I was going to ask that question when I opened this thread. Can you put a 4.04 sleeve in a 318 block? Can you bore the sleeve to 4.07? Next question. Is it worth it? Bore helps a lot in the down force when adding more square inches of piston surface but we're talking a 4% increase in the 340 over the 318. Can we go directly across the board and say that the power gain is proportionate to the increase in surface area? If a 340 has a 4% larger bore than a 318 can we say that we get 4% more HP with all things being equal? That's a difference of 300 HP or 312HP respectively. Is it really worth it? Truth be told I've done my last 340. I'll save all the 340s I run across and sell them to someone that thinks they need a 340.
