Valve size, N42 and N47 head....

[justaZcarguy]

Well here we are....

Tore the head down today with Phred, by the way thanks Mr. Phred, I learned a bunch today, I wish I had 10% of your knowledge.

So the plot thickens. Bent 4 exhausts and 1 intake. Ouch, but could have been MUCH worse, so if it had to happen, I'm thankful that it was minimal in comparison. The N42 had the bronze giudes replaced with steel, so that's good. But this makes me wonder if the valves are different from stock. They would most likely be different from the stock due to the guide upgrade?? (material wise...??) The dimensions are 1.385 on the exhaust head and 4.620 in lentgh, 1.740 on the intake valve head and 4.580 in length.

Now, the N47 was a steel guide head, does anyone know the dimensions of the valves in the N47? I would be surprised if the valves were as big but I also don't know if they aren't. The reason is for this question, I have access to a N47 head from a 810 (around '80). I'm pulling the motor tomorow, but thought I'd run the question by the professionals...:classic:

And, where can I get Nissan quality replacement valves to replace the ones that I bent? (Besides Nissan...)

Thanks guys, have a great night!!!!

~Brian

[2ManyZs]

As far as I know the valve diameter is the same in all the later heads. The late 74 260 E-88, N42, P79, P90 P90A all have the same diameter valves, the only difference is in the stem length. The P79-P90A have a stem length that is .080 difference from the E-88, N42, N47...Can't remember which ones are longer.....IIRC it the earlier heads that have the longer stems, but don't quote me on that.

You can get valves from MSA, VB and probably Nismoparts.com as well.

I don't know about the N47 head on any car other than the Z as to what they may have had as far as valve sizes etc....

One thing to consider is this, the N42 has square exhaust ports whereas the N47 has round ports... so if you are going to use the N47 you're gonna need another exhaust manifold...

If the N42 isn't in bad shape other than the bent valves and already has the steel valve seats, IMHO, I'd stick with that one you have since it doesn't need another manifold .....Just something to consider.

[Mudge]

Bronze valve guides are good, seats however not so much so. Generally you dont want the same types of metal in friction contact with each other, so I'm not sure how steel/steel will hold up under such friction/heat...?

[Phred]

Just a small correction on Brian's N-42 head. The valve guides are a cast iron alloy, which is what Datsun supplies with those heads. The seats are hard steel, not the Bronze alloy of earlier heads. What I don't know is when, and on what head # they started using hard seats.

Phred

[2ManyZs]

From what I have read, all the heads after the N-42 had steel seats.

And if you look at Bryan Little's site, according to testing, the N-47 actually has better exhaust flow characteristics than the square port head....and that is with the liner...

So if you have a manifold maybe you should go ahead with the N-47...

[justaZcarguy]

Thanks Phred for the correction, I think that is what I meant,,:tapemouth ...

I plan on using the existing head (N42), the car ran REALLY good with the existing setup so I do not want to change anything.

The question is what valves I have in the N42.

Thanks 2Many, I appreciate the information.....

Brian

[beandip]

dident you get my post about the importparts co. in Portland:finger: :

[justaZcarguy]

Yes sir I did, i am questioning the make of the valves, I want to match the stock part otherwise I am asking for premature wear....

Thanks for the info, they are the cheapest I have found so far, that's what worries me...

Also, I need to make sure that the valves are gonna match up.

B