• Chevy Six-Cylinder Engine Identification It Still Runs
• How To Identify A Chevy Engine By Numbers It Still Runs
• Gm 235 Engine For Sale
• Chevrolet Straight-6 Engine - Wikipedia

How to decode the number on a chev inline 6 engine for the year it was made - Answered by a verified Chevy Mechanic. 378307 Chevrolet 60-62 235. Could you post the complete engine number with any letters that is on the flat spot next to the distributor? If so I can most likely tell you exactly what you have. Chevy started making 235's in '41 and they were almost identical in looks to the 216 until '54. So the serial number is one of the factors in naming this thing.

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.

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).

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).

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

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 Engine Code and Partial VIN. You can decode the casting number. And you can check dates.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.If you already know what you're doing, Chevy Engine Codes are listed down below.

Let's decode something real quick like, you can read the details further down below:

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. So I'm dealing with something from a 1973 Camaro.
Now to the engine code.
V0112 (flint, january 12th)
CLJ in 1973 is a 245 horsepower 350 used in a Z28 Camaro mated to a manual transmission.
Knowing this, I can conclude the original vehicles VIN is or was 1Q87T3N132794.
If that happens to be the vehicle this engine is currently sitting in they 'match'.
I'm Done.I can GUESS the casting # is 3970010 and check casting dates, etc.. but using these 2 things, I already know EXACTLY what this was.

Here's another:
10S437638 & V0312CTG.
1970.. S.. St. Louis (built Vettes & Impalas). 4xxx is the Corvette Range. Yikes.
CTG - in 1970.. RPO ZQ3, 300hp 350 in a Corvette.
.. and the Casting # is.. 3970010.

My point here I guess is.. trying to decode '3970010' is almost pointless. It's a 350.If you're trying to buy a 350 and you see this thing laying on the ground, then there it is. But if you want to know EXACTLY what the thing is - you need more than the casting #. Download onyx for mac 10.6 8. Once you identify something - like the above vette block, then you can conclude whatother pieces and parts should have been on it, and check those casting #'s. And/or - you can check dates to make sure everything came together when original.

ONE NOTE: Casting #'s will trump the code on a descrepancy. Take the above CLJ example. In 1987 CLJ is a 305 L69 in a monte carlo, or in 1971 it's a 400 from amonte carlo. So when the arguement over 305, 350 or 400 comes up.. now you look at the casting #. 3970010.. bang, it's a 350. That eliminates the 400 and 305 possibilities.

As you can see - codes are reused and/or they span years. This is why I looked at the VIN code 1st. 1973 - eliminates every other possiblity. Everything else lines upand there's no confusion.

Chevy Six-Cylinder Engine Identification It Still Runs

Engine Code Stamping Numbers
All engines are stamped with an engine ID code, consisting of assembly plant code, productiondate 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 assemblydate (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)

VIN Code Format
The vin code format is stamped onto most engines. The format consists of divisional identificationnumber, 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 stampednext to, or under the engine code ID.
Starting in 1970, the serial number is stamped either above the oil filter, somewhere on the blockpad (in front of the cylinder head), or on the transmission flange somewhere. Chevrolet issuedtechnical service bulletins to indicate which engines were to recieve a vin stamp, so who knows whatcould have happend (or not happened).

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

For a list of assembly plants, clickhere.

Suffix Portion of Chevy Engine 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.

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 digitsof 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 stampedas follows:
A0198005 (A = january, 01, 9800 = pn, 5 = 1985).

Here's something secret I've been working on since 2005.

'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 matchesor 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 engineand 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 article is to help you figure out how to decode stuff.

What good is knowing the transmission? MT (or Manual transmission) IMPLIES - the boss (or the pivot itself) for the clutch Z-bar is present and threaded and the crankshaft can accomodate a pilot bearing. Good news is 99.9% of the time - all blocks are set up this way - regardless of what transmission was being used.

How To Identify A Chevy Engine By Numbers It Still Runs

Hey man - is this a 4 bolt main?
I have no idea.. drilling the holes is a machining operation. It can be done on any 3970010 (or other) block. 99% of the time, the casting # won't indicate anything.HOWEVER - the engine code MAY HINT at this fact. Take a truck 350. If it codes out as a 1/2 ton application - we can bet money it's only a 2 bolt. but if it's a 3/4 or 1ton application, or some high powered application, you can ASSUME it might just be a 4 bolt main. Both of the above 350 examples are 4 bolt mains due to the application.The only guarantee is to take off the pan and look.

Gm 235 Engine For Sale

What's this A/F/X stuff?
This is the GM body designation. All these are identified here.Quickly, A = Chevelle, F = Camaro, X = Nova. If you're looking at the engine code - this is already known. If you're looking at the casting # information and it mentions3970010 'A/F/X/Y/B'.. basically this means 'it's used in everything', whereas if it simply states 'Y'.. this means corvette.

Chevrolet Straight-6 Engine - Wikipedia