Jeep 258 Specs

Jeep 258 engine specs: 258 ci (4.2L), 6-cylinder, 3.75" bore x 3.9" stroke, 9.2:1 compression.

Dimensions

Displacement258 ci / 4.2 L
Bore3.75"
Stroke3.9"
Cylinders6
Compression ratio9.2:1
Bore/stroke ratio0.962
Piston deck clearance0.022"

Construction

Block materialcast iron
Head materialcast iron
ValvetrainOHV
Fuel typegas
Advertised HP112 hp

What these numbers mean

Bore/stroke character0.962 — square — bore and stroke are within 5%, a balanced compromise
Mean piston speed at 6,000 RPM3,900 ft/min — in the range typical of performance street engines
Displacement per cylinder43.0 ci
Static compression9.2:1 — low by modern standards, generally happy on regular pump fuel

Cylinder head

Chamber volume67.84 cc
Rocker ratio1.6:1
Lifter typehydraulic

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Similar engines

Source: NHRA blueprints — nhra.net blueprints

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