I went rummaging through a small pile of Datsun cranks today as I figured it was time to move my A13 project ahead & since the entire engine has to be built entirely from parts, starting with the block, it was time to get a crank.

I laid out about 5 or 6 of the 1200/ A12 cranks on the floor, & since the 1200, A12, A12A & short stroke A13 all share the same 70mm stroke, then any crank from one of these will fit any other block from the group.
In Australia, pretty much any 70mm stroke crank that you find will be a 1200/A12 one.

Each one was tagged & surprise surprise, there's an A13 one. Better yet, it's the original one from my block.

When I compared it to all the other 1200/A12 cranks it became obvious that it is different. It's dimentionally interchangeable, but is based on a different forging.

This one has 'scoops' in the web in line with the main bearing journals & this would have the effect of reducing the weight of the crank.
The other cranks on the floor in front of me were all marked as A12 & all were machined straight in this area.

There are two versions of the A14 crank also & the more common one is the lighter one & it too has the 'scoops' in the forging.

I now assume that this design was a production revision after a certain date but would have coincided roughly with the B310 models as these are the cars that got the A14 in Australia & this version of the A13 in Asian markets.
The A12 & A12A were also used in B310 models at this time in various markets & both had the 70mm stroke so I wonder if they used the same crank.

I will try to get a comparison shot of the earlier A12 crank soon.
The grotty journals are just that, grotty with heavy oil & a lot of dust & dirt.

Should I knife edge it?

if your budget allows. Thats one of the "fancy mods" i'd love to do, but due to budget constraints it aint gonna happen.

Quote:

I think you know the answer to this. By what you tell us this engine is going to have all the good bits and be one efficient 1000 pushing machine.
Cant skimp on it now

This one looks similar:



A12 crankshaft from Yahoo Auctions


Were there any cast A-series crankshafts?

more linkys
right here

You have already thrown heaps of dosh at this motor for what is aparrently going to be a mild motor. Why not knife edge it and nitride it also for good measure. Not because it needs it but because you can. Then you can post up your Cash to Kilowatt chart and we can all hang it on you!!

Knife edge it. Do it! Do it! Do it! Do it! Do it! Do it! Do it! Do it! Do it!

Quote:From the posts I think that my first guess was probably right.
There was a running change in the 70mm stroke cranks after a certain date & all of the A12, A12A & A13's used the same crankshaft since, with the exception of the bore size, they are all essentially the same short block. [Heads may differ]

I wonder if anyone in Australia has a post 1980 A12 engine in pieces & can confirm that their crank is the same.
I'd make a small wager that it is.

I do not believe that any A series engine came with a cast steel crank. All the ones I have seen have been forgings.
Should we expect anything less of the worlds best small pushrod Four???