Can you post a picture of your cyl. head showing the passageway you are referring to?

Not sure if this will help, but check out Info required re A12 Gx Head

I do indeed mean the face. Duuhh should have mentuioned this. After looking at it last night it appears to be a cooling passage. Question still is does this need to be drilled out to match the deck on the GX block???


Tom

Or do you mean it is on the combustion face? There's as small one here between 2 and 3:



1234

Here's the matching hole on the A12 block:



502

A12 GX Head

This one only has the intake water holes under two of the intake ports:


469

I believe this hole is for coolant through the intake manifold. All the stock GX (SU) intake manifolds had water/coolant circulating through the intake. I guess it's supposed to help regulate temps, but I always thought it would heat the intake up too much. You should be able to tap and plug this hole. Pictures would help give a positive identification of what this hole exactly is though.

Ok I was looking at the H-production head as Nismo calls it and noticed a hole plugged that wasn't plugged on the GX head. The hole is on the manifold side in between #2 and # 3 combustion chambers. It is about 3 mm in diameter looks like an oil gallery. If I bolt the H-prod head on the GX block do you need top drill out this hole??? can the whole be drilled???

Tom