Chevy 350 Small Block Specifications

Creatas/Creatas/Getty Images

The 350 small block engine belongs to Chevrolet's series of small block V8 engines that was first built in 1955. It produced 180 horsepower, and was introduced into the Corvette. It was also called the Mouse due to its compact design, sporting short engine skirts, thin-walled cast, and a simple valvetrain. Due to its popularity, other automotive companies such as Pontiac, Oldsmobile, Ford, and Chrysler began designing their own compact V8 high performance engines.

Evolution of the 350 Small Block Engine

With the compact engine competition underway, Chevrolet redesigned the small block engine and gradually increased displacements and other variations in performance and interchangeability. The 350 was released as the 350/290, 350 High Output (HO) Turn-Key, 350 HO Deluxe, 350 HO Base, 350ZZ4 Turn-Key, 350 ZZ4 Base, 350 ZZ4 Partial, and the Ram Jet 350. These variants share the same basic features such as bore and stroke of 4 by 3.48 inches, a cast-iron block with four-bolt main caps, powdered metal steel connecting rods, and 1.94 intake/1.50 exhaust valve size.

The 350/290 HP utilized a nodular iron crankshaft, cast aluminum pistons, and hydraulic flat tappet camshaft. These traits can also be found on the HO Turn-Key, HO Deluxe, and HO Base. However, it was the only variant that had a camshaft lift of 0.450 intake/0.460 exhaust, iron cylinder heads using 76cc chambers, and a compression ratio of 8.5 to 1. It was also the only variant with 87 octane as the recommended fuel. It generated a maximum of 5,100 revolutions per minute (rpm).

The HO Turn-Key, HO Deluxe, and HO Base variants were similar to the 350/290 in terms of their crankshaft, pistons, and camshaft. However, these variants also shared unique characteristics different from the others, such as a camshaft lift of 0.435 intake/0.460 exhaust, and Vortec iron cylinder heads using 64cc chambers. Their compression ratio was 9.1 to 1, and utilizes a cast iron long-style water pump. The recommended fuel was 92 octane, and generated a maximum of 5,500 rpm.

The ZZ4 series differed from the other variants with a forged steel crankshaft, high-silicon aluminum pistons with offset pins, steel hydraulic roller camshaft, 0.474 intake/0.510 exhaust camshaft lift, and aluminum cylinder heads using 58cc chambers. The compression ratio was 10 to 1, and the engine used 92 octane fuel. It generated a maximum of 5,800 rpm and was designed for street vehicles and off-road vehicles prior to 1977.

The Ram Jet 350 is the latest variant available. It features the latest MEFI 4 controller for all-around drivability, and the Ram Jet induction system. Unlike the old variants, the Ram Jet features a cast iron crankshaft, hypereutectic aluminum pistons, a hydraulic roller camshaft, 0.431 intake/0.451 exhaust camshaft lift, and Vortec iron cylinder heads using 64cc chambers. The compression ratio is 9.4 to 1, and it can generate a maximum of 5,500 rpm. Similar to the ZZ4 series, its recommended fuel is 92 octane. Vehicles designed in 1976 or earlier can be fitted with the Ram Jet engine, providing them with an electronic injection system and wiring harness, as long as they are equipped with a carburetor.