Hi all you Mk 1 S owners,
I've noticed that the engine block stampings on our cars have a mixture of either the upper case "A", or the lower case "a' included in the 6mm stamped 9F/Sa(A)/Y ****. These blocks were restamped by BMC after the riveted tag with the original engine number was removed to satisfy the Aussie Authorities, (the tags all had the lower case "a").
I have two engine blocks only 5 numbers apart & they are both most definitely stamped with the same set of 6mm punches & include the "A", but I note that on two 1965 cars I know of, the blocks are stamped with the lower case "a".
Checking around here with my Mini colleagues it would appear that the later cars were factory stamped with the upper case "A", so could any one solve this riddle? - I'd be happy to collate a list of cars by build date & whether they have "a" or "A" so please check you block stampings & let us know?.
If you are unsure of the build date, maybe the car number?
BTW, The two blocks I have haven't been re decked!
Thanks for humouring this Mini tragic with OCD....

My Mk1 S was a 1968, it was 9F/SA/Y prefix. Upper case...

[edits] I have another ausmini member's Mk1 motor here at the moment, it is also 9F/SA/Y prefix and the stamping looks original, it has been decked a little.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

ooops have corrected that

My 'S' is a late 1967 and has the large 'A' on the block and small 'a' on the ID plate

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1965 Morris 850
1966 Morris Mini Minor
1967 Morris Cooper 'S'
1977 Leyland LS

I have an early 69 Mk1 with Large "A" on the engine block and small "a" on the ID Plate.
My engine is 60thou over so I think you would get a more accurate database using STD engines as a reference.
I would expect that my engine has been decked at some point in its life.

The ID plate stamps are interesting. It seems that they didn't buy a small "a" till they were in the 4000s on the Cooper. I would guess 64.
All the Cooper S ID plates I have seen have a small "a" and that goes for the Deluxe, Morris 1100, Austin Freeway, Wolseley 24/80 etc. as well.

The factory did use a small "a" on engine blocks. The Morris 1100 blocks have a small "a" and I would assume the Deluxe got it as well.

My Cooper S has a big "A", I don't think it has been restamped. If they were going to stamp it they would have done a better job.

So far, so good!

To my eye it appears that the locally assembled motors had the numbers stamped with a tool that held all the digits and the imported motors were stamped one digit at a time.

So which ones are Fakes?

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DID I MENTION THAT I AM THE BEST SUPPLIER FOR MINI ELECTRICAL PARTS AND REPAIRS?
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What is the reason/meaning behind the use of the lower case a?

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

Mine is also upper case on the block and lower case on the ID plate. 68 Cooper S. I don't believe it has been re stamped.

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

At a guess, so it didn't get confused with the other 'A's that were in regular use in the codes.

A = Automatic
a = Remote control centre change gearshift (always preceded by an S or a T)
S = close ratio
T = standard ratio
U = Centre change

Are they in a perfect straight line or do the vary a little?

Thanks for the explanation, and no mine are not straight they vary slightly.

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

Hi

in my collection.. no idea of build date, however numbers for your reference

This block looks to be about october 1965, so that would back up the theory that only the early (1965) cars were stamped with the lower case "a"..
Thanks for the info!