I just stripped an 1100S (aka Morris/Austin 1300) motor, the crank is stamped 12G1288, (small journal non-crossdrilled) but under that number I can see other forging numbers too. I reckon they maybe only had 1 forging and ground various cranks from this and then stamped them.
Who knows... it's been 40 years.

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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.

Managed to get five minutes in tha garage..

the crank is cross drilled two holes each side with one blocked on a right angled

no markings such as en40b any where on crank..

Kiwiinwgtn

kiwiinwgtn,
What you have appears to be an OZ MK2 S crank. I'm not sure but I think this was also used in the UK MK3 S since all S engines and gearboxes were supplied from the UK.
When the OZ MK2 S was released one of the criticisms was that it didn't have the EN40B crank. It had the thick flange block and the 4 synchro box but no nitrided EN40B crank.
These were made from 12G1505A forgings, ie 1275 big journal crank forgings and ground to suit the S block main bearing widths, which are narrower than non S 1275 blocks, and the small journal big ends. The cranks were tuftrided, not nitrided because they are EN16 material which is not suitable for the nitriding process. EN40B is a steel suitable for nitriding.
Alternatively check the main bearing thrust washers and if they are 0.030" O/S?? then someone has reground a big journal crank to small journal size to fit the S. You need O/S thrusts to compensate for the wider main bearing width in non S 1275 blocks. If you bust an S crank this is probably the cheapest way to get a new crank.
In another BMC puzzle I think they used the same part no as the EN40B cranks, AEG 480/479. The 1 digit difference occurs in other areas of the BMC numbering system. Another example is the C-AEG 648 cam which appears as 648 or 649 depending on the publication or parts list.
The cross drilling was introduced at approx engine No9FSaY 42xxx. It only applies to the bigend journals and as the DOC says it was done to reduce oil starvation of the main bearings at high revs. Should be 2 holes at 90degrees to each other and the oilway drilling to the main journal should be plugged.
No idea what the GE622 number means.

Hope this helps
RonR

hey guys i'm a bit confussed when it comes to all these numbers for cranks. But im about to build a pretty strong 1275 which will be getting suprcharged what type of crank should i be looking for i know the EN40B seems to be the way to go but they are hard to find and dam expensive so what else is there.

cheers dan

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Cheers Dan

FIRST COMES THE MONEY, THEN COMES THE POWER, THEN COMES THE WOMEN.!!

thanks Miniron

Your detialing regarding mark two OZ S crank certianlly helps,

so it is most likley a en16 OZ mark 2 crank cross drilled in a mark one thin flange S block,

This supports my thoughts that the engine is an OZ s as the gear box is a close ratio four syncro with hardie spicerer out puts

I also thought they never crossed drilled the En16 cranks

Thanks

B

I have 2 EN16 small journal 1275 cranks here, one is crossdrilled, the other not. Both are tuftrided, the webs are impossible to file. Hard as...
These are both out of Oz Morris 1100S blocks- the early thin flange one had the crossdrilled crank, the thick flange block had the plain one.
I'm pretty sure the Mk2 S version of these cranks were all crossdrilled.

Badass, either of these EN16 tufftrided type cranks would do you, but personally I'd select a crossdrilled one if you are going to give it a big rev.
re the big journal cranks, these (EN16) were all left soft by the factory, out here anyway. But rumour has it some Metro Turbos in UK got a tufftrided one.

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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.

thanks doc

what engine number did the 1100s have.

did they have close ratio gear boxes

The Morris `1100S' (1275 donk, same as your Austin 1300 really) had a 12Y/Ta/H or 12YD/Ta/H prefix.
No, they were similar gear ratios to Mini Deluxe etc, not Cooper S ratios. 3 synchro too.

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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.

hey drmini thanks for your reply how hard is it to find a EN16 crank and how much would i expect to pay.

cheers dan

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Cheers Dan

FIRST COMES THE MONEY, THEN COMES THE POWER, THEN COMES THE WOMEN.!!

Good cranks are getting rarer, for EN16 ones (either small journal or large) I would expect to pay from $250 up for one that's not more than -.020" journal sizes and needing a regrind.
A full standard regrind costs around $150, if you want a big journal crank stroked as well, add another $100.

EN40B nitrided Cooper S cranks are worth more, probably $400 up- because everybody seems to want one- but really these are getting brittle now. They are 40+ years old. Many engine builders won't put them in race motors any more. They prefer a tufftrided EN16 one, or a nice shiny new EN40B ($2,200 up, you can spend $4K on a race crank).
Old EN40B S cranks are great for a street motor though.

Put an ad in the wanted forum, you might get lucky. Or ask around Mini parts shops.

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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.

cheers mate

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Cheers Dan

FIRST COMES THE MONEY, THEN COMES THE POWER, THEN COMES THE WOMEN.!!

hey beranrd check to mkae sure that its not a GT cranks form this side that has had some work done on it as they samped into the crank 12G1505 numbers but when they balance them they tended to grind half the numbers off.
was tuftrided instead of nitrided so came out in a grey colour.

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www.minicranks.com add me to your watch list and come back again soon, under construction.

cheers, it is cross drilled, looks like the engine is an oz S mk1 engine from all the other bits surounding it. with a mk2 oz crank which is standard journal size..

Cheers

B