Pontiac V8 Engine Codes and Specs

Pontiac V8 Long Block

Pontiac V8 engine codes and casting numbers help identify your engine’s displacement, production date, horsepower rating, original vehicle application, assembly plant, and production year. This guide explains how to locate and decode the Pontiac Partial VIN, engine codes, casting numbers, block date codes, and assembly plant codes for Pontiac 326, 350, 389, 400, 421, 428, and 455 V8 engines.

How to Locate the Pontiac Engine Partial VIN and Engine Codes

Pontiac Engine Code Location

Pontiac Engine Partial VIN

The Pontiac engine Partial VIN is stamped on the front passenger side of the engine block, just above the oil pan rail and to the left of the timing cover.

From 1955 through early 1967, the engine Partial VIN consists of the last six digits of the vehicle VIN.

From late 1967 through 1981, the engine Partial VIN consists of nine characters. The last six digits match the last six digits of the vehicle VIN.

• 1st Character: “2” = Pontiac Division
• 2nd Character: Model year
• 3rd Character: Assembly plant
• Last 6 Characters: Match the last six digits of the vehicle VIN

Example Partial VIN: 28P123456

• 2 = Pontiac Division
• 8 = 1968 model year
• P = Pontiac, Michigan assembly plant (use the correct plant letter from your chart if you prefer another example)
• 123456 = Matches the last six digits of the vehicle VIN

Pontiac Engine Assembly Plant Code

• A = Atlanta
• B = Baltimore
• C = California
• E = Linden, NJ
• G = Framingham, MA
• K = Kansas City, MO
• L = Van Nuys
• R = Arlington, TX
• X = Kansas City, KN
• 1 = Oshawa, Ontario
• Z = Fremont, CA
• S = California- Southgate

Engine Code

Before 1965, Pontiac engine codes used a combination of numbers and letters. Beginning in 1965, Pontiac switched to a two-letter engine code stamped just below the passenger-side cylinder head.

The first letter of the engine code identifies the transmission application:

• W = Manual transmission
• Y = Automatic transmission
• Z = Automatic transmission
• X = Manual or automatic transmission

Use the Pontiac Engine Code Chart below to identify the engine’s original displacement, horsepower rating, transmission, and vehicle application.

Engine Unit Number

The Pontiac Engine Unit Number is stamped under the passenger-side cylinder head, directly above the engine code. This 6- or 7-digit number is the engine’s sequential production number and can help verify the engine’s original production sequence when used with the Partial VIN, engine code, and casting number.

Block Casting Number

Pontiac Block Casting Number

The Pontiac block casting number identifies the engine block and helps determine the engine’s displacement, production year, and original application.

• 1955–1963: The block casting number is located on the passenger side of the engine block.
• 1964–1967: The block casting number is located at the rear of the engine block, near the distributor.
• 1968–1981: The block casting number is located on the ledge at the rear of the engine block behind cylinder No. 8.

Engine Block Date Code

The Pontiac engine block date code identifies the engine block’s production date and is located at the rear of the engine, near the distributor.

The date code consists of three or four characters. The first letter represents the month, the next one or two digits represent the day of the month, and the last digit represents the year of manufacture.

Example: A128 = January 12, 19*8.

Note: The last digit represents the year, but additional information is required to determine the correct decade. For example, an 8 could represent 1958, 1968, or 1978.

Beginning in 1969, Pontiac also stamped the last two digits of the model year on the rear of the engine block near the distributor, making it easier to determine the correct production year.

Month Code

The first letter of the Pontiac engine block date code identifies the month the engine block was cast.

• A = January
• B = February
• C = March
• D = April
• E = May
• F = June
• G = July
• H = August
• I = September
• J = October
• K = November
• L = December
• M = December (1967 only)

Visual differences of a Pontiac V8 Engine

The Valley Cover

The valley cover provides one of the quickest ways to identify the approximate production year of a Pontiac V8 engine. Locate the PCV valve on the valley cover to help determine the engine’s production period.

If the PCV valve is located at the rear of the valley cover, the engine was produced between 1955 and 1966.

If the PCV valve is located at the front of the valley pan, the engine was produced between 1967 and 1981.

Starter Mounting

Starter motor location is another quick way to identify a Pontiac V8 engine.

From 1964 through 1981, the starter motor was mounted directly to the engine block. On earlier engines (1955–1963), the starter was mounted to the bellhousing.

Freeze Plugs

The number of freeze plugs on each side of the engine block can help identify the production year of a Pontiac V8 engine.

1955–1966 engines have two freeze plugs on each side of the block.

1967–1981 engines have three freeze plugs on each side of the block.

Engine Size Stamping

Engine displacement markings can also help identify a Pontiac V8 engine.

1955–1967: Engine displacement was not stamped on the engine block.

1968–1969: Only the 428 engines had the displacement cast between the freeze plugs.

1970–1979: The 350, 400, and 455 engines had the displacement stamped on the left front of the engine block.

Motor mounts:

The number of engine mount bolt holes can also help identify the production year of a Pontiac V8 engine.

1959–1969: Blocks have two engine mount bolt holes on each side.

1970–1976: Blocks have five engine mount bolt holes on each side.

1977–1979: Blocks have three engine mount bolt holes on each side.

Pontiac V8 Engine Bore and Stroke Specifications

The following specifications compare the bore, stroke, main journal diameter, and connecting rod journal diameter for the most common Pontiac V8 engines. These specifications can help identify an engine and verify internal dimensions during a rebuild.

Note: Although the Pontiac 301 and 265 are genuine Pontiac V8 engines, they use a redesigned lightweight block introduced in 1977. Many of the visual identification features described above apply only to the traditional Pontiac V8 engine family (287–455).

Use the Pontiac engine code, block casting number, Partial VIN, and engine block date code together to accurately identify your engine’s original displacement, horsepower rating, production year, assembly plant, and factory application.

Pontiac V8 Engine Codes, Prefix Codes and Block Casting Numbers

For additional Pontiac engine and vehicle information, Pontiac Historical Services (PHS) provides factory documentation, billing history cards, and vehicle records for many Pontiac models. PHS is an excellent resource for verifying your Pontiac’s originality, factory options, engine information, and production history.