what is the best 400 abc blocks

[mud slinger]

i know there is 3 diff kinds of blocks out there the 509 511 and 817...which one is the best?
we bought 2  511 block and both been crack between the the steam hole and head bolt hole...

[Jjay78]

the 511 blocks are the 4 bolt main blocks, the 509 blocks are the high nickel blocks and the 817 are the base blocks, the 511's tend to have issues with the main journels because of the additional main bolts, the 509's and 817's only have the cooling temperment with the steam holes being necessary in the heads...reguardless which block you choose you have to have the steam holes in the heads and in the gaskets or you'll just keep cracking your blocks and cylinders