I don't believe that it is a factory manifold. I am very familiar with the 1200 & the later A12 GX induction systems & the only other GX was the A14.
There is a factory GX manifold just up the road that is not a 1200 or A12 one so I presumed that it was an A14 item & yes, from memory it had 4 bolt carbs.
I will try to get a picture of it & post it here for comparison.

Thanks guys. Based on the A14 data, I was able to find all three in the parts catalog and make a comparison picture:


manifold comparo

Well strip my gears, I learn something new on this site every dang day.
No wonder it's so well designed, it's a factory item after all.
I'll just go over in this corner & have some more humble pie.

me too, I was trying to sell it, and realized it was not an A12GX manifold, then worried it was "just" an SU manifold. I'm glad to find out it is an actual factory Nissan manifold.

Better yet, it is for the A14 oval port -- not the monster A12GX port.

If you turn it around in another picture & provide the port dimention I believe that you will find out right quick.

Personally, I suspect that it is for the A14 Oval port head, but we shall see.

Do you have the carbs for it?

Already measured it -- this manifold is for A14 Oval Port head (mid-size oval).

Unfortunately I don't have carbs, which is why am agreeable to selling it. I started a wiki for it, with more details: wiki - Hitachi Twin Carb

David, watch for incoming PM.

I best check the twins that came off my A15 and see if they are simular..

Those coolant galleries, for manifold heat, come right out to the carbs. Are there any British SU carbs that use the coolant to heat the carbs themselves. This would be particularly usefull in really cold areas. This looks to be a fairly well thought out design.

My original A14 import motor had this setup... The hitachis had the 4 bolt flange...