""The real big-block version of the A12 is the one-year-only 1974 A13 engine: A12 pistons but with a longer stroke. Put into a larger engine block so the rod/stroke ratio is favorable""

If its stamped A13 its an A13 not the real big-block A12, A12 is A12 no fooling anyone there either.

Taller block A13 is a new gen caste block as found on A14 and A15

A13 tall block is probably has the thickest casting and prob the heaviest
of all the tall blocks and suitable for turbo.

I wonder if early A12 is heavier cast than later A12

better photo

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A12A is stamped

It came in
* every B310 USA (1979-1982)
* every B310 JDM sedan & coupe (wagons had the A12)

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A12A is stamped 'A12A' so no fooling anyone

There are two A13, the tall-block A13 and the regular block A13 (basically an overbored A12)

A13 stamped still A13 though for if you bore it to 75mm you get pseudo A14
It has an A14 crank stroke and taller block than A12 or is it same height as A12?

Yes, I replied to Flat Top Pistons for A12A the K15 stroke is listed there

The real big-block version of the A12 is the one-year-only 1974 A13 engine: A12 pistons but with a longer stroke. Put into a larger engine block so the rod/stroke ratio is favorable

A12A sounds like the big block version of the A12!

DD did you find what bore and stroke the K15 engine has?
its the only one missing in the chart
https://jp.made-in-china.com/co_union- ... n-Kit-K15-_heignriyy.html

A12A was used in B310 in JDM and USA -- all JDM sedan & coupe advertised as "A12" actually had the A12A. It is 1237cc with a bigger bore, compare to A12 at 1171cc with smaller bore

where does the A12A fit in DD if Murica got mainly the old A12?

TexasMidget asked:
Quote:There are quite a few changes, none related to performance or durability. The same strong crank, overly strong rods and robust cylinders are used

The changes are mostly related to getting more room for engine accessories, namely better AC compressor placement and smog pump

* Distributor moved from front of block to middle, allowing to move alternator to right side

* Engine mount brackets moved back to make more about 1" room (and so fuwl pump moved forward, which in turn bumped to dipstick to a new location)

* Due to dipstick location change, slight change to oil pan. New A12 and old A12 use nearly the same pan but with room for the (moved) oil dipstick. The new A12 oil pan is same as A12A/A14 pan, which is commonly found in Americas, so no worries find a replacement oil pan

* New crank uses all-metric bolts. This is a standards change, not a performance factor

* No limitations with cylinder heads, any of which can be used with old engine or redesigned engine

* Advantage of old A12 for Americans is that it was the only A12 sold in USA/Canada, so is more readily available. Advantage of new A12 is more room for engine accessories like AC (old A12 used complicated bracket to do this) and turbo fitting

For more details see our tech article A Engine Redesign

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