i would like to know how far i can go with gx head at w/shop eng - it is 74mm and they reckon std it is approx 77mm. will thicker gasket help and what is risky what are required changes

74mm is fine. You don't want to skim it any more. Why would you use a thicker gasket? Don't you want the extra compression ratio?

GX heads came stock with an extra-thin metal headgasket. If using the flat-top pistons it was 10:1 compression.

hi thanks for the info but the problem is it's 74mm still needs a skim that is why i am asking so what do you think-go and use gasket or leave

a good motor shop should be able to shave as little as 2.5 thousandth of an inch from your head. AFAIK, too high a CR, or piston to valve clearance becomes an issue before the head being too thin is a problem.
You can get off the shelf "head saver shims" to compensate for when the ehad as been skimmed too much. AA gaskets (In Aussie) can supply them. aj130s08 = 0.8mm thick and aj130s15 = 1.5mm thick.
get it skimmed, and them measure your combustion chamber volume, and calculate your compression ratio. As long as you can get decent fuel, (98 octane) 10:1 should be okay for the street, depending on your tune.

hi thanx for the info.the head is one i got and it is what i wanted a gx head. this head is scarce here in the rsa [cape town].just one prob i hate working on the edge.thanx anyway i will have to think it over.i have a14 that i am doing and i wanted gx head with bigger ports and bigger valves,flow,light flywheel etc etc

You might also double-check the need for skim. Most commercial places *always* recommend head-milling, even if it is not necessary. Nissan spec is up to 0.004 inch warp allowed. Few heads are warped this much.

Not a problem. Get it skimmed only enough and get a thicker than standard Payen head gasket that will bring it back to stock. My one mechanic friend here in Bloem said he did it a number of times with BMW's that had heads skimmed to the max. Upon request to Payen they make a custom thickness head gasket for him. He said he had one made 3mm thicker than standard and the car is still running fine without blowing head gasket or anything.
I think 77mm is the stock thickness as I have a spare GX head sitting at 76.9mm.

Gxman hold onto that head, they are very scarce here in our beloved country.

If you are in cpt you can make your a14 head into a gx head you only need the gx valve springs. A14 valves are bigger than gx and for about R400 you can have the comb chamber made the same as the gx.

Quote:
I am not planning on getting rid of it ever.It is stock standard and when tested it tested still fine.

My car also has a GX head but it has been skimmed previously due to blowing head gasket. This one I am planning on doing a little work on including the fitment of A14 valves.