i am building up a A14 with A15 crank & pistons, A12gx head with stock A15 valves, ported and shaved, very mild cam. i wanna use the stock GX exhaust manifold but have a good exhaust.

my question is how do u guys tune your motors using the datsun su's? ive heard of re drilling the carbys to fit proper su needles but is this the right thing to do? are there any other options? i really really really wanna use the stock su's as im buiding up a
datsun 1000 GX-delux ute, if u understand all that

I have never had a problem tuning the GX setup,
what exactly is the problem with your stock Hitachi needles, that makes you want to redrill the carbys?
Are they bent?

Sidedraught....do you really own a Datsun Fairlady like the one in your avatar?

Yes Mildman that car in my avatar is parked here next to the KB10 and the 120Y.

Nice indeed. My girlfriend is slowly getting the Datto bug - and is thinking about getting herself one of those old school fairladys. A very cool car in my opinion!

isn't that where needle profiling comes in?

I think you can shape the needle to fine tune, but i don't own one of those things.

i would also like to know a little info on these carbys...
but will get a professional to do the fine tuning on my car...
im a little unsure about the tune of the gx carbs im using, as they have been rebuilt and unused since..
i they are setup rich for the engine run in. but will need a good tuning aterwards

are their any to notch tuners that can tune this setup on the gold coast/ brisbane??

pm me if u know of anyone

With a mild A15 we have found that

Pommy SU Needles defined as GX profile where the ones to use

Very odd that they where called GX but coincidence only these are close perhaps a bit rich on cruising