Buick 300ci 10.25:1 Specs

Buick Buick 300ci · 3.75" × 3.4" · 10.25:1 engine specs: 300 ci (4.9L), 8-cylinder, 3.75" bore x 3.4" stroke, 10.25:1 compression.

Dimensions

Displacement300 ci / 4.9 L
Bore3.75"
Stroke3.4"
Cylinders8
Compression ratio10.25:1
Rod length5.963"
Rod ratio1.754
Bore/stroke ratio1.103
Piston deck clearance0.01"

Construction

Induction1-4
Advertised HP250 hp
Years1965

What these numbers mean

Bore/stroke character1.103 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves
Mean piston speed at 6,000 RPM3,400 ft/min — conservative for a street engine
Rod ratio1.754 — long — less side loading on the cylinder wall, favours high RPM
Displacement per cylinder37.5 ci
Static compression10.25:1 — in the range that usually runs on pump premium

Cylinder head

Intake valve diameter1.818"
Exhaust valve diameter1.38"
Chamber volume51.12 cc
Rocker ratio1.6:1
Lifter typehydraulic

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Similar engines

Source: NHRA blueprints — nhra.net blueprints

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