set throttle plates to wide open position.
2. Install a suitable compression gauge in cylinder No. 1 spark plug hole.
3. Install an auxiliary starter switch in the starting circuit.
4. With key off, using auxiliary starter switch, crank engine at least five compression strokes and record highest reading.
5. Repeat test on each cylinder.
6. Indicated compression pressures are within specification if the lowest reading cylinder is within 25% of the highest reading.