Hey guys recently bought my first datsun a 1200 sedan
it has a a12 engine but it's not the original one and it was m2 in thr block and extra welsh plug trying to find the size for it and whats the difference apart from a lightened crank
Did a little sesearch but thought id ask
thanks

Newer A12 used an M block. There is no difference between it and a 120Y block, except for the water inlet tube and block breather tube.

im trying to figure out how to post a photo from my phone to show you even has a nother bolt in the block next to the other one

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Yes, I see what you mean. Here is an original H10 (Datsun 1200) block to compare. I see what look like two drain plugs in your photo, but only one in the H10 block.

What is the casting number on your block?

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Says the model is a12 but has a big m2 embroidered into thr block on the same side as the welch plugs
and its alot smaller then the normal 35 mm messaures to about 25mm

I'm not too sure about the validity of the M2 block containing a lighter, scalloped crank, I have come across many with just the normal crank.

Would you happen to have a picture of the A12 M2 crankshaft in your engine?

Regarding the 'extra' on the M2 It looks like another threaded port into the side of the block.

There were also older M08 blocks for A12 engine, but they did not have two plug bosses, at least not the ones I've seen. They are identical to Datsun 1200 block as far as I can tell except for the bolt on parts like oil pan, water input tube, etc.

1971 M08 block

It isn't an additional port for a cold preheat plug? Used in cold climates to de-ice the block coolant?