GMC L65 Specs: 4.00 x 3.48 in, 245 hp

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GMC L65 specs: 350 ci (5.7L) 8-cylinder, 4.00 x 3.48 in (101.6 x 88.4 mm) bore and stroke, 8.5:1 compression. Rated 245 hp, 1971–1976.

The GMC Small Block Chevy (L65) is oversquare — the 4" bore exceeds the 3.4799" stroke by 14.9% — a layout that favors airflow and RPM over leverage at the crank. The 3.4799" stroke puts mean piston speed at 4,000 ft/min around 6,900 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 43.8 ci (717 cc).

8.5:1 on iron heads is low by modern standards and generally happy on regular pump fuel.

It is one of 27 engines in the Small Block Chevy family, sitting between the 265 ci and 400 ci members. 6 factory variants share these dimensions, rated at 245 hp across 1971–1976.

Dimensions

Displacement	350 ci / 5.7 L
Bore	4"
Stroke	3.4799"
Cylinders	8
Configuration	V8
Compression ratio	8.5:1
Bore/stroke ratio	1.149

Construction

Block material	cast iron
Head material	cast iron
Valvetrain	OHV
Fuel type	gas
Firing order	1-8-4-3-6-5-7-2
Advertised HP	245 hp
Years	1971–1976

Factory ratings and camshaft by year

Year	Version	HP @ rpm	Torque @ rpm	Comp.	Duration int / exh	Valve lift int / exh	LSA
1971	gross	245 @ 4800	350 lb-ft @ 2800	8.5:1	280° / 288°	0.390" / 0.410"	113°

Factory specification sheet. Durations are the factory's advertised figures at the basis printed on the sheet, not duration at .050" lift; lobe separation is calculated from the printed valve timing.

What these numbers mean

Bore/stroke character	1.149 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves
Mean piston speed at 6,000 RPM	3,480 ft/min — conservative for a street engine
Displacement per cylinder	43.8 ci
Static compression	8.5:1 — low by modern standards, generally happy on regular pump fuel

Run the numbers for this engine

Each link opens the calculator with this engine's specs already filled in.

• Displacement from bore and stroke (calculator)
• Static and dynamic compression ratio calculator
• Piston ring gap for this bore
• Piston speed at any RPM
• Horsepower to torque at any RPM
• What size carburetor (CFM calculator)

Variants sharing these dimensions (6)

These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.

Year	Advertised HP	Code
1971	245 hp	L65
1972	—	L65
1973	—	L65
1974	—	L65
1975	—	L65
1976	—	L65

What cars have the L65?

13 factory vehicles, 1969–1976. Each year opens that model's engine table.

• Chevrolet Camaro: 1969, L65, 250 hp; 1970, L65, 250 hp; 1971, L65, 245 hp; 1972, L65, 165 hp; 1973, L65, 145 hp; 1974, L65, 145 hp; 1975, L65, 145 hp
• Chevrolet Chevelle: 1969, L65, 250 hp; 1970, L65, 250 hp; 1971, L65, 245 hp; 1972, L65, 165 hp; 1973, L65, 145 hp; 1974, L65, 145 hp; 1975, L65, 145 hp; 1976, L65, 145 hp
• Chevrolet El Camino: 1969, L65, 250 hp; 1970, L65, 250 hp; 1971, L65, 245 hp; 1972, L65, 165 hp; 1973, L65, 145 hp; 1974, L65, 145 hp; 1975, L65, 145 hp; 1976, L65, 145 hp
• Chevrolet Malibu: 1969, L65, 250 hp; 1970, L65, 250 hp; 1971, L65, 245 hp; 1972, L65, 165 hp; 1973, L65, 145 hp; 1974, L65, 145 hp; 1975, L65, 145 hp
• Chevrolet Nova: 1969, L65, 250 hp; 1970, L65, 250 hp; 1971, L65, 245 hp; 1972, L65, 165 hp; 1973, L65, 145 hp; 1974, L65, 145 hp; 1975, L65, 145 hp
• Chevrolet Caprice: 1969, L65, 250 hp; 1975, L65, 145 hp; 1976, L65, 145 hp
• GMC Sprint / Caballero: 1971, L65, 245 hp; 1972, L65; 1973, L65; 1974, L65; 1975, L65; 1976, L65
• Chevrolet Monte Carlo: 1974, L65, 145 hp; 1975, L65, 145 hp; 1976, L65, 145 hp
• GMC C/K Pickup: 1975
• Chevrolet K5 Blazer: 1975, L65, 145 hp
• GMC Jimmy: 1975, L65, 145 hp
• Chevrolet Monza: 1975, L65, 125 hp
• Chevrolet Impala: 1976, L65, 145 hp

Similar engines

• GMC 350 — 350 ci
• GMC Small Block Chevy (1969) — 350 ci
• GMC L05 — 350 ci
• GMC L31 — 350 ci
• GMC L48 — 350 ci
• GMC LM1 — 350 ci
• Buick 1979 350 155HP — 350 ci
• Buick 1979 350 160HP — 350 ci

← All Small Block Chevy engines