> I have heard that these are kind of rare. I
> have one on my dads 71 and I have a spare
> just sitting on a shelf. Another thing can
> you tell me what # car they quit using E-31
E-31 is a non emissions friendly head, on production69-70 Z cars (when they were built, not when sold) It has smaller valves, and slightly higher compression than a newer z head. To that point the higher compression of this head, is set off by the lack of suffiecient breathing. The trick is to remill it, the e-31, and install stainless valves for the e88 head (the 280z) then you have the best of both worlds..