well my home is very good and datsun friendly.

This is the guts of it guys, we're trying to make 70's technology heads flow like it's a modern 16 valve.
while the kind of flow figures you see from a stock SR head are just accepted these days, that'd be a damn fine A series head.
this work is expensive!!!!
Everyone thinks they can pick up a die grinder and make it work 'as good as my mates friends brothers racer' (and hey, i've been there), but the truth is that good A series heads are rare, the thinwall ports leak like buggery, the combustion chamber wont deal with crap modern pump gas, the rocker gear is fragile with the heavy springs and hi lift cams and the heads fall off the big valves when you rev them...This can all be fixed, but you could buy an entire CA + computer + box for the price of a good A head.

Yeh I guess I could let a couple go to a good home...

stirlingmac sinse you have so many just lying aroound doing nothing, you could spare one or two then? couldnt you?

Yep I am serious...read again what I wrote..on an otherwise stock engine a GX head makes no difference. As for them being rare they aren't here in NZ .There must be at least 6 on the floor in my workshop. The larger ports don't work well with a standard style carb and manifold, but are tranformed with a decent manifold and sidedraughts, they are a big hole for a stock carb to fill. Dual valve springs in a street engine don't do a lot, they were homologated for racing at high revs 7500+. The chamber shape is excellent on a GX but High compression with the crappy fuels we are forced to use is quickly becoming a thing of the past. The GX is a bloody good production head but on it's own it won't turn your car into a rocket ship.......

Oh, the GX head is useful alright ... it's 1 pt higher in compression, which for some is worth it right there. And it already has the big ports. As stirlingmac points out if you have a freer-flowing carb and exhaust system the head will make a difference over the stock A12 head. The manifold mounting is slightly different but that can be modified as well.

But on the other hand it doesn't necessarily cost a lot to port an A14 head ... $100 worth of Dremel rotary tool and you can port it yourself. You have to ask yourself, do I like to do my own work and learn (possibly by mistake), or do I need a competitive engine with the porting done by an expert? If the latter, you may want to pay the experienced porting expert for guaranteed results. Wagon_boy said the GX head worked well for him but had "plenty of head work" done to it ... so he wasn't commenting on a stock GX head.

My point about the GX head is that if 1) you already have an oval port A14, and 2) you want to run regular fuel (not pay the 15% extra for premium), the GX head may not be what you want.

Tech Section article
Datsun A12GX Engine.

the GX is the factory A series perfromance head right??

which 1200s were they in, the GX engineS?

im starting to get this theory that people that cant find/dont want to pay for a GX head get a complex about it

then deny at all cost any benefits it provides

lets face it, every performance build up on every car ive ever seen takes a standard head like our non GX version then does all these mods to it which just happen to be the same ones the GX head has

thats no coincedence

only reason they arnt on other blocks is not cause they aint worked but because its cheaper to make ####ty heads

wasnt it you stirlingmac in the other thread that said the GX only had a mild cam????????

yeah i think your right, increasing the size and ability to flow is not very beneficial, neither is increased combustion and ability to rev harder has no benefits what so ever

gees man are you serious?

Another thing which people fail to understand that the addition of a GX head to an other wise stock engine gives you no more horsepower. The GX is the base for around which you build a more powerful engine. As is always the case it the combination of, cam, ignition, CR, and fuel that creates the power. Different combos for different requirements. The twin Hitachi SUs were there to allow the use of twin choke carbs in various racing classes. The exhaust manifold on the GX allowed for a freer flowing system. The ignition had a unique advance curve. And so on and so on.