I have to rebuild an engine and I have some decisions to make. I have a rather early 1970 240Z engine (it's a spare that I'm using as the foundation of my rebuild). I am on a 'no money' budget of course, who isn't these days. With that said, I want the most bang for my buck and am not out to build a monster engine...that will come later when I have the money to throw at an engine.

This engine has an E31 block and E31 head. I can do a stock rebuild on this and call it a day. Or I can pick up an N42 block locally for $50 (includes crank, pistons, rods all disassembled) and build from there.

The condition of any of these parts is a question mark. They may be fine, the either block may need bored out, or some parts may be scrap metal. I also understand that the head must be rebuilt replacing the brass valve seals with steel ones (if I recall correctly); this is not optional since the brass will not tolerate unleaded gas.

I have used a couple Z engine calculators to determine compression ratio. That's all well and good though this does not tell me what I'm interested in knowing. What kind of HP and torque can be expected from either of these...well mostly the latter since the former is a stock rebuild for the most part?

Aslo, is there anything else I should be considering?

WOW! Really? Nobody has any information on this? I figured someone here would have some numbers and thoughts on this...maybe I posted in the wrong forum to get the right people reading it. :disappoin

Lots of info using the Search......

http://www.classiczcars.com/forums/showthread.php?t=10521&highlight=block+head+combo

Lots of info using the Search......

http://www.classiczcars.com/forums/showthread.php?t=10521&highlight=block+head+combo

Yes, this is all information I have read before. Unfortunately what is discussed is all about the compression ratio and I'm asking for HP and torque numbers given two combinations. The engine calculators do not provide this information...I've already used 2 or 3 of them to check before posting here.