N47 Or E88?

[skinnyz]

Ok, I have just hit the jackpot...I am the parts manager at a Ford dealership, and we just acquired a Nissan dealership. They had more old parts than I can describe, and amongst them was a brand new N47 head. I am restoring (slowly, haha) a 73 model with an E88 head. I was about to send the engin out to be rebuilt next week, and need to know if the N47 head will work, and which head would be better to use. Should I reuse the E88, or go with the new N47? Also, I would like to know if anyone has any suggestions on which cam kit to put in. I have ordered from both Vic. British and Motorsport, and am looking for a new cam kit that will give me a good range, 1500-5000, with a fairly smooth idle, this is going to be a daily driver and dont want to go anything to crazy.

Also....if anyone is looking for any NOS parts, if you give me the part number, I can check and see if I have it...there is a bunch of stuff....some of which I have already got!

I appreciate any help you can give me!

[Arne]

Will, the N47 has bigger valves, which won't work with an L24 block unless the bores are notched for clearance, or it has been bored at least .040".

Other than that, I should think the N47 would be fine.

[WingZr0]

PM Sent....

[240ZMan]

Arne's points probably preclude using the N47 on your block, but in addition to that issue, the N47 has round exhaust ports and the E88 has square. I've read that it's no big deal to bolt a square port exhaust to a round port head (although the reverse is NOT ok), but if you're going for max performance, then I think you'd want to match exhaust and head port types.

Also, I believe the combustion chambers are a little bigger on the N47, so you might see a little drop in the compression ratio.

I think unless you plan to go more agressive with the cam and improve your intake and exhaust breathing, you'd be best staying with the E88.

[DaveN]

Re cam --

Good advice here: http://www.geocities.com/zgarage2001/engine.html

High lift, short duration for 1500-5000 RPM. Be careful to get the metallurgy right.

Re heads -- E88 to keep the compression ratio up.

[Carl Beck]

The E88 as used on the 73 240-z's had 47.8cc combustion chambers. The N47 has 44.6cc combustion chambers. So there would be no loss of compression ratio.

The E88 on the from 73 has very poor combustion chamber design as far a "performance" goes, although it's a good emissions head. As mentioned the N47 has larger intake and exhaust valves as well as hardened valve seats, but it too suffers from poor combustion chamber design.

The N47 will need to have its exhaust liners left out - and the exhaust ports need some porting work to open them up a bit.

If you go with the N47 - might as well add the crank from the 260/280... and pick up the extra stroke and added cc's.

FWIW,

Carl B.

[Walter Moore]

Will, the N47 has bigger valves, which won't work with an L24 block unless the bores are notched for clearance, or it has been bored at least .040".

Other than that, I should think the N47 would be fine.

Can someone explain this piece of wisdom to me?

I have read it several times, and don't know if I just got lucky, or if this is not true, or what.

I have an L24, and when I rebuilt my E31 head I had to have the original brass intake seats cut out and replaced with the larger 280Z intake valves. If I remember correctly the original valves were 42mm and the current intake valves are 44mm. My exhaust valves are 35mm I think. Anyway, I rebuilt the whole engine, but because the cylinders were still in specification I didn't have it bored out at all. The machine shop just honed the cylinders and I put it back together. I didn't notch the cylinders, pistons, or anything else.

It runs fine, and I haven't bent any valves that I know of. So when is it that the larger valves cause a problem? Is it just on the E88 head? Is it a stack-up thing that only affects certain engines? Or does it only appear later, after the engine begins to carbon up?

I don't understand.