Guest vodkaboy Posted May 1, 2003 Share Posted May 1, 2003 I have a '77 280Z that is bone stock, save for the suspension, which has only been slightly modified. I know that the later heads (like the ones on the 280) were lower compression, and were said to not flow as well, as well has being choked up with smog crap. Well, in oregon you need to keep all your smog crap on there (or at least make it look like its all on there), and you cannot switch from EFI to carburation. So my questions are these: can i switch to an earlier model head and still keep the same intake and exhaust manafolds? would i still be able to keep my smog crap intact? how hard would it become to pass smog (what should i expect to be higher?)? i really wish i could switch to carburation because the EFI on there right now is being quite a pain in the ass. any other things i should consider when thinking about making this run better/faster before a head swap? Quote Link to comment Share on other sites More sharing options...
Synlubes Posted May 1, 2003 Share Posted May 1, 2003 You could install a N42 head from 75 / 76 year model. The N42 head has square exhaust ports, but you can get an exhaust manifold from a yard and use your intake manifold you have now. The N42 head is a great all around head. Should give you a bit better performance than the N47 head on your car now. Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted May 1, 2003 Share Posted May 1, 2003 N42 and the N47 heads are the same except for the round ports and exhaust liners in the N47. There has been much discussion about the "evil exhaust liners" in the N47, but unless you are going all out race, then they won't make much difference and may even help with emissions. Really, to increase performance in the car , you need to raise compression. A set of flat top pistons from an 81-83 na 280zx in the set-up you have right now would do the trick, or locate the early 80's maxima N47 head, and that will do it too. Just swapping the N42 for the N47 will not do anything...'shrug'...except maybe make you switch exhaust manifolds. Quote Link to comment Share on other sites More sharing options...
Guest Venture-Z Posted May 2, 2003 Share Posted May 2, 2003 I just put the N-42 flat top setup in my car and it really screams. I run a holley 390, header, and a street cam, but the boost in compression will put a smile on your face. Quote Link to comment Share on other sites More sharing options...
Guest vodkaboy Posted May 3, 2003 Share Posted May 3, 2003 I just put the N-42 flat top setup in my car and it really screams. I run a holley 390, header, and a street cam, but the boost in compression will put a smile on your face. how much compression will that run you? what grade of fuel will you need to start running with that compression? 92 is really expensive here still, so i dont want to end up with any more than 89 for daily driving purposes (maybe when i go to the track i will put in 92 just to prevent detonation when im driving it like i want to kill it.) Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted May 4, 2003 Share Posted May 4, 2003 If all you want to run for fuel is 89 octane, then leave it alone. Or, you could sell it and buy a Honda. Quote Link to comment Share on other sites More sharing options...
Mudge Posted May 4, 2003 Share Posted May 4, 2003 Either leave the head alone, or pull timing if you need to, simple as that. Quote Link to comment Share on other sites More sharing options...
Guest vodkaboy Posted May 4, 2003 Share Posted May 4, 2003 mmhmm, i was hoping i wouldnt have to hear that, but oh well, i guess performance costs money. are any of the heads better flowing than others, but would keep the compression about the same (say, keeping the dished pistons, but taking advantage of better flow rather than better compression)? Quote Link to comment Share on other sites More sharing options...
Mudge Posted May 4, 2003 Share Posted May 4, 2003 Speed costs money, "How fast do you want to spend?" Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted May 4, 2003 Share Posted May 4, 2003 If all you want to run for fuel is 89 octane, then leave it alone. Or, you could sell it and buy a Honda. Quote Link to comment Share on other sites More sharing options...
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