Somethings not right

[Amata Bene]

Like I've said in other posts. I'm new. I'm sure this is well worn out topic. It is an engine code topic, with a twist though. Here are all the numbers I have gotten off the block, both castings and stamped.

CASTING # L. Side - 2780930-340-5 = 340 SB Factory part #
CASTING # R. Side - 1-18-71 = Forging Date January 18, 1971 (there is also a large 4 and smaller 0 N towards the rear of the block past the MM ?)
STAMPED # Lower R. Side - 2B316391 = Last 8 Digits of V.I.N. (above oil pan)
This is the kicker:
STAMPED # Front L. Under Cylinder Head - MH 340R 38480155 (or) 88480155 = Mound Road assembly plant H4barrel 340Regular fuel 38480155 (or) 88480155 Machine date and unit.

If I understand all that I have researched that tells me this was the 155th block machined that day of 1968.
Now... What day is that? The 384th day? Hmm, that don't work. Maybe the 884th day. Somethings not right.

I know it is man made so the possibility of human error in plausible. Has anyone ever seen or run into this before?

 

[RemCharger]

It's a cast 71, 72 model year engine
If that's factory blue, it reaffirms that.
3848 might be the Julian #.

 

[Amata Bene]

It's a cast 71, 72 model year engine
If that's factory blue, it reaffirms that.
3848 might be the Julian #.

That's where I end up also. The stamped # under the head is throwing for a loop. Where can I find this Julian chart. Been scratching my head for a minute now. As far as factory blue, your guess is as good as anybody's. Orange paint under a lot of what I've touched so far. It has been around for 52 (?) years. Starting to find all sorts of hidden secrets. Just need to get it running well enough to make it through the summer and keep the Missis happy. She knows I will tear it completely down eventually.

 

[Amata Bene]

It's a cast 71, 72 model year engine
If that's factory blue, it reaffirms that.
3848 might be the Julian #.

Wait, the Julian code is what I been looking at. It only goes to 365. I need to find a 10,000 day chart. That's where I screwed up I bet.

 

[RemCharger]

Wait, the Julian code is what I been looking at. It only goes to 365. I need to find a 10,000 day chart. That's where I screwed up I bet.

Is there a reason you need to know the exact day it was built by the 10,000 day calender?

 

[RemCharger]

Feb 9 1972

 

[kiwigtx]

Is there a reason you need to know the exact day it was built by the 10,000 day calender?

Needs to track down the guy who assembled the engine to ask what he had in his sandwiches that day.

 

[Amata Bene]

Is there a reason you need to know the exact day it was built by the 10,000 day calender?

You are correct, Feb. 9, 1972. This is one of the easiest mopar calendrer I've found 10,000 Day Calendar & Date Codes There are a couple reasons. One being that in early production 72 they went from a forged crankshaft to a cast crank. That production # change was HM3403911800 . After that they were fitted with a cast crank. (That is according to Paul Herd in the "Used Parts Buyers Guide Road Runner and GTX") Just a better starting point in my opinion. If it's in good shape. I believe mine is, just sorting out some fuel and ignition issues. I hope.

 

[RemCharger]

You are correct, Feb. 9, 1972. This is one of the easiest mopar calendrer I've found 10,000 Day Calendar & Date Codes There are a couple reasons. One being that in early production 72 they went from a forged crankshaft to a cast crank. That production # change was HM3403911800 . After that they were fitted with a cast crank. (That is according to Paul Herd in the "Used Parts Buyers Guide Road Runner and GTX") Just a better starting point in my opinion. If it's in good shape. I believe mine is, just sorting out some fuel and ignition issues. I hope.

View attachment 1688665

Well that's good news
You can also confirm by seeing if it's a neutral balance balancer

 

[Amata Bene]

Well that's good news
You can also confirm by seeing if it's a neutral balance balancer

Yep. Been checking that out also. The face kinda resembles the liquid balancer I have on (can I speak of GM products on here) 327. Dose it count if it's in a JEEP. AMC did use Chrysler products. All I have is a part # and haven't been able to find a match yet. 83184 354-1 see if anyone can tell me. I can find steel fabrication supplies and material all day and not to bad at HD parts. I haven't played on the automotive playground for quite a while.