ok if I have read everything on this website correctly , the 280z valves go into an e31 head with no prob and give it better flow correct? I will have to replace the seats to allow for the larger valves I assume, gonna ask the machine shop to do that , any significant advantage to using stainless valves <nismo> as opposed to stock , gonin nuts with this rebuild , thanks jeff:geek:

You might also have to replace the valve guides to match the valve stem.

ahh didn't think about that very good point , i just checked and all the guides are the same for 70-78 , kinda a concern now with mixing up parts from diffrent years , thank you I will add that to my grocery list

You will also have to check your contact patch on the rockers when it is finished to make sure the correct lash pads are installed.....

IIRC, the valve stem lenght of the 280 valves is not exactly the same as the 240 valves, so different lash pads will more than likely have to be used to correct the cam lobe/rocker arm geometry..I know I've got the lenghts around here to be precise, but I'm quite sure the 280 valve stem lenght is a bit longer if I'm not mistaken...

There's a long thread somewhere detailing the proper contact patch and lash pads thicknesses etc...

Here's the thread....

http://www.classiczcars.com/forums/showthread.php?s=&threadid=6342&highlight=Lash+pads

is that an issue if I will be replacing cam , rockers,springs and lash pads?

after reading that thread I answered my own question , now I wonder if who I buy the cam through would have the appropiate thickness lash pads if I told them that I was using 280 valves in an e31 head? would be to good to be true I bet