73 340 engine build date

[mrob]

I have a question about the engine build date on a 73 340 that I'm thinking about buying. The casting date on the block is 9 26 72, but the codes on the front of the block (below the LH head) are: 3M 340 0302 0802.
AFAIK, this decodes to: 73 340 built at the Mound Rd. plant on 03/02, engine seq. number 0802.
So here's what I'm wondering:
1) Is the 0302 date a calendar date (i.e., March 02) or is it a julian date?
2) If the date is a calendar date, why is it so much later than the casting date? I always thought that engine build dates were much closer to the casting dates.

[Alaskan_TA]

Can you re-check the numbers? The  0302  number most likely would start with a 4.

If you can get a clear close-up photo that would be even better.

[vinb]

Speaking of '73's..

I have a '73 340 date on side is 2/9/73..
                                  front is 06068337...?

It was suppose to come out of a Road Runner...

[Alaskan_TA]

06068337 - is missing some numbers / spaces?


If it has a partial VIN on it, list that, It will narrow down what it came out of some.


Photos for these type of numbers are the best way to go.   

[vinb]

  3M340    06068337

3B523670 vin...

That is all I see...

[Alaskan_TA]

The first 3 is likely a J.

The 06068337 digits do not compute for the model year.

The VIN is missing a digit also?

Once again, photos are the way to go. If the factory mis-stamped it, then at least I can see what you see instead of trying to guess. 

If it does have a B as the second digit, then it it from a Challenger, Barracuda, Duster or Dart Sport since those are the only 4 cars they made at Hamtramck in 1973 with 340s.

[vinb]

Thanks Barry,
I'll clean it off tomorrow and take a couple of photos....

[mrob]

I did some more research and now I think that the 0302 code is a calendar date which means that the block was cast on 9/26/72 but assembled on 3/2/73.
Vinb posted a similar situation where his block was cast on 2/9/73, but assembled on 6/6/73.
What I find interesting is the lag time between the assembly date and the casting date. In Vinb's case the block sat around for 4 months until it was assembled and put in the car. I was always under the impression that the two dates were much closer.

[moper]

You can never really tell for sure. It could be a simple matter of lagging sales and no need for them. Or a lost shipment that was found. 383s were sometimes left for months too, which really seemed strange to me.

[mrob]

Just an FYI to anyone interested in the varying ways that 340's were stamped:

http://www.yearone.com/pco/1_0309/t1.asp?page=10

You'll see that on some small blocks, the assembly date was in mm dd format and the year was in the year code. The assembly date was not always taken from the 10000 day calendar.

[Alaskan_TA]

From the 1973 TSB on engine stampings;

http://www.hamtramck-historical.com/images/TSBs/1973/25-01-73C%20page6.jpg

I have not seen a 340 date (yet) that is not in the 10,000 day calender format.

I would still like to see photos & know the VIN also.

[mrob]

Just for the sake of discussion, take a look at this ebay auction:

http://cgi.ebay.com/ebaymotors/Mopar-Dodge-Plymouth-340-4-Barrel-Engine-LOOK_W0QQcmdZViewItemQQ_trksidZp3286Q2ec0Q2em14QQhashZitem35a3e5d0c2QQitemZ230383014082QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

The seller lists the codes as follows:

Drivers Side Front: 3M 340 03268002

Casting # on Block: 2780930-340-5

Heads: 3571587 0343 360

Look at the date format of the stamping from the front of the block:

3M 340 03268002

3 - 1973
M - Mound Rd. plant
0326 - This can't be a 10000 day date. In 73, the dates were in the 4000's, so a calendar date of 3/26 makes more sense to me.
8002 - seq. no. of block

I'm also interested in seeing Vinb's pics.

[vinb]

Barry I sent the photos to your e-mail.....
mrob send me a PM with your e-mail and I'll send you them too...
Ok, here is what I got..

2/9/73

2780930-340-6   4

3B523670

3M340     06068337

Intake 4/27/73

Heads are 587's....

[Alaskan_TA]

Thanks Vinny!

Very strange, I can not believe they were making over 8000 engines a day, so I am wondering if they changed the whole numbering system at some point now.....

I'll do a little digging. 

[vinb]

Did you get the photos?

I sent them 800x600

I could send them 3072x2740

That is a engine I bought from a friend and may build a stroker from that or sell it to one of my Stocker buddies..