A guide so far not the best written so excuse me Im more and more short for time lately but will try my best with permission from the AB series owner:
This is for the Datsun community as always and for my enthusiasm/hobby so no
profit or gains are made as we are all enthusiasts tinkering away for fun.
I see the more peeps find the A series still a force to be reckoned with the better meaning more will be saved from scrap and stay on the road, track and sheds as they are fitted on all datsuns, austin sprites, mg midgets, Morris minors, Austin of all kinds, Speedway or circle track and many other cars I have not listed but exist eg. suzuki sierras, boats all over asia & more.

So here goes Datto folks......
drill and tap block to fill pushrod holes
drill and tap for screws to go on the oblong shaped oil drains
fill oblong with metal filler
block oil feed to head from block (another method is available)
run oil feed from side boss covered by brass seal or from the
rear by drill and tap then feed to head.

Bore to 77mm for HD daihatsu pistons or
Bore to 78mm for stock Mazda b6 pistons
19mm pin on A15 can be used
17.45 pins on A12 need bushing pistons

New method for using side water inlet for electric or
mechanical pump (a few options avail for Mech)
New method is ridiculously easy and trouble free
Keep block in camshaft for oil pump and fuel pump
if running carburettors, dizzie or modded sump
can be used to drain oil from the head

Head mods require some drill and tapping of oil drain
holes no big deal and easy redrilling and tapping to
suit brass fittings like on CA18de/t extra oil draining
Oil drain can also be made from head into the dizzie
cavity area using a simple plate with tubes or if running
efi you can also use the fuel pump cavity instead or
as well its your choice but Im using sump drilled and
tapped for brass fitting so requires no welding.

Run cam extra Mazda b6 camshaft pulley on original
A series block camshaft, the cam is sealed by a custom
cover that bolts on to the custom front plate, there is
also a crank snout cover for the front crankshaft seal.
The front plate seals up the sump as well with a semi
circular piece of alloy welded onto the front plate &
two taps on the sides to allow original sump fitment
and sealing. There are no leaks whatsoever and a very
clever way to avoid any sort of welding or heat being
applied to the original sump.

Headgasket is custom, some of the water galleries need
a little tweaking with a die grinder but otherwise its
a very just fit on the block and head in terms of all
holes been very compatible. Dowels can be matched to
suit the B6 head for alignment very easy again.

Cam belt no. already sorted and easy to get anywhere.

Some pics will follow and a better detailed guide
for those interested in doing such a conversion
with is possible to those with a little tinkering
ability nothing major, but essentially the front cover
and the headgasket are the main pieces of this build
sorted out while then the rest falls into place.

The rewards of this conversion are endless and the
camshaft cover choices are so many not yet counted
for but Mazda has 3 for the B6, one like shown in the
original conversion, 1 or 2 rounded types as on Mx5
of different s1 and s2, Ford Laser has 2 depending
on model s1/s2, Kia has several alloy and plastic
rocker covers Ive yet to count but so far 3 I could
see where distinctly different from model, years etc.

Then there is the choice of the 8v sohc and 16v sohc
which is what is been converted atm for another build.

Ignition is via megajolt jnr crank ignition to run carbs
or many sorts, eg. weber manifolds are available or use
bike carbs using pipes welded to original flange.

Mazda ecu can be used for crankfire ignition also but
to run ignition alone has been done on the miata USA
forums with no info at hand yet.

Otherwise Mazda efi can be used or aftermarket ecu
depending on the needs of the owner.

edit: here are some primary water & oil mods
for my AB16 and AB11 (a15 78mm & A10 76mm)
Although not necessary as the front cover
seals this area well and only needs the hole
made to pass through the block wall from the
side entry point to access but.... Im fussy.
A10 illustrated below for reference.

Attach file:

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  twin cam A series water mods.jpg (161.25 KB)


  datzda oil mods.jpg (183.55 KB)