Hi can anyone tell me if the a12 head is a straight bolt on fitment to an a15 block ..
I know its not as good as the oval port but have bike carbs on the 1200 engine & janspeed exhaust , so just as a try out why i get new headers/ inlet constructed
i want to really run the engine.
thanks in advance

yes i cant see why not ,ive got a h89 on my a12 ,so it shoul work both ways ,and the gaskets are the same

as long as the head is a late model a12 head ,not off an early a12 with the dizzy up the front of the block

yes you can but why would you...you would need and a12 carby as the manifold for the a14 and a15 carby is different

Sounds like you have everything separated so why not drill, tap and install the relevant new manifold bolt pattern on the oval port head (if it needs it) or just bolt the round port manifold to the oval port head if it shares that bolt pattern already.

Don't think you need an A12 carb at all. Bike carbs would be much better.

Can you upload a picture of the Janspeed extractors, is there much of that stuff around (or do they still make gear for the A-series?).

http://s810.photobucket.com/albums/zz22/paul3366/?action=view¤t=2011226.jpg
this is how the engine is in 1200 R1 bike carbs and janspeed .
I now have a A15 engine obviously the oval ports are different so why i was waiting for new inlet manifold i was going to use the A12 head bike carbs and janspeed manifold with a 244 kent cam upgrade 3k-8k range so should liven up slightly

Sorry you misunderstood me.

What I am saying is use you oval port head with the round port manifold and R1 carbs.

Oval port head has bigger valves and a better combustion chamber so it would probably bring better performance even though there is a misalignment with the ports.

oh and janspeed are not making manifolds anymore, i was in the right place right time for a change
[IMG]http://i810.photobucket.com/albums/zz22/paul3366/DATSUN%20B110/IMAG0518.jpg[/IMG]
Its hard to find parts in the uk and i want to stay true to the nissan ..

clyons 8 I did understand you. the present manifold doesnt have enough metal mounting plate to cover the inlet holes in the head so bit of a dead end

Quote:Correction

You CAN use the early [front distributor] head on the later cylinder block as the oil feed to the rockers is pumped directly up the correct head bolt hole in the cylinder head.

You can NOT use the later head on the early block because the early block feeds the rocker oil to a small vertical drilling at the side of the cylinder head gasket face. The cylinder head needs a corresponding drilling that feeds the oil across to the same cylinder head bolt hole as the later engines.

Since the newer heads do not have the drillings necessary to pick up the early engines oil feed, the rockers will not get any oil at all with predictable results.

I have looked at both heads a12 & a15,in both the oil feed comes up the central rocker-post via a head bolt.
Im going to crank the engine over (without plugs) to check oil is being fed to rocker assembly , this hopefully will be ok then its