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Ford Essex 4.2 specs: 256 ci (4.2L) 6-cylinder, 3.811 x 3.74 in (96.8 x 95 mm) bore and stroke. OHV. Rod ratio and piston speed worked out.
The Ford Essex 4.2 is close to square: 3.811" bore against 3.74" stroke, within 1.9%, which splits the difference between a high-revving layout and a torque layout. The 3.74" stroke puts mean piston speed at 4,000 ft/min around 6,400 RPM, which is where a production bottom end is generally considered at its limit. Each of the 6 cylinders displaces 42.7 ci (699 cc).
It is one of 2 engines in the Essex V6 family, all of them 256 ci — the differences between them are in compression, heads and rating, not displacement.
| Displacement | 256 ci / 4.2 L |
|---|---|
| Bore | 3.811" |
| Stroke | 3.74" |
| Cylinders | 6 |
| Bore/stroke ratio | 1.019 |
| Block material | cast iron |
|---|---|
| Head material | aluminum |
| Valvetrain | OHV |
| Fuel type | gas |
| Bore/stroke character | 1.019 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,740 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 42.7 ci |
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