Well I think all new-style (1974 and newer) A12s have two bosses, but usually only one of them is drilled for a drain plug.

* New A12 has offset middle core plug (same as original A12), but with two drain plug bosses. Usually only one is drilled & tapped for a plug.

* A14 has centered middle core plug and single drain plug boss

Here is an M22(?) block A12 engine. Notice it has the new-style motor mounts (it is a mid-dizzy engine).



If this block is fitted to a Datsun 1200, the motor mounts need to be modified or a short/tall crossmember fitted.

Quote:

Haven't come across that before. Even the last 1994 A12 used 35mm welch plugs.

that block looks the exact same with the back welch plugs and bolts
and the dizzy is mid mounted id say with a electronic dizzy aswell
the last owner didnt know much and he bought it like this

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  m2 block.jpg (151.14 KB)

and this is the engine bay

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  1200 engine.jpg (116.54 KB)

and no picture of the crank i actually just put the sump back on im affraid

All newer A12s have a lightened (scalloped) crank, starting with cranks made October 1979, as in B310 Sunny, N10 Pulsar, 1200 ute, and C120 Vanette.

'M2' blocks reportedly are factory replacement blocks and if so, they would have the newest components. The new A12 crank is even sold by Nissan USA (part number 12200-H8560).

Replacement A12 crank



Original A12 crank

RE: Welch plugs

Per all the Nissan parts catalog the welch plugs haven't changed size. I looked in these catalogs: B10, B110, B210, B310 USA, B310 Japan 1982, E10 1974, N10 1982, C120, C22, B120 1994.

That being said, I found some welch plug sets for "120Y" and "140Y" that
show different size plugs.










See Welch Plug section "Sets"

sweet as
thanks mate