LTR,
I think you might like to do a little more in-depth research into the AY Crossflow engines before you get too deep into this project and make a fundamental error which will be costly to correct.

Here are some scans from an article that OLD TIMER Magazine ran back in February 2005. They show the very engine that I photographed in Japan, and they give a little bit of historical background on the story:




Notice ( if you look carefully ) the second set of spark plugs located underneath the area where the exhaust valve rocker shaft would be.

End-on view:




Oil pan on this particular engine is wet sump version.

And a picture of the heavily domed special race piston for the AY Crossflow:




( Above three images courtesy OLD TIMER Magazine ).

The magazine article reported that the FIRST version of the AY Crossflow was a 'Single Ignition' version, and this was soon modified to the SECOND 'Double Ignition' version - which was more efficient. As the FIA homologation papers show the FIRST version, it is possible that the JAF homologation papers ( covering domestic racing in Japan ) may also cover the SECOND version, or it was being used prior to proper homologation and the then-current homologation was going to be retrospectively updated ( which is not an unprecedented situation ).

I would have thought that the correct ( hemi ) pistons would be a REQUIREMENT for this layout, rather than an option. Anyone planning to use modified versions of pistons originally designed for the Counterflow A-series heads would be well advised to think again.........

The OLD TIMER article gave some period data sourced from Nissan's Omori race team ( which prepped the cars concerned ) that might be a fair guide as to what to expect. They said that the non-Crossflow A12 with twin 40PHH Mikuni-Solex carbs gave 100ps at 8000rpm.
The non-Crossflow race A12 with Lucas sliding throttle injection gave 150ps at 8500 rpm.
The AY Crossflow with Double Ignition and injection gave 160ps at 8800rpm.

Alan T.

Quote:

I'm afraid parts like these don't normally change hands on the open market, and you would need to be introduced to a seller via a mutual friend. You would also need rather a lot of cash in your hand at the right time.

Engines like these really ought to be reunited with 'historic' cars ( or at least good replicas of them ) and you will find that there is rather a lot of sentimental value attached to them too. People who own stuff like this tend to want them to go to the 'right' home - if you see what I mean.

Quote:

Yes, it does.

The car is is part of Nissan's collection, housed at Zama and used for demonstrations / displays regularly. It still runs well and normally takes part in the NISMO Festival events.

LTR,
An acquaintance of mine has a complete 'AY' engine sitting on a trolley in his garage:







Note the 8 spark plug wires, and the angled distributor drive take-off. This engine consists of a lot more than just a cylinder head casting.......

If you need to conform to FIA homologation specs for your car then you will need to follow the homologated specs for the distributor drive too - which will be tricky to engineer if you do not have enough data / samples to reverse-engineer from.

You might even find that it is more cost-effective to buy a complete head kit / engine from Japan rather than making your own. Such things are available if you know the right people to approach and you have deep enough pockets.

And at least you would then have the real thing too, wouldn't you? You could consider it as an investment.

Good luck,
Alan T.