Engine Build Date

[money pit]

I have a 340 engine. I'm trying to determine what year the engine is. I located the stamped info at the base of the head on the driver's side. I have looked on different threads that explain the stampings. I don't understand what they mean about a 10,000 day calendar, when they talk about the manufactured date of the engine. For example, 3174 means April 6, 1970, based on a 10,000 day calendar.

 

[Vaanth]

I have a 340 engine. I'm trying to determine what year the engine is. I located the stamped info at the base of the head on the driver's side. I have looked on different threads that explain the stampings. I don't understand what they mean about a 10,000 day calendar, when they talk about the manufactured date of the engine. For example, 3174 means April 6, 1970, based on a 10,000 day calendar.

The Chrysler 10000 day calendar is a date coding scheme. The beginning day of the first 10000 day range was Saturday July 29th, 1961. The 1970 model year range 2895 – 3259. Charts and calculators for the dates are available online, and as you noted, 3174 = April 6, 1970.

The information on the front block edge below the left cylinder head identifies build information for the engine. The following example shows a breakdown of this information:

FM340 P 3174 0450

Where:

F = the model year, with F denoting 1970
M = the build plant, with H denoting the Mound road plant
340 = the displacement, 340 cubic inches
P = Premium fuel required
3174 = the build date, specifically, April 6, 1970
0450 = the sequential number of the engines built that day, specifically, the 450th engine


The following are listings of general codes for all engines, but not necessarily all codes:

Model Years:
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, Mexico
M or PM= Mound Road, Detroit, Michigan
MN, NM or MV = Marysville, Michigan
T or PT = Trenton, Michigan
W = Windsor, Ontario

Detail Codes:
NOTE: The following varies in some years and/or applications, and combinations or specifics.
A = 0.020″ Oversized cylinder bores
B = 0.010″ Undersized main & rod journals
C = Special crankshaft & pistons
E = Cast iron crankshaft
H = Standard four barrel carburetor
H = Hemi when before displacement, ex. H426
HP = High Performance
LC = Low Compression
HC = High Compression
M = 0.001" undersize main bearing journals
MP = Maximum Performance
MX = All main journals .0010" undersized
OS = 0.005″ oversized valve guides/stems
P = Premium fuel
R = Regular fuel
RX = All rod journals 0.010" undersized
S = Service engine (found on warranty blocks)
SP = Special engine, (ex. T/A 340)
T = Truck
WT or TW = Water Tested
X = 0.010" Undersize crankshaft journals
2 = Second shift
3 = Special high performance
♦ = 0.008″ Oversized tappets
✠ = 0.001″ Undersized crankshaft journals
✠+X = 0.010″ Undersized crankshaft journals