New Zealand Datsun Club

I've got a real hassle here, the gasket has now failed twice and is leaking out the bottom of the exhaust ports past the gasket. After the first failure I got the exhaust manifold surfaced as it was a little out of true against a straightedge. I then used a gasket from APPCO and installed it dry. This began leaking after just a few hundred km.

What do I do, experts? Do I need a genuine gasket which looks thicker than the APPCO one including the reinforcing around the exhaust port holes. And, what sealant do you recommend, bearing in mind both inlet and exhaust ports are mating onto the same gasket including water port holes for the inlet manifold.

Next question is where can I find said gasket, in NZ or do I get one from Oz or the US, or eBay?

I'm keen to get the car up and running over summer after sitting for a little while now, about nine months!

I only ever use high temp. RTV ( silicon ) on the A series and have never had an issue. That's all my engine builder uses on the BDA Escort engines that he build and it would be extremely rare to see one of those fail.
Just make sure that everything is super clean.

Even a cheap gasket should be ok. In my experience the leaks usually arise from having aftermarket intake or exhaust manifolds with different thicknesses/contact areas on the spreader washers. I made stepped washers once to try to resolve it. Are you running a header or side draught manifold?

Other things to do:

-Replace the bolts at the top with studs, and use new studs everywhere else. Often they get bent.
-Make sure all of your spreader washers have a good contact on the flanges, and the flange thicknesses are the same
-Tighten the nuts from the inside working out, like when torquing a head
-Sometimes I find the flanges get a bit eroded from gas leakage, a tiny bit of high temp RTV helps there