390 real hp isn't gonna happen easily with a 318 without using 340 heads, and the 340 rods are so much stronger that it makes little sense to use the small 318 rods on a motor you'll need to rev to make power with, so if you end up with a 318 with 340 parts in it you're better off just building the 340 you took the parts from cause you won't have to spend extra $$ to balance it. Even the good SB rods they now sell are all 340 type rods, so why spend almost the same amount to rebuild weaker 318 rods?
Why invest money in a motor that has less cubes and less internal strength than a 340 or 360? That's like building a 361 BB instead of a 383 or 440. Their are plenty of 360's around for the same price a 318 costs (motor core AND parts) and you have 42 more cubes to start with. Everything costing about the same I'll always opt for the extra cubes and hp at a lower RPM. That being said, a 390hp 318 in a average weight E-body better be doing about 110mph in the 1/4 mile, or the only 390hp it has is "theoretical".
