Chevrolet 350 Engine Specsby Moss Strohem
The 350 C. I. V8 engine is one of Chevrolet's most popular and mass-produced engines. Introduced in 1967, it was based on the same cylinder block design of many small block engines dating back to the original 265 C. I. V8 engine introduced in 1955. It has been used in millions of cars and trucks up to the time production ended. Still available as a crate engine from GM, it continues to be a popular performance engine platform with parts availability from both General Motors and automotive aftermarket parts manufacturers.
Also known as the General Motors 5.7L V8 engine, the 350 achieves its displacement by using a 4 inch cylinder bore and a crankshaft stroke of 3.48 inches. The engine uses a wet-sump oiling system with a 5 quart oil pan. The pistons have a 1.46 inch compression height and are manufactured from either cast aluminum, or, in the case of the high performance engine models, forged aluminum. The connecting rods are 5.7 inches in length and are made of forged steel. The overhead valve (OHV) design places the camshaft on a centerline directly above the crankshaft.
Cylinder Head Design
Since it's inception, the small block Chevy, including the 350, has used an overhead valve design that uses two pushrod actuated valves, one for each the intake and exhaust valves. Standard performance 350s initially used 1.94 inch intake valves and 1.5 inch exhaust valves. The cylinder heads were manufactured from cast iron and typically had port volumes of approximately 155cc and around 60 to 70cc for the intake and exhaust runners, respectively. Early 350 high performance engines (used in Corvettes and Z28 Camaros) used larger valves with smaller 64cc combustion chambers for improved airflow and higher compression. Additionally, the higher output engines used 4V (4 barrels/venturi) carburetors along with more aggressive camshaft timing.
Power output varied depending on the engine model. The initial 350 offered in the 1967 Camaro was rated at 295 horsepower. That same engine was offered in other models and by 1970, several variants of the same engine were being used across Chevrolet's model lineup, including trucks. Power output is as follows: 1970 350 2V: 250 horsepower 1970 350 4V: 300 horsepower 1970 350 4V: 350 horsepower 1970 350 4V: 370/360 horsepower (LT1, Corvette/Z28) In 1971, reduced compression (due to tighter emission standards) lowered output slightly and in 1972, power output was measured at the rear wheels resulting in what appeared to be significantly lower horsepower ratings. While keeping the general design of the engine the same, GM modernized the cylinder head and induction systems in the late 1980s. As a result, power output began to climb once again. Toward the end of the 350s production, high performance versions used in the Corvette and Camaros were once again producing upwards of 300 horsepower (1996 Gen. II 350 LT1: 330 horsepower).
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