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Assuming "S DD M Y" format of the block date code:

S = Shift or Batch. A=first, B=second etc.
DD = one or two digit day-in-month
M=Month letter, see note below
Y=Year digit

So far, we have found photos/details of AEG312 blocks with all letters A through M except E,I.

I suspect letter "I" is skipped, so the resulting table would be:

A Jan
B Feb
C Mar
D Apr
E May
F June
G July
H Aug
J Sept
K Oct
L Nov
M Dec

Props to Paul Harris [TECH396] for the groundwork he did identifying sequences on other marques.

Note that not all AEG312 blocks have this date code. Some earlier thin flange have just the MOWOG casting mark. On thick flange blocks, the date code position is slightly offset due to casting reliefs for the horizontal oil gallery. Later blocks also have a screw head indentation as part of the casting insert.

Nothing out of the ordinary from me or mine.

Thin flange, 9FXEY-523xx, ex police April 1969.

I understand that early blocks have the code on the front of the block, not the rear and is in a slightly different format ...

HI
I have a block (with No engine No', as it has been bored) with this set of code No's in the back,

D 21 J 6 with Mowog below it and it is a AEG312 under the oil gallery, also the engine size tag is missing

would this work out to be ;

Shift "D" 4th
Day 21
Month Sept
Year 1966

one other thing is the block is Blue/Gold/Green with a Red top coat, ?

regards mike

Don’t know about the ‘D’ but the day was a Wednesday.

Terrapin-52 wrote: ↑Mon May 24, 2021 8:25 am HI
I have a block (with No engine No', as it has been bored) with this set of code No's in the back,

D 21 J 6 with Mowog below it and it is a AEG312 under the oil gallery, also the engine size tag is missing

would this work out to be ;

Shift "D" 4th
Day 21
Month Sept
Year 1966

one other thing is the block is Blue/Gold/Green with a Red top coat, ?

regards mike

Although my research has proven to be accurate, the assumed "Shift" character has been a challenge, and not conclusive at this point. But the Day/Month/Year has proven correct results. (so far)

I have compared these casting Mark's with information I have collected on the cooper s bearing cap numbers.

In vast majority of cases they match .

There seems to be quite a variation in block cast dates to engine number / car build dates .

Some went from casting to finished car in less than a month , some took considerably longer.

Obviously if you have a 1963 car with a block cast in 1964 it's not the original but it seems some castings did linger about a factory for some time

251 ENG wrote: ↑Tue May 25, 2021 7:03 pm I have compared these casting Mark's with information I have collected on the cooper s bearing cap numbers.

In vast majority of cases they match .

There seems to be quite a variation in block cast dates to engine number / car build dates .

Some went from casting to finished car in less than a month , some took considerably longer.

Obviously if you have a 1963 car with a block cast in 1964 it's not the original but it seems some castings did linger about a factory for some time

Correct Simon
I have two blocks here, both are 6 weeks from the time of casting, to actual Car Build dates.

The block casting date for my MK2 ‘S’ was 30 April 69 and the build date was 6 June 69.

Took a look at a late AEG151 block. Similar but perhaps slightly different order: 15 J4 C.

15th Sept 1964 C shift?

HI 251 ENG
this block I have
D 21 J 6 with Mowog below it and it is a AEG312 under the oil gallery, also the engine size tag is missing

would this work out to be ;

Shift "D" 4th
Day 21
Month Sept
Year 1966

main cap No' 5315 with 1P stamped above it on all 3 caps, the No' 5315 is also stamped on the fuel pump casting and not near the water pump

regards mike

Just for interest & comparison of BMC blocks, the block dating method for the 1275 engines fitted to MG Midgets varies somewhat to Minis, the attached photo shows a casting number of 04K on the rear of a thick flange block fitted to my December 1967 built car which has the original engine number in place.

Good to see Simon has written this up in the July CooperWorld magazine, and extended it for the second decade [Mk3 S] numbering scheme also.

iain1967s wrote: ↑Mon May 17, 2021 1:13 pm Assuming "S DD M Y" format of the block date code:

S = Shift. A=first, B=second
DD = one or two digit day-in-month
M=Month letter, see note below
Y=Year digit

So far, we have found photos/details of AEG312 blocks with all letters A through M except B,E,I.

I suspect letter "I" is skipped, so the resulting table would be:

A Jan
B Feb
C Mar
D Apr
E May
F June
G July
H Aug
J Sept
K Oct
L Nov
M Dec

Props to Paul Harris [TECH396] for the groundwork he did identifying sequences on other marques.

iain1967s wrote: ↑Mon Jul 26, 2021 1:48 am Good to see Simon has written this up in the July CooperWorld magazine, and extended it for the second decade [Mk3 S] numbering scheme also.

iain1967s wrote: ↑Mon May 17, 2021 1:13 pm Assuming "S DD M Y" format of the block date code:

S = Shift. A=first, B=second
DD = one or two digit day-in-month
M=Month letter, see note below
Y=Year digit

So far, we have found photos/details of AEG312 blocks with all letters A through M except B,E,I.

I suspect letter "I" is skipped, so the resulting table would be:

A Jan
B Feb
C Mar
D Apr
E May
F June
G July
H Aug
J Sept
K Oct
L Nov
M Dec

Props to Paul Harris [TECH396] for the groundwork he did identifying sequences on other marques.

Indeed nice to see it in writing. My notes on the subject took up 10 pages lol I never felt the need for refinement, until now. Much nicer to see the refined version. Cheers for the honorable mention here Iain..
Paul

HI

picked up a 2nd block for the Terrapin that is a thick flange block as the original engine that was in the car,

it has a casting No' (screw head) A 21 D 1 with MOWOG under it, on the back, under the oil gallary;

A 1st shift
21 day
D month April
1 1971 ?? would this be correct, as it has open tappet chest's/covers

also there are 2 casting No's near the oil pump oil gallary feed AEG312 at the top, then a diamond with a M in it, below is AEG 634

regards mike

21 day
D month April
1 1971 ?? would this be correct, as it has open tappet chest's/covers
also there are 2 casting No's near the oil pump oil gallary feed AEG312 at the top, then a diamond with a M in it, below is AEG 634

regards mike
[/quote]

Yes Correct. It's the last of the S blocks

HI Paul

do you know when the thick flange block's came into production, as I am trying to date the original engine I had in the Terrapin (no close up photos of the block) all I know is that is came out of a rally car in the Oxfordshire aria (I think, will have to ask some Questions)

regards mike

Terrapin-52 wrote: ↑Wed Sep 01, 2021 8:45 am HI Paul

do you know when the thick flange block's came into production, as I am trying to date the original engine I had in the Terrapin (no close up photos of the block) all I know is that is came out of a rally car in the Oxfordshire aria (I think, will have to ask some Questions)

regards mike

Mike
Based on the information available here, it was somewhere around April/May 69 .I recall another Member shows it to be around engine # 536***, there's more details on the subject (on this thread) if you scroll to the beginning.

Reviving a thread from last year, I was inspecting a late Mk2 Cooper S / Australian Clubman GT block that I am getting ready to build up. It has the casting code "M 12 E 0" on the rear of the block.

I don't know what the Shift code "M" could mean, but I guess from the rest of the code that the production date would have been 12 May 1970?

The block is a late thick flange S block with the extra vertical rib near the dipstick hole. Engine number is long gone (ex race motor).

I have a 634 block with the same 'M' coded prefix...