Quote:
Originally posted by SFfiredog
TMan,
There are certain, I repeat CERTAIN 390 blocks that can be safely bored to standard (4.13) 428 size. There is a method of sizing drill bits between the cylinder walls inside the freeze plug holes that will provide you with block candidates to have sonic checked. The drill bit method is outlined on the FE Fourm. Do a search on that fourm. No matter what 390 block you choose to bore out it is STRONGLY recomended to have a sonic map of the cylinder walls performed. Everything else about the swap is a bolt in.
--Mike
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Well....
the 428 is usually externally balanced, but other than that it's all a bolt in.
But, you don't have to go out to the 428 bore to use the crank. And the longer stroke crank in a 390's bore, or even a 390+ bore is still a good thing. You don't say what use you're planning for this engine. You may find that once you swap cranks, you'll want new rods, then new pistons, and once you go to new pistons the actual final bore size becomes a seriously moot point. Do the sonic check on any 30+ year-old block. Then plan out your build taking into account your expected goals for the motor.
Good Luck