Many people ask how do I find out what a small block engine is? You can find out alot about it if you know where to look....

The first question is: "How do I know what size it is?" That can be easily found out by looking at the driver's side of the block (the one without the oil filter). The casting number is found on the driver's side (left side) of the block as shown here:

360 Lt Side B01 B3.jpg

Here is a close up of the casting number. You can see that the engine size is cast into the block at the end of the casting number. This is one for a 360:

360 Lt Side B02 B3.jpg

Now you want to go to the passenger side (right side) of the block where the oil filter mounting pad is for more juicy info. Here is what you are looking for in the picture.

A. This is the VIN pad. This is where the last 8 digits for the vehicle's VIN number that is usually found on the dash board. You can decipher what model year vehicle the engine came in, and the assembly plant that the vehicle was made in. The last 6 digits are the sequence number from the VIN found on the dash board. This number needs to match the last 8 digits of your VIN plate on the dash to be a "Numbers Matching" engine for your car:

B. This is the casting date for the block with the clock to show what time it was cast.

C. This is the shift that the block was cast on at the casting factory, D is for day shift, N is for night shift:

360 Rt Side B02 B2.jpg

Here is a close up of the casting date and shift on the side of the block:

360 Rt Side B05 B2.jpg

Here is a close up of the VIN pad. This is where the last 8 digits for the VIN number for the vehicle that it came from the factory. The first digit is the model year that the vehicle that the engine originally came in. The second digit will tell you what vehicle assembly plant built the vehicle. The last 6 digits are the sequence number for the VIN. These can be hard to see as they get covered with paint, grease, and grime, so you may need to do some scraping to find it and read it:

360 Rt Side B04 B2.jpg

Here's a chart to decode the whole vehicle VIN number:

VIN ID A01 B2.jpg

On the front of the block under the driver's side (left side) head, you will find another batch of numbers stamped into the block. This is the information from the engine assembly plant. Like the VIN pad above, it can be covered in paint, grease, and grime; so you may have to do some scraping and cleaning to see it.

360 Front B01 B2.jpg

Here's a close up of where you will find the information:

360 Front B02 B2.jpg

Here's the chart to decode the engine plant information:

Engine ID A01 B2.jpg

Good luck and have fun!

Here's some additional info that Rocky_JS added to help us:

Some additional stuff I have saved. These are the special engine assembly codes.

T = Truck
R = Regular Fuel
P = Premium Fuel
LC = Low Compression
HC = High Compression
MP = Maximum Performance
HP, HP2 = High Performance, HP2 = 2nd shift
X = .001" Undersize Crank
X = .U10" Undersize Crank
Diamond = .008" Oversize Tappets
OS = .005" Oversized Valve Guides
X = Oversize Valve Guides
S = Special Engine (possibly warranty)
SP = Special Engine TA340 or police and seen on big block a-body engine also
WT = Water Tested
H = Hemi before displacement ex. H426
A = .02U" Oversize Cylinder Bore
B = .010" Undersize Main and Rod Bearings
E = Cast Crank
H = Standard 4-bbl V8

With some of the over/undersized components you may see a 4 or 4I or 4E. These will equate to cyl number 4 and/or 4 Intake or Exhaust. Sometimes not noted at all as to which cyl has oversized lifter etc.

Model Year
the following is a list of letter codes and their corresponding years. The year always precedes the engine displacement. Ex: C273 = 1967 273 engine.
P = 1960
R = 1961
S = 1962
T = 1963
V = 1964
A = 1965
B = 1966
C = 1967
D = 1968
E = 1969
F = 1970
G = 1971
H = 1972
J = 1973
K or 4 = 1974
L or 5 = 1975
M or 6 = 1976
N or 7 = 1977

Engine Assembly Plant Codes
K = Toluca
M or PM = Mound Rd.
MV or MN = Marysville
T or PT = Trenton
W = Windsor