GMC 230 Specs

GMC 230 engine specs: 230 ci (3.8L), 6-cylinder, 3.875" bore x 3.25" stroke, 8.5:1 compression.

Dimensions

Displacement230 ci / 3.8 L
Bore3.875"
Stroke3.25"
Cylinders6
Compression ratio8.5:1
Bore/stroke ratio1.192
Piston deck clearance0.011"

Construction

Block materialcast iron
Head materialcast iron
ValvetrainOHV
Fuel typegas
Advertised HP140 hp

What these numbers mean

Bore/stroke character1.192 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves
Mean piston speed at 6,000 RPM3,250 ft/min — conservative for a street engine
Displacement per cylinder38.3 ci
Static compression8.5:1 — low by modern standards, generally happy on regular pump fuel

Cylinder head

Intake valve diameter1.725"
Exhaust valve diameter1.505"
Chamber volume69.6 cc
Rocker ratio1.75:1
Lifter typehydraulic

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Similar engines

Source: NHRA blueprints — nhra.net blueprints

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