Chevrolet Engine Identification Guide: Casting Numbers and Engine Codes
There’s a special kind of satisfaction that comes from knowing exactly what’s sitting between the fenders of your Chevy—whether you’re verifying a numbers-matching classic or figuring out what’s under the hood of a project truck.
You’ve just bought a vintage Camaro and want to confirm it’s got the original 302, or maybe you’re at a swap meet eyeing a bare block and need to know what you’re really buying. The numbers on that lump of iron tell a complete story—displacement, horsepower, original application, and even the day it was cast. Let’s decode that story together.
TL;DR (Too Long; Didn’t Read)
Your Chevy engine has two critical identification systems. The casting number is raised metal on the block itself (found at the rear of the block behind the intake manifold) and tells you displacement, main cap bolt count, and approximate year range . The engine ID code is a stamped number on a machined pad (usually at the front passenger side of the block) that reveals assembly plant, build date, and a suffix code identifying the original application and horsepower . On vehicles from about 1968 onward, you’ll also find a partial VIN stamped near the engine code to confirm originality . The eighth digit of your Chevy’s VIN can identify modern LT engines and EcoTec3 truck engines . Both numbers are needed for complete identification.
Casting Numbers vs. Stamped Codes: What’s the Difference?
Before we get into locations, let’s clear up the two systems Chevy uses. They serve different purposes.
The casting number is raised metal that’s part of the block itself, created when the molten iron was poured into the mold . This number tells you what the block was designed to be—displacement, whether it’s a 2-bolt or 4-bolt main, and its original casting year or year range. It cannot be altered without grinding it off.
The engine ID code (also called the stamp code or suffix code) is stamped into a machined pad after casting . This tells you where the engine was assembled, on what date, and what vehicle it was originally installed in. This is the code that lets you confirm whether that 350 really came from a 1969 Camaro or a station wagon.
Here’s the thing about Chevy engine identification—both numbers must match your expectations. A casting number for a 350 block doesn’t guarantee it’s a high-performance engine. The suffix code tells you how it left the factory.
Where to Find Your Chevy Engine Numbers
Location depends on whether you’re dealing with a small-block or big-block.
Small-Block Chevy V8
Casting Number Location: Look at the rear of the block where the transmission bellhousing bolts up. It’s on the driver’s side, on the top ledge just behind the intake manifold . You’ll need a good flashlight, and cleaning off years of grime helps. On some blocks, you might find it on the passenger side .
Engine ID Code Location: This is stamped on a machined flat pad just in front of the passenger-side cylinder head . The alternator often obscures it, so you may need to move things aside. On some newer engines, it’s on a pad above the timing chain cover .
Big-Block Chevy V8
Casting Number Location: Similar to small-blocks—on the rear ledge of the block where the transmission attaches .
Engine ID Code Location: You’ll find it on the front passenger side of the block in the same general area . Some big-blocks also have it above the timing chain cover.
Inline Six-Cylinders
The casting number sits on the passenger side of the block, often hidden by the starter motor . The stamped engine code is at the base of the distributor .
Decoding the Casting Number
The casting number is typically six to eight digits and contains no letters . Here are some examples to show you what to look for.
Small-Block Chevy (SBC) Casting Numbers
| Casting Number | Displacement | Years | Notes |
|---|---|---|---|
| 3970010 | 350 | 1969-1980 | One of the most common, 2 or 4-bolt mains |
| 3932388 | 350 | 1969 | 2 or 4-bolt |
| 3892657 | 302 | 1967 | Small-journal, Camaro Z28, rare |
| 3914678 | 302 | 1968 | Large-journal, Camaro Z28 |
| 3956618 | 302 | 1969 | 4-bolt, Camaro Z28 |
| 3782870 | 327 | 1962-1967 | 2-bolt |
| 3858618 | 350 | 1968-1976 | 2-bolt |
| 14010207 | 350 | 1980-1985 | 2 or 4-bolt |
| 14093638 | 350 | 1987-1995 | Roller or flat-tappet cam, 1-piece rear seal |
| 10243880 | 350 | 1995-1999 | ZZ4 crate, roller cam, 1-piece rear seal |
Big-Block Chevy (BBC) Casting Numbers
| Casting Number | Displacement | Years | Notes |
|---|---|---|---|
| 3963512 | 427/454 | 1969-1976 | 2 or 4-bolt |
| 3855961 | 396 | 1965-1966 | 2 or 4-bolt |
| 3999289 | 454 | 1972-1979 | 2 or 4-bolt |
| 10237297 | 454 | 1996-up | Vortec 7400, Gen.VI |
| 12550313 | 454 | 1991-up | Gen.V crate motor |
Block Casting Date Codes
Right next to the casting number, you’ll usually find the casting date code . This is a letter followed by numbers:
- Letter = Month: A=January, B=February, C=March, D=April, E=May, F=June, G=July, H=August, I=September, J=October, K=November, L=December
- Numbers = Day and Year: For example, “I 9 57” means September 9, 1957 . “F 21 2” means June 21, 1962 .
The casting date should always be before the engine assembly date. Cast iron needs time to cool and be machined, so if your assembly date is before your casting date, something’s off.
Decoding the Engine ID Code (Stamped Pad)
The stamped code follows a consistent format :
Example: V 08 01 CML
| Part | Meaning |
|---|---|
| V | Assembly plant (Flint, Michigan) |
| 08 | Month of assembly (August) |
| 01 | Day of assembly (1st) |
| CML | Suffix code (original application) |
Assembly Plant Codes
| Code | Plant |
|---|---|
| F | Flint, Michigan |
| V | Flint Engine (also used) |
| T | Tonawanda, New York |
| K | GM of Canada |
| M | GM of Mexico |
Engine Suffix Codes (Examples)
The suffix tells you what the engine was originally installed in. Many suffix codes were reused across different years, so you’ll need the casting date to narrow it down .
| Suffix | Application |
|---|---|
| MO | 302, 1967-1968 Camaro Z28 (small-journal for 1967, large-journal for 1968) |
| MP | 302, 1967 with A.I.R. emissions |
| DZ | 302, 1969 Camaro Z28 (the legendary DZ302) |
| CML | 1975 Camaro 155HP or 1980 Z28 190HP (possible codes, check partial VIN for year) |
Using the VIN to Identify Modern Engines
For newer Chevrolets, the eighth digit of the VIN is your shortcut . This is especially useful for the Gen V LT engines and EcoTec3 truck engines.
Gen V LT (Car Engines)
| 8th VIN Digit | RPO Code | Displacement | Common Name |
|---|---|---|---|
| 7 | LT1 | 6.2L | LT1 |
| 6 | LT4 | 6.2L | LT4 (supercharged) |
EcoTec3 (Truck Engines)
| 8th VIN Digit | RPO Code | Displacement | Common Name |
|---|---|---|---|
| C | L83 | 5.3L | EcoTec3 5.3L |
| J | L86 | 6.2L | EcoTec3 6.2L |
| R | L8B | 5.3L | EcoTec3 with eAssist |
Partial VIN Stamping: Confirming Originality
From about 1968 onward, Chevrolet stamped a partial VIN on the engine block near the engine ID code . This is the factory’s way of saying “this engine came in this specific vehicle.”
This partial VIN includes the division number, model year, assembly plant, and vehicle build sequence number . If you’re restoring a numbers-matching car and the partial VIN doesn’t match the car’s VIN, the engine has been swapped at some point.
When checking a classic car, the partial VIN stamping is your best evidence of originality. But be careful—counterfeit stampings exist, and the machining marks around the pad can reveal a re-stamp.
FAQ: Your Top Chevy Engine ID Questions Answered
Q: Where is the casting number located on a Chevy small-block?
A: At the rear of the block on the driver’s side, on the ledge just behind the intake manifold where the transmission bolts up .
Q: What’s the difference between the casting number and the stamp code?
A: The casting number is raised metal from when the block was cast and identifies displacement and main cap design. The stamp code is engraved on a machined pad and tells you assembly plant, build date, and original application .
Q: What does the suffix code tell me?
A: It tells you the original vehicle application, horsepower, and transmission the engine was originally mated to .
Q: How do I identify a 1969 DZ302?
A: Look for casting number 3932386, 3956618, 3932388, or 3970010, with suffix code “DZ” and the correct partial VIN .
Q: Can I identify a modern LT engine from the VIN?
A: Yes. The 8th digit of the VIN indicates the engine. For car LT engines, 7 = LT1 (6.2L), 6 = LT4 (supercharged). For truck EcoTec3, C = L83 (5.3L), J = L86 (6.2L) .
Q: How do I decode the casting date?
A: The letter is the month (A=January), the numbers are the day and last digit of the year. For example, F 21 2 = June 21, 1962 .
Q: Will a CE prefix on the stamp code tell me anything?
A: CE stands for “Chevrolet Engine” and indicates a service replacement or crate engine, not original factory installation .
References
Chevrolet Engine Identification Resources:
