Quote:
Originally Posted by bigjimzlll
400 blocks are notorious for cracking from the steam hole to the bolt hole(no big deal) or to the cylinder(bigger deal)
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Seen lots of 400 heads with cracks stemming from the steam hole.
If I was going to build a 400 block based motor, I would not run factory heads. They just don't have enough meat in the deck. I would get some aftermarket casting, such as Enginequest or the other brands out there that are heavy cast and have about a half inch of deck thickness. Drill the steamholes, bevel the edges of the holes slightly, then call it good.
As for the block, if you are planning on street use, it would be a good idea to drill out those steam holes.