Chevrolet L34 Specs: 4.125 x 3.766 in, 350 hp

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Chevrolet L34 specs: 402 ci (6.6L) 8-cylinder, 4.125 x 3.766 in (104.8 x 95.7 mm) bore and stroke. Rated 350 hp, 1970. Used in the Chevrolet Camaro. OHV.

The Chevrolet 402ci (L34) is oversquare — the 4.125" bore exceeds the 3.766" stroke by 9.5% — a layout that favors airflow and RPM over leverage at the crank. The 3.766" stroke puts mean piston speed at 4,000 ft/min around 6,350 RPM, which is where a production bottom end is generally considered at its limit. A rod ratio of 1.629 is in the range most production engines fall in. Each of the 8 cylinders displaces 50.3 ci (823 cc).

It is one of 8 engines in the Chevrolet 402ci family, all of them 402 ci — the differences between them are in compression, heads and rating, not displacement.

Dimensions

Displacement402 ci / 6.6 L
Bore4.125"
Stroke3.766"
Cylinders8
ConfigurationV8
Rod length6.136"
Rod ratio1.629
Bore/stroke ratio1.095

Construction

Block materialcast iron
Head materialcast iron
ValvetrainOHV
Fuel typegas
Advertised HP350 hp
Years1970

What these numbers mean

Bore/stroke character1.095 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves
Mean piston speed at 6,000 RPM3,766 ft/min — in the range typical of performance street engines
Rod ratio1.629 — moderate — the range most production V8s fall in
Displacement per cylinder50.3 ci

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