Maxima N47 on a 280Z

[Guest Anonymous]

Yesterday at the half price day at pick n pull I bought a Maxima N47 and the exhaust manifold to go with it. Together it came to 58 bucks! My plan is to use it on the motor I am building for my 76 280Z. I'll probably use the dished pistons that came with my 76. If I am not mistaken, It should be a good setup. I've read that the Maxima N47 as opposed to the Z N47 has a slightly smaller chamber, 40 cc's, which, in combination with the dished pistons should be a good deal. Does a CR of 9.08:1 seem right? I used the L Engine Program. Also, how neccesary is it to put larger valves in the N47. Will I notice any increase in performance if I don't? And finally, all of this should pass California smog, right? The other option would be to use flat tops and a thicker head gasket. Please tell me what you think about this. I was refered here by someone who said there was lots of info on this subject. Thank you. -wiskman

[ninja240z]

This should be a match made in heaven ,but make sure that head is in good condition before installing it. I bought a n47 maxima head and put it on a L24 with flat top pistons worked fine except that it was supposed to be rebuilt. One the valve guides was broken. I only found this out after I installed it and wondered why the #5 cylinder was not firing. I have heard that this head flows decent because it was a fuel injected head and that was made for unleaded gas unlike the E31 and E88 both having smaller combustion chambers and being made for leaded gas.

[DAW]

I'd opt for a factory OEM cyl head in good used condition anyday over a rebuilt cyl head; at least you know the geometry is as-engineered and designed...a rebuilt unit is only as good as the replacement components and the rebuild technician, both of which are often inferior to Nissan factory production.

 

I think you're making a good move with the head you picked up. For best performance on an L28, have the intake valve seats replaced with new L28 ('75-'78) seats, and take the intake valves out of the L28 head you removed from the dished-top piston engine and have them ground or lapped to the new seats. Transfer the L28 intake valve springs also to the Maxima head. Transfer the L28 cam, rockers, and lash pads to the Maxima head and keep them in the order they were with respect to L28 cam. If your L28 head is an N42 ('75-'76) then you'll need to transfer the cam towers too because they are spray bar-type cam oiling and matched to the undrilled cam. (later L28 cyl heads (and Maxima L24) have camshaft-drilled oiling; no spray bar).

 

You should be able to leave the Maxima exhaust valve (including valvesprings) as-is. Providing there aren't definite signs of a burnt ex valve, just leave them alone. If you're shopping for a machine shop to do the intake valve job only, and you find a machinist who can't comprehend what it is you're doing and for what reason, and tells you that he will only do a complete head rebuild, then walk away and find one who will. The first guy is also the type who will sell you additional "necessary" parts&labor once he has the head torn down.

 

This is not a complicated swap and you will definitely notice increased performance. Leave the dished-top shortblock alone and use the Maxima cast-iron exhaust manifold (as you're planning) instead of the 280Z manifold when you reassemble. Good Luck! DAW

[Guest Anonymous]

Wow, Thanks for all that excellent information! I have found a machine shop who specializes in L series heads and I plan to see him soon. I can't wait to get everything going again.

 

-wiskman

76 280Z