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Ford 300 Big Six specs: 300 ci (4.9L) 6-cylinder, 4.00 x 3.98 in (101.6 x 101.1 mm) bore and stroke, 8.9:1 compression. Rated 165-170 hp, 1965–1971.
The Ford 300 Big Six is close to square: 4" bore against 3.98" stroke, within 0.5%, which splits the difference between a high-revving layout and a torque layout. The 3.98" stroke puts mean piston speed at 4,000 ft/min around 6,050 RPM, which is where a production bottom end is generally considered at its limit. Each of the 6 cylinders displaces 50.0 ci (819 cc).
8.9:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 7 engines in the 240/300 Big Six family, the largest at 300 ci. 7 factory variants share these dimensions, rated from 165 to 170 hp across 1965–1971.
| Displacement | 300 ci / 4.9 L |
|---|---|
| Bore | 4" |
| Stroke | 3.98" |
| Cylinders | 6 |
| Configuration | I6 |
| Compression ratio | 8.9:1 |
| Bore/stroke ratio | 1.005 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 165–170 hp |
| Years | 1965–1971 |
| Bore/stroke character | 1.005 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,980 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 50.0 ci |
| Static compression | 8.9:1 — low by modern standards, generally happy on regular pump fuel |
Each link opens the calculator with this engine's specs already filled in.
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 1965 | 170 hp | 300 Big Six |
| 1966 | 170 hp | 300 Big Six |
| 1967 | 170 hp | 300 Big Six |
| 1968 | 165 hp | 300 Big Six |
| 1969 | 165 hp | 300 Big Six |
| 1970 | 165 hp | 300 Big Six |
| 1971 | 165 hp | 300 Big Six |