Originally Posted by Centerline
Not only do you have to have your crank done (as you would on most rebuilds) but you'll have to have the mains ground down to the correct size for the 400 block as well as the counter weights cut slightly for clearance. Then you'll need a set of aftermarket pistons. If you do the 440 you don't have the extra machine work on the crank and you can use stock HP pistons. You can figure doing the 451 stroker will cost you about $500 more for the short block than doing a 440. Don't get me wrong, a 451 is a great motor especially if your going racing but for street duty the 440 will be plenty powerful enough. Considering that a stock 440 back in the day cranked out around 375 hp, getting another 75 horses or so isn't all that difficult or expensive. A late 70's 400 will cost you a lot more to get to that 450 hp. mark since its stock hp was in the 190 range. Also just because your 440 came out of a van doesn't mean everything besides the block is scrap. It all depends on the heads. If they're 452 castings they'll be fine. The ONLY major components you'll need to replace will be pistons and those won't have to be anything special. Standard hp 440 pistons are capable of getting you to your goal with the proper cam, carburation and exhaust. It's your choice of course, just be prepared for the 451 to cost you a little more in machine work and a bit more for the correct pistons.
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Thanks for the explanation, that is definitely worth thinking about, especially if it isn't going to be any more HP. also I don't think the install into an A body is going to be that much more trouble for the 440 if I have to get headers anyways, I think its only a half inch difference in height on the motor and 40lbs. Maybe that money would be better suited to go towards some Ally heads later. I do have the 452's and I could get a port temp kit and do them myself for the meantime. Thanks again, I think you saved me a few bucks.