Spark Plug Specifications for a 350 Small Block

by Teri Olcott
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The 350 small block engine first appeared as a high-performance V-8 option for the 1967 Chevy Camaro. In 1968, it could be ordered with the Chevy Nova. In 1969, any Chevy vehicle could be ordered with a 350 engine. Spark plugs for the 350 engine are on the sides of the engine, outside the cylinder heads. Depending on the year of the engine, the spark plugs may stick straight out or set at a 35-degree angle. Eight spark plugs are required to keep the engine running smoothly.

Spark Plug Gap

Spark plugs for the Chevy 350 engine are readily available from any auto parts store. Spark plugs come pre-gapped, but you should always verify the gap with a spark plug gap tool. The gap for a 350 small block should be 0.035 inches.

Spark Plug Torque

Torque is a crucial aspect of installing spark plugs. Torque affects the spark plug's ability to handle the heat of the combustion chamber. The correct torque setting for a 350 small block engine spark plug is 20 ft.-lbs.

Spark Plug Size

From 1967 to 1970, the 350 small block engine used 14 mm spark plugs and a compression washer for a tight seal. Starting in 1971, a tapered seat did away with the need for a compression washer.

Firing Order

The routing of the spark plug wires from the distributor cap on the engine to the individual spark plugs in each cylinder determines the sequence in which the spark plugs fire. Each of the eight cylinders on the 350 engine requires a spark at the correct time. The firing order on the 350 small block engine is 1-8-4-3-6-5-7-2.

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