Small Block Chevy Engine Block Identification

One of the easiest way to identify a Chevrolet engine is by the casting number (c/n) that is cast into the castings (not stamped).Chevy engine casting numbers has additional info including links to several sites that have casting numbers broken down to application, etc. The Chevy V8 block casting number is generally atop the transmission mounting area of the block. 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.

General block Info | Block Casting Numbers | Block Casting Date | Engine Code Stamping | Casting Clock Code
VIN Code Format | Camaro Specific Engine Codes | Small Block Suffix Codes

General Engine Block Specifications
While 6 different bore size blocks have been produced, the small block engine can be classified into 3 bore sizes and 3 main bearing sizes. 283 blocks (3.875' bore, 2.3' main), 302/327/350 blocks (4' bore, 2.3' or 2.45' mains), and 400 blocks (4.126', 2.65' mains). In 1968 the main bearing saddles were increased in size from 2.3' to 2.45'.

CID	Year	Bore	Main Cap
262	1975	3.671	2 bolt ONLY
267	1979 - 81	3.500	2 bolt ONLY
305	1976 - 96	3.736	2 bolt ONLY
307	1968 - 73	3.875	2 bolt ONLY
327	1968-69	4.001 (2.3' main)	2 bolt
350	1968-88	4.001 (2.3' main)	2 bolt
265	1994	4.001 (2.45' main)	2 bolt
302	1968-69	4.001 (2.45' main)	4 bolt
350	1968-96	4.001 (2.45' main)	4 bolt
400	1970-72	4.126 (2.65' main)	4 bolt
400	1973-80	4.126 (2.65' main)	2 bolt

Notes: 2 bolt ONLY means what it says. You will NOT find a 4 bolt 305 block (made by the factory). Period. Otherwise 2 or 4 bolt can mean either design...

Engine Code Stamping Numbers
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. 6 cylinder engines are stamped on the passenger side of the block behind the distributor.
Click here for Chevy Engine Code Listings

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)

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

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).

Camaro Engine Code Stamping Numbers
Dropbox contains Camaro engine suffix codes for year selected.