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Ford 1974 170 105HP specs: 170 ci (2.8L) 6-cylinder, 3.50 x 2.94 in (88.9 x 74.7 mm) bore and stroke, 9.872:1 compression. Rated 105 hp, 1974. OHV.
The Ford 1974 170 105HP is oversquare — the 3.5" bore exceeds the 2.94" stroke by 19.0% — a layout that favors airflow and RPM over leverage at the crank. The 2.94" stroke does not reach 4,000 ft/min of mean piston speed until about 8,150 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. A rod ratio of 1.604 is in the range most production engines fall in. Each of the 6 cylinders displaces 28.3 ci (464 cc).
9.872:1 on iron heads is in the range that usually runs on pump premium; iron holds heat, so treat it as the less forgiving side of that range.
It is one of 4 engines in the Ford 170ci family, all of them 170 ci — the differences between them are in compression, heads and rating, not displacement.
| Displacement | 170 ci / 2.8 L |
|---|---|
| Bore | 3.5" |
| Stroke | 2.94" |
| Cylinders | 6 |
| Configuration | I6 |
| Compression ratio | 9.872:1 |
| Rod length | 4.715" |
| Rod ratio | 1.604 |
| Bore/stroke ratio | 1.19 |
| Piston deck clearance | 0.025" |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 105 hp |
| Years | 1974 |
| Bore/stroke character | 1.190 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,940 ft/min — conservative for a street engine |
| Rod ratio | 1.604 — moderate — the range most production V8s fall in |
| Displacement per cylinder | 28.3 ci |
| Static compression | 9.872:1 — in the range that usually runs on pump premium |
| Intake valve diameter | 1.577" |
|---|---|
| Exhaust valve diameter | 1.276" |
| Chamber volume | 48.32 cc |
| Rocker ratio | 1.5:1 |
| Lifter type | hydraulic |
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