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Jeep AMC 327 specs: 327 ci (5.4L) 8-cylinder, 4.00 x 3.252 in (101.6 x 82.6 mm) bore and stroke, 8.7:1 compression. Rated 250 hp. Rod ratio and piston speed.
The Jeep AMC 327 is oversquare — the 4" bore exceeds the 3.252" stroke by 23.0% — a layout that favors airflow and RPM over leverage at the crank. The 3.252" stroke does not reach 4,000 ft/min of mean piston speed until about 7,400 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 8 cylinders displaces 40.9 ci (670 cc).
8.7:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 3 engines in the Vigilante family, all of them 327 ci — the differences between them are in compression, heads and rating, not displacement. Factory fitments include the Wagoneer, Gladiator.
| Displacement | 327 ci / 5.4 L |
|---|---|
| Bore | 4" |
| Stroke | 3.252" |
| Cylinders | 8 |
| Compression ratio | 8.7:1 |
| Bore/stroke ratio | 1.23 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 250 hp |
| Bore/stroke character | 1.230 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,252 ft/min — conservative for a street engine |
| Displacement per cylinder | 40.9 ci |
| Static compression | 8.7:1 — low by modern standards, generally happy on regular pump fuel |
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