Heads
 

Alright everyone I got fed up with finding used heads and getting cracked ones so I decided to go with a used already rebuilt one... I emailed this guy about getting an N47 and he said that he has two different style N47's So i guess I was just wondering when did they put heart shaped valves on an N47 cuz this guy keeps tellin me they have oval and heart shaped ones but both are N47's I thought that the P79 and the P90's only had heart shaped valves. Here's te pictures he sent me.. he said they are both N47's...

I'm just guessing here, but I'd assume the heart shaped combustion chamber is from the 280zx and the round one is a 280Z. That head was used from 77-80. Either way, get the heart shaped one. It's a far supperior combustion chamber, hands down. Don't even bother with the round one.

well my head stock was the round one but I didn't think they put heart shaped combustion chambers on the n47. Will it function and bring the compression to the same as the stock on will?

So you've got an 79 or 80 right? It depends on the size of the combustin chamber. The heart shaped chambers that I know of were 53cc. Which I think is actually larger then previous models.So if you've got dished pistons (79-80) then it will actually bring c/r down. Not good for power. You could either have the head shaved to bring the volume down (just make sure valve interference isn't an issue) or change to flat top pistons. Either one would boost your power levels and potential. The easiest route would be to just use the round combustion chamber though. Depends on how much time and money you'll have. If you can afford it make the change to the heart shaped chamber with some flat top pistons.

What else has to be changed to use the heart shaped combustion chambers. I was jsut wondering cuz I used the engine builder and it said then47 would bring the c/r to 10.3:1 and I wanted it to stay about there would it if I used the heart shaped one cuz the more power the better. I'm not a real big fan of forced induction so I wanted it as high as I can get without bolt on's. I got flat top pistons and two cracked N47's so I just wanted to know if either one would be about the same, and I lookred at the picture of the one with the round combustion chamber and wuts up with that it looks like its been used and not rebuilt where as the other one looks shaved and like it has no valves in it.....

thanks

Yeah the round one looks like it came out of a junk yard right before he took the picture. If power is your only motivation then you can have the heart shaped one decked to lower compression. LIke I said though, just make sure to check for valve clearance. This really shouldn't be an issue since the pistons are flat and not domed. Also the head would not have to be shaved all that much. It all depends on the combustion chamber volume though. You'll have to ask him about that. He can easily measure it. I'm going based off the fact that the P79 was a 53cc combustion chamber and heart shaped. Also if you have him deck the head he will need to install shims in the cam towers depending on how far he decks it. Other wise the cam sprocket will sit too close to the crank sprocket. The easiest way to do that is to have him shave the head in a thickness that a shim is available in. Other than that, it'll just bolt right on. FIrst thing to do though is have him verify the combustion chamber volume. Then go from there to get your desired c/r. 10.3:1 with the heart shaped chamber is going to be more efficien than the 10.3:1 with the round chamber. Like I said, it's all in how much you're willing to spend. If you're just looking for a stock replacement, then the round one's for you.