400 Block Question??????????????????

[Mod66x]

Had to remove my heads(leaking valve & blown head gasket between 4&6). I noticed on the block(stock 400 block) where the steam holes are that there's a crack in between the steam hole and the bolt hole(also between 4&6) both top and bottom, Question is will this cause a problem are is this the norm. Left bank isn't doing this. Can this be fixed or what should 1 do? Thanks in advance....

[willyj]

Google search the topic and you will get some hod rod forums. I think most will say use studs and run it. Our 400 did the same,but also cracked into the cyl.Most say to pipe plug the holes and drill smaller ones,then machine flat. I think some even pin the small hole. good luck in the repair. these things are notorius for this,I will never use a Gm block for mod racing again.

[stock car driver]

That doesnt happen if you plug the steam holes BEFORE you machine and deck the block.

Now that its after and already cracked I would junk it and do a new block, but thats me. I tow too far for a dnf etc.

[willyj]

Yeah scd is correct,i was a lil unclear in my post. The repair Now will be to use studs and hope for the best. Also agree with scd we junked ours and using a SHP now. Last i will say some have got lots of use from blocks with this condition.

[Egoracing]

That doesnt happen if you plug the steam holes BEFORE you machine and deck the block.

Now that its after and already cracked I would junk it and do a new block, but thats me. I tow too far for a dnf etc.

Agree, once they start cracking they will usually continue. It you run a claimer class it may be worth a try but the best would be replace it.

[parrot69777]

SCD hit it right on the head. Too many people think there is no point to plugging the holes and prepping a 400 block the correct way (have read it many times here on this forum). Then they want to know why things are cracking after the fact.

As long as the cracks go from a steam hole to a head bolt hole....just plug them and deck the block. If they go any where else (steam hole to cyl, steam hole to water jacket, or steam hole to steam hole) your just wasting your time.