Steps to identify a B or RB engine through the numbers stamped on the machined pad at the front of the engine.
On B engines (350-361-383-400 ci), there is a pad on the right front of the engine, below the distributor, on the same plane as the deck. On RB engines (383, 413, 426, 440 ci), there is a horizontal pad on the left front of the engine, just in front of the valley. These pads contain stampings that will quickly identify an engine and usually tell you a little about it.
The stampings on the top of the block will look something like this:
C H 426 B
8-3-32
These particular markings follow this format:
Series / Hemispherical / CID / B-body
Month-Day-The Number Engine Built This Day
Another example, for a 1965 race Hemi
A H-426 hc
8-1-01
And, the wedge engine will have something like:
A-413-8-1
These marking are noted below.
SERIES:
S = 1962
T = 1963
V = 1964
A = 1965
B = 1966
C = 1967
D = 1968
E = 1969
F = 1970
G = 1971
H = 1972
J = 1973
4T = 1974
5T = 1975
6T = 1976
7T = 1977
8T = 1978
OTHER STAMPINGS:
Diamond = 0.008-in. oversize tappets
Maltese Cross = 0.001-in. undersized crankshaft
Maltese Cross and an X = 0.010 undersized crankshaft
A = 0.020-in. oversized cylinder bore
B = 0.010-in. undersized main and rod bearings
E = cast crankshaft
H = standard 4bbl
HP = high performance
HC = high compression
LC = low compression
MP = maximum performance
O.S. = 0.005 oversized valve stems
P = premium fuel recommended
R = regular grade fuel may be used
S = special engine
WT or TW = water test
X = oversized valve guides
ASSEMBLY PLANTS:
K = Toluca
PT = Trenton
M = Mound Road
T = Trenton (400 and 440 only)
MV or MN = Marysville
The stamping on the bottom of the block will be the formal serial number for that block and read similar to the following:
9-10-68 PT38326010001.
These numbers are decoded as follows:
A. The first numbers are the date of the stamping (9-10-68)
B. The next letters indicate the engine assembly plant- in the case of our example, Trenton.
C. The next three digits indicate cubic inch displacement: 383
D. The next four digits (2601) are from the 10,000 day calendar: 2601 = Sept 10, 1968.
E. The final four numbers (0001) show that this was the first engine assembled that day.