Iam wondering which head is better?
One head I have has very high (oval) intake ports, and larger than normal water ports just below them. It has however, smaller valves than an A14/15 head and no part numbers
under the rocker cover. Would it be worth putting the bigger valves into this head?
What is it off? What compression did they run? would Ibe better off getting work done on an A14/15 head which already his bigger valves? Does anyone know if the high
port head has any better flow caracteristics?

So if you have a few clues about Aseries heads please contribute your two cents worth.

many thanks

Bart

I'd probably stick with an A14/A15 head then carry out the head work necessary to suit the engine you are building.

Its better to stick with what you know and you will know what has been done.

Hi Bart, it sounds like it might be the A12GX head. Have you seen our tech section article A-type Cylinder Heads?

If you want to pay for high-octane fuel, then the high-compression heads are best.

Aside from having higher comp, does anyone know if the higher ports give better flow? Also what manifolds ( inlet) are available for these.

Bart

higher ports don't affect compression ...

I would go go for the A12GX head and fit bigger valves in it..... It

The best head is the oval port A14 head with the larger 360 degree "open" combustion chamber. It is arguably better because it has the same large size valve and port sizes as the standard A15 head plus the larger combustion chamber enables you to use forged flat top or domed pistons if you really want to go hard core. Otherwise the best value for money is the standard A15 head (not the swirl pot version, which i'm yet to see).
You can easily shave 80 - 100 thou or more off these with no worries on standard pistons to up compressions.

Hope this helps.

Ive gone back and reread the tech section and some old posts, if the compression ratio is 10:1 on an A12GX any one keen to guess what sort of commpression the gx head would make on an A14 OR A15? Has anyone tried this? Do you think it would be too high
for pump gas, or would it make her a race fuel only job? If someone can help me with this one ,it will save me from having to
measure the chamber volume myself( atleast for the time being any way).

yeah i have a A12gx head on a14 block, bored out to 1434cc comp of 9.91:1 well pretty much 10:1

runs good on premium havent dared put REG in, wouldnt do that to my DATSUN , but would run on the REG fuel just less go go go

generally anywhere up to 12:1 comp can still be run on premium pump gas