How to decode stamped numbers on 340 block front drivers side?

[Cudakiller70]

I could only find a place for wedge motors decoding. http://www.moparts.org/Tech/Archive/motor/36.html
Trying to figure out what I have? This block is stamped HM 340 R 36440 134.
From googling around I'm pretty sure H = 1972 but not sure on the rest?
Has anyone done this or know where to look?

[RzeroB]

"HM 340 R 3644 0134" is the engine factory build ID.

You can break it down as follows:

Model year
Engine plant
Engine displacement
Special engine information
Build date in 10,000 day calendar format (why they came up with that monster I don't know)
Number of engines built that day

So in your case it would be:

H = 1972 model year
M = Mound Road engine plant
340 = 340 CI engine
R = regular fuel (vs a "P" for premium fuel which was stamped on the higher compression 68-71 340 engines)
3644 = 20 July 1971 assembly date in 10,000 day calendar format
0134 = 134th engine assembled at the Mound Road engine plant that day

There you go! 

[Cudakiller70]

"HM 340 R 3644 0134" is the engine factory build ID.

You can break it down as follows:

Model year
Engine plant
Engine displacement
Special engine information
Build date in 10,000 day calendar format (why they came up with that monster I don't know)
Number of engines built that day

So in your case it would be:

H = 1972 model year
M = Mound Road engine plant
340 = 340 CI engine
R = regular fuel (vs a "P" for premium fuel which was stamped on the higher compression 68-71 340 engines)
3644 = 20 July 1971 assembly date in 10,000 day calendar format
0134 = 134th engine assembled at the Mound Road engine plant that day

There you go! 

Excellent Rzero! Appreciate your looking it up for me. That's the info I couldn't find and needed. 
Thank you!

[blown motor]

Where exactly are these numbers? All I have on the left side is the number 2780930-340-2 cast into the block. There are no letters.

[Cudakiller70]

Where exactly are these numbers? All I have on the left side is the number 2780930-340-2 cast into the block. There are no letters.

 On face of block, Drivers side front of block above green tape.

[7212Mopar]

"HM 340 R 3644 0134" is the engine factory build ID.

You can break it down as follows:

Model year
Engine plant
Engine displacement
Special engine information
Build date in 10,000 day calendar format (why they came up with that monster I don't know)
Number of engines built that day

So in your case it would be:

H = 1972 model year
M = Mound Road engine plant
340 = 340 CI engine
R = regular fuel (vs a "P" for premium fuel which was stamped on the higher compression 68-71 340 engines)
3644 = 20 July 1971 assembly date in 10,000 day calendar format
0134 = 134th engine assembled at the Mound Road engine plant that day

There you go! 
[/quote

HI RzeroB, mine started with CW. What will that translated to year and plant? Thanks

[7212Mopar]

Found it. It is a G and not C. 1971, Windsor

[blown motor]

Thanks Cudakiller. I never knew there was numbers there.
Mine read LM 340     400    187. It's very hard to read. Maybe if I sand the paint of it would show up better.
There is a digit between 400 and 187 but I can't make it out. Most likely 3, 5, 6, 8 or 0.
Does the L indicate 1973?

[Cudakiller70]

Thanks Cudakiller. I never knew there was numbers there.
Mine read LM 340     400    187. It's very hard to read. Maybe if I sand the paint of it would show up better.
There is a digit between 400 and 187 but I can't make it out. Most likely 3, 5, 6, 8 or 0.
Does the L indicate 1973?

For reading numbers I've had good luck doing one of two ways. First try rubbing your finger in a greasy oily spot, then rub across the numbers. 2nd way In that pick I used a single edged razor blade scrapped off the surface paint and the paint inside the stamped numbers/letters stayed making it easier to read.

 "L " I don't know 

Wonder where RzeroB and 7212Mopar looked it up

[blown motor]

I did find a listing of date codes. According to that L is 75. But mine is a 340, no longer built in 75. 

[Cudakiller70]

 :poopoke:s

I did find a listing of date codes. According to that L is 75. But mine is a 340, no longer built in 75. 

Stumbled on this, but not sure it helps.
http://moparcarparts.com/engineident

[blown motor]

Ya that's where I found it.

[Cudakiller70]

I did find a listing of date codes. According to that L is 75. But mine is a 340, no longer built in 75. 

This might be better go to your year (73 ?)codes, I'm just scratching here cause I don't know.
http://www.lhmopars.com/vin66-74.htm