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How to Identify 305 & 350 Engines

by Floyd Drake III

Chevrolet 305 and 350 cubic-inch engines are virtually identical, differing only in cylinder bore size. To identify any Chevrolet small-block V-8 engine, the engine ID number must be matched to a listing of suffix codes, which identifies the details of the engine in question, including original application, horsepower, year of manufacture and technical specifications. Visual methods of identification, including tags and labels on the engine or in the engine compartment, exist. However, these labels may have worn off or modifications may have been made to the engine, rendering the tags useless for positive engine identification.

Step 1

Look for the engine ID number. According to Year One's Chevrolet Engine Identification page, small-block Chevrolet engine ID numbers are on the left (passenger) side of the engine block, forward, below the cylinder head and near the alternator. Loosening or removal of the alternator may be necessary to see the number.

Step 2

Decipher the ID number prefix. The ID number stamped on the block consists of at least eight positions. According to the Nasty Z28 site, the prefix portion begins with a letter followed by four digits indicating the month and day of manufacture. The letter identifies the engine manufacturing plant. The date "0225" translates as February 25.

Identify the suffix portion of the ID number. Nasty Z28 identifies the suffix portion as the final three letters of the engine ID number. Complete identification information is provided when matched to the suffix identification charts found on Nasty Z28s website.

Tip

  • Matching the suffix portion of the engine ID number properly identifies the engine as a 305 or 350 cubic-inch. If a bore measurement is to be taken, Popular Hot Rodding identifies the 305s small bore at 3.736 inches. Both the 305 and 350 have the same 3.48-inch stroke.

Items you will need

  • A Chevrolet engine ID number listing

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