Chevrolet Small V-8 Cylinder Block Casting Numbers 1955-1985 These listings are always a work-in-progress. If you have any documented info that can be added to these pages.

Here's a Chevy motor question that comes up all the time - 216 or early 235? Guys are always posting this question. How to identify this early 235 High Torque, digging for numbers and measuring stuff. Attached is a photo of my 1946 High Torque 235 pan which plainly has the number '235' stamped on the right side, big as day. Here's an engine. I can see the partial VIN (13N132794) and the engine code (V0112CLJ). Quickly from the partial vin I know this is a Chevy (1) 1973 model year (3) built in Norwood Ohio (N). 132794 is the unique vehicle serial number (to match against vehicle VIN). I know Norwood built Camaros - among other things.

Chevy Small Block V8 Engine Identification

General Decoding Information
This topic can be somewhat confusing, especially with the amount of information available and the interpretation of it. The primary pieces of information you'll decode are the;

1. Engine Code and
2. Partial VIN.
3. Casting Date.
4. Casting Number.

The engine code and partial vin # will accurately nail down whatever the thing is rather quickly, and the other information will fall into line with that.

'Numbers Matching'
This is my opinion, and the generally accepted norm:
When people say 'It's numbers matching' - what they mean is the engine (or other component, i.e the transmission) can be MATCHED to the vehicle it was originally used in. This match is done via the PARTIAL VIN stamp on the component. The partial VIN will match the vehicles VIN. If it does - it's 'numbers matching', otherwise - it's not. done. end of story.
Some folks use these terms loosely, or will say 'numbers correct' or something to that effect. But numbers correct is not numbers matching. Again, it either matches or it doesn't. If it doesn't match - is it correct?
Numbers matching is important when you're trying to decode a Z28 or Super Sport where the VIN won't identify the vehicle as such. You need to decode the engine and see if it matches the vehicle, and if the code signifies Z28 or SS equipment.
Lastly, in extreme cases, you'll want to verify the numbers stamped onto the component were the ones stamped into it originally and aren't restamped.
The point of this page is to help you figure out how to decode stuff.

1. ENGINE CODE STAMPING NUMBER

All engines are stamped with an engine ID code, consisting of assembly plant code, production date and suffix code. V8 codes are stamped on a pad just forward of the right side (passenger) cylinder head.

The engine date must precede the car build date, 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)

Engine Plant Code

Engine Suffix Code

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.

OHV

Small Block Engine Suffix Code Menu
3N - CDR | CE - CMJ | CMK - CUD | CUF - DTM |DTR - HQ | HR - TBS | TBT - TJS | TJT - TXB | TXC - UTT | UTU - ZY

Big Block Engine Suffix Code Menu
0FC - 9XZ | AAA - CTB | CTH - IJ | IK - MZ | 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).

2. VIN CODE

VIN Code Format
The vin code format is stamped onto most engines. The format consists of divisional identification number, model year, assembly plant designation and vehicle serial or sequence number.
In 68-69 model cars, the serial (VIN) number of the car the engine was installed in is stamped next to, or under the engine code ID.
Starting in 1970, the serial number is stamped either above the oil filter, somewhere on the block pad (in front of the cylinder head), or on the transmission flange somewhere. Chevrolet issued technical service bulletins to indicate which engines were to recieve a vin stamp, so who knows what could have happend (or not happened).

A Stovebolt Tech Tip! Identifying Your 216 / 235 / 261 Engine

VIN code format Example: 13N100001
(1 = Chevrolet, 3 = 1973, N = Norwood, 100001 = Production sequence of vehicle VIN)

Assembly Plants

In 1972, plant codes changed to reflect the VIN code. For example, 'NOR' = Norwood before 1972. In 1972 and on, it was simply 'N'.

3. CASTING DATE

Casting Clock
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).

See Full List On 1954advance-design.com

Casting Date
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

4. ENGINE BLOCK CASTING NUMBER

Notes (for below): 'High Power' is the maximum rate HP this block was used for, 'Low Power' is the lowest rated horsepower RPO engine the block was used in. 'Main Caps' is the number of bolts holding the cap. A 'two-bolt' main, or a four-bolt main. Four bolt main blocks are desirable in high performance applications because the extra strength of the additional bolts keeps the bottom end rigid and less prone to failure. However, a properly prepared 2 bolt main engine will work just fine (often times you'll lose a rod bolt before you break a crank because it's 'only' a 2 bolt main).

General Engine Block Specifications

The Casting Numbers to the right are found just below and to the right of the Distributor on the passenger side. They are notoriously very hard to read and often people make the mistake of thinking a '3' is an '8'. Clean the area thoroughly and use a nice bright flashlight. This is usually a 7 digit number and each letter/number is about 1/2' tall. A little engine degreaser and a wire brush often makes this job easier.

The next numbers we need are the ones just below the Starter on the passenger side. This one will have a CONveyor Number and beside that a usually four digit letter/number combination separated like this: X XX X. For example, the first X will be a Letter from A through L. A = January through L = December. The center two digits are the day of the month. The final digit is the year the engine was made WITHIN the years that you narrowed it down to when you deciphered the Casting Numbers to the right.

The next set of numbers you will find helpful are on the flat part of the Distributor Deck. This machined flat area has serial numbers stamped into it. If you have looked very carefully and find no numbers there, chances are your block is classified as a Replacement Block and will have no numbers stamped on that deck. The numbers you are looking for are stamped (about 1/4' high) and usually a Letter followed by three Numbers and ending in another Letter (or two). The first letter is almost always F since most GM engines were made in Flint, Michigan. The following numbers are the month first followed by the day of the month. The trailing letters denote what the engine was installed in. The possible Letters for the last ones are explained in the chart below.