Datsun Roadster Forum-311s.org

I have a cast iron R16 head with a 712 number cast into the top of the head. Anyone out there know anything about this one? For Datsun 1600 or could it be a forklift head? It has a 3 bolt thermostat housing if that helps. I bought it so long ago as a backup to my R16 aluminum head I can't remember the details. I've read on the site that the aluminum R16 head is the limiting factor for hp as it does not flow that well....

tia, Scott

Post a picture.
The early iron 1500 and 1600 heads are quite similar. I'm not sure how to distinguish the differences between the two.

" I've read on the site that the aluminum R16 head is the limiting factor for hp as it does not flow that well...."
Unless you intend to put a lot of money into the engine it will flow more than enough. I've looked at enough R16 heads to say that the differences are minimal, and the worst part of all of the heads is the exhaust valve and port. That goes for both iron and aluminum. Biggest difference is the later iron H20 head, which still needs a bigger exhaust valve and the exhaust port still isn't much, if any, better.

The R16 intake ports are actually quite good and will flow 160 - 165 cfm stock. All sources I've come accross point to a general 1 cfm = 1 hp potential for the intake.
The trick is to bring the rest of the system up to that potential, starting with the exhaust valve which is small, and the port which is quite restrictive right at the valve (throat) and around the valve stem, depending on your horsepower goals.
After the exhaust valve/port work, depending on your goals, you can work on the exhaust system (header) and carbs/intake to bring performance up.

There is NO R16/H20 head to 'bolt' on that will magically increase your available power without putting some time and money into it!
To 'top' it off, the H20 iron head will add about 20 lbs to the top of your engine vs the aluminum head. 20 lbs I, for one, will gladly pass on.

I see what you mean about tiny exhaust valve. How would you add a bigger one without enlarging the combustion chamber some?

Looks like a standard 1600 iron head....

"How would you add a bigger one without enlarging the combustion chamber some?"
No need to enlarge the chamber, valve won't get that big. First thing you should do is figure out a realistic power goal. 1600, 1800, or 2000?
Unless someone has some stashed somewhere, you will have to order custom valves. Maybe JT68 will have something for you.
If staying a 1600, I'm not sure I would go to a larger exhaust valve, maybe a 33mm. If going to 1800 33 or 34mm, or 2000, I would go to a 34mm.
It will need new hardened valve seats (intake and exhaust), and a good 3, 4, or 5 angle seat cut. Blend the bowls, clean up any casting flash.
DO NOT polish the intake port!

Thanks Daryl. If anyone would know it would be you with your stroker experience. I pulled my stroker engine in favor of a free, stock su U20. It has much more power than my 2L stroker according to my butt dyno. Nothing wrong with the stroker...it made 83 whp on a dynojet dyno. It's 30 over, pistons recommended by the machinist who did all the work on it including balancing everything. Stock R16 carbs, aluminum head. Head and block milled to aid squish. So this head appears to be good enough to spend some money on, or the aluminum head too I suppose, if I want more hp, but I think I'll just keep the assembly as is as a back up to the U20. Thanks again.