Engine Suffix Codes

All engines are stamped with an engine ID code, consisting of assembly plant code, production date and suffix code. The location of this code depends on the type of engine, typically as follows:
Small Block Chevy: Machined pad in front of the passenger side cylinder head. Often hidden by the alterator.
Big Block Chevy: Machined pad in front of the passenger side cylinder head or above timing chain cover.
Six Cylinder: Passenger side of the block behind the distributor.

The prefix portion of the ID code tells you the engine assembly plant code, and the engine’s assembly date (for example, 0701 = July 1st….no year is indicated). The suffix portion tells you the original application, vehicle model, engine RPO/ transmission / horsepower, etc… (for example, CTY = 1970 396 Camaro, 375 hp, 11.0:1, TH400).

The engine assembly date must precede the car build date (often by a few days), otherwise something is amiss. Some engine machining operations (decking) will obliterate the engine ID.

Engine ID Code Example: V0101CLJ - (V = Plant, 01 = Month, 01 = Day, CLJ = Engine Suffix Code)
Another example: T0830CTY – (T = Tonawanda, 08 = August, 30 = 30th day, CTY = 1970 396 Camaro, 375 hp, 11.0:1, TH400)

Code Engine Plant Code Engine Plant
F Flint (Motor) S Saginaw Service
H Hydramatic T Tonawanda
K St. Catherines, Ontario V Flint (Engine)
(McKinnon Industries Canada)
M GM of Mexico

Suffix codes are either alphabetical or alphanumeric. Select the portion of the alphabet for your code. For example, select “DTR-HQ” if you’d like to find code DZ. In some cases suffix codes are reused twice or more over time, in this event check the partial VIN code or block casting date code and then see what year the block was made to pin down what application your block was originally used in.

This list of codes is a summarization, it is not complete nor all inclusive.

Chevrolet Small Block Engine Suffix Codes

Chevrolet Big Block Engine Suffix Codes

  1. Chevrolet Big Block Engine Suffix Codes OFC-9XZ
  2. Chevrolet Big Block Engine Suffix Codes AAA-CTB
  3. Chevrolet Big Block Engine Suffix Codes CTH-IJ
  4. Chevrolet Big Block Engine Suffix Codes IK-MZ
  5. Chevrolet Big Block Engine Suffix Codes Q-YZ

Note: CODE CExxxx (counter or crate engine) was used from 1968 to current year. It represents any CID and is used to indicate this particular engine was replaced under Warranty. It is a direct replacement for the original equipment. It doesn’t indicate what the original equipment was.

VF292800 – is an example of a over the counter crate engine. “2800” is the last 4 digits of the GM part # for the crate engine assembly. The final digit could be a year code.
Another example: A Targetmaster engine (p/n 14009800) built in 1985 could have a code stamped as follows:
A0198005 (A = january, 01, 9800 = pn, 5 = 1985).

Casting Dates

Small block casting date is located on driver side rear of block on flange forward of bellhousing. Big block on the right side of engine above the oil pan rails.

Casting Date Example: E038 – (E = Month, 03 = Day, 8 = Last digit of model year (1978)).

Month: A = Jan, B = Feb, C = Mar, D = Apr, E = May, F = Jun, G = July, H = Aug, I = Sep, J = Oct, K = Nov, L = Dec

Casting Clocks

On some Saginaw blocks, intakes and exhausts a “clock” was cast into the block. The clock is a circle of 10 dots, one dot for each hour of a shift (usually 10 hour shifts). An arrow points to the beginning of the shift an another dot outside the circle indicates what time of day the cast part was made. Anyways, that’s what that circle thing is (if you happen to see it on something).

Source: http://www.nastyz28.com/decode.php#aplant

 

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Comments

  1. Adam Rapone says:

    TYT on chevy small block is a 1975 built 350 with 165hp

  2. Adam Rapone says:

    built in Flint Michigan 20th Dec. It’s a 283 from 1957 or 1965

  3. Code Year CID Vehicle HP RPO Trans Carb Comments
    TYZ 75 350 Truck 160 LS-9 Manual 4-Brl C 10 & C 20
    TYZ 76 350 Truck 165 LS-9 Manual 4-Brl C 10 & C 20
    TYZ 77 350 Truck 165 LS-9 Manual 4-Brl C 10 & C 20

  4. Code Year CID Vehicle HP RPO Trans Carb Comments
    TYT 75 350 Truck 160 LS-9 Manual 4-Brl C-20 & C-30, Van
    TYT 76 350 Truck 165 LS-9 Manual 4-Brl C-20 & C-30, Van
    TYT 77 350 Truck 165 LS-9 Manual 4-Brl C-20 & C-30, Van

  5. Code Year CID Vehicle HP RPO Trans Carb Comments
    CPY 77 305 Pontiac 145 LG-3 TH 350 2-Brl Phoenix, Ventura II
    CPY 77 305 Oldsmobile 145 LG-3 TH 350 2-Brl Omega
    CPY 77 305 Nova 145 LG-3 TH 350 2-Brl
    CPY 77 305 Chevelle 145 LG-3 TH 350 2-Brl
    CPY 77 305 Camaro 145 LG-3 TH 350 2-Brl
    CPY 77 305 Buick 145 LG-3 TH 350 2-Brl Skylark

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  13. Glen Sammons says:

    Do Anyone know what the number fro25d On a old Chevy small block v8 is?

  14. What motor do I have
    v0525tyz
    C7s192738

  15. Whats Ruiz cose?
    FO42IHC

  16. Heres a wierd one pm me the results K0716c8c