I recently aquired a 70 240z. I know it has been tinkered on and its not stock. It has an E31 head (I know there rare,any info would help) and an N42block (was told it was a 260, I think its a 280 with that identifyer). I know the head is good to have although I don't know why. And I think that N42 means its an L28 block. Am I right???

It also has a 4bb holly, would I be better off rebuilding some su's until I can throw a tripple webber set up on it????

I am new to this, this is a hand me down project from my dad and he is no longer around, so now I have questions!!!

any info would be good!

Balaguy, the N42 is a block from a 280, so yes, it is a L28 block. Check the E31 head for cracks, for they were notorius for doing that, at least from what I understand from this website, or was it the E33? Any who, just save your money and go for the triple webbers or mikunis if your going that route, and you'd probably get better performance from the N42 head or the P90 IMO, for they breath better for either NA or turbo application.

Andrew,

People will generally put an E31 head (240 head) on an N42 block to increase compression however, the valve sizes are smaller on an E31 as compared to the N42 head, which have larger valves and a larger combustion chamber volume. Regarding carburation.....if you do not intend to use a larger cam profile and or addition performance engine mods, the SU's will work just fine and cost you much less to install than tripple webers. There are many posts regarding this subject, in the archives.

Tom

i would find out if you have dished or flat top pistons in the N42 block (my guess would be dished... rather silly for a "high-compression" combo). if I were you i would invest in some flat top pistons and an N42 head (good for 10:1) to get some flow, then worry about carburetion. stock SUs would work fine.

oh wait, that IS what i did.... plus a ~.500 lift ~.300 dur cam...