Hi all

I am interested in getting another GX head but know this is going to be a challenge to get as they are very scarse to find.
What head can I use to modify to get the same results as a 1200 GX head?
I know the 1200GX head has oval ports and double valve springs for higher revs.
I want to build much later a 1200 race spec engine but do not want to use my GX head as this engine I want to keep standard.
I want to use another head for example A15 and modify it to get the same comp ratio and double valve springs effect.

Can anyone give me some ideas?
Thanks

Any of the Datsun Competition/Nismo heads -- they also have the high-compression chambers and oval-shaped ports. These were available for A12, and A14/A15.

I hear what you are saying.
But I want to use a head that if it gets damaged or something it is cheap to get replaced.

Also those heads are expensive.
It is cheaper for me to just get for example a A15 head and modify it to the same specs as a racing head.
Is this possible?
For example A15 head.
Skim to get 10:1 comp
And do something to fit doublevalve springs.

Yeah, do that. But look for a head with the small chambers to start with.
You can fit double springs to any a series head, but it pays to mesure the installed heights of the valves, and shim them up acordingly.

How much must I skim to get 10:1 comp on a A15 head.
Or will the cylinder head place be able to calculate this for me and do it.
Must I get a round port A15 head and let it be ported and gasflowed.
I guess it must be round port because it has more "meat" to grind away when porting.

Did anybody have success in putting a A15 head onto a A12 block?

get an oval-port head to start with, one without the restriction in the port. Most round-port cannot be ported to oval (but some can, there was a thread recently here in the main forum).

Some oval port A14/A15 are high compression already, so no need to mill the head surface to get 10:1 on an A12.

The main difference on the head (A12 to newer) aside from valve size, is the hole between #2 and #3 cylinder pushrod passages.

Its always better to weld up chambers and decrease chamber capacity than to skim the head.

The answer useful to you may depend on what models/engines were sold in your country.

I know that here in the U.S., you want the B210 (120Y) GX head. It has the correct flow design and some even have the larger, oval ports!

The A15 heads are bad news (at least the U.S. versions) due to the "toilet bowl" flow design. And the cams on these motors are also junk.

We have one of those places here that sell japenese second hand imported engines.
In the bunch there is A15 engines.
This is what I was told when I phoned a while back.
The guy there could however not tell me if the heads are round or oval and said I must rather come and take a look myself.
I do not know what the engines came out of and I think he will also not be able to tell me.
Is there anyone that can maybe tell me a number like the GX head has that I can look for on the A15 head to know if it is the correct oval port head and maybe with 10:1 comp?
The head without restrictions?
Thanks

Did you see our updated tech section article A-type Cylinder Heads?