This got me thinking. I have a 68 bird with a 69 400 engine. Its a YD code, which I looked up to find its a 290 HP with its original #46 heads. I was told the original block cracked and this one was swapped in, but the original 1968 #16 heads were reused. I am assuming that changes the HP rating, a block is a block right? If the bore and stroke are the same, its the heads that change the HP? That and its got a 4bbl on it, and hooked up to the original 4sp. Poor frankinstieny car O'mine. Block used to be a WQ. Any guesstimates on where that horse power might be after a block change but retaining the heads?
Not trying to steal your post flipbird...you just brought up a good point, and raised my own questions.
