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, and the days count sequentially from then. The 1970 model year range of days is 2895 – 3259. Tables are in the factory parts catalogs, and as you noted, 3174 = April 6, 1970. Tables/charts and calculators for the dates are also available online. The following image shows the table from the 1970-1971 Parts Catalog:

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
✠ with X = 0.010″ Undersized crankshaft journals

 

[money pit]

The Chrysler 10000 day calendar is a date coding scheme. The beginning day of the first 10000 day range was Saturday July 29th, 1961, and the days count sequentially from then. The 1970 model year range of days is 2895 – 3259. Tables are in the factory parts catalogs, and as you noted, 3174 = April 6, 1970. Tables/charts and calculators for the dates are also available online. The following image shows the table from the 1970-1971 Parts Catalog:
View attachment 141288

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
✠ with X = 0.010″ Undersized crankshaft journals

Such a complex way to code the details. I'm having a problem decoding the stamping on my engine. The car was originally a 383 2 barrel. It was converted to a AAR clone by the previous owner. The 340 needs to be rebuilt so I want to be sure I have the proper year.