GM 400 sb casting help

Old 07-30-2007, 07:34 PM
Junior Member
Join Date: Feb 2004
Posts: 15
Default 400 block

Don't be to scared of that 2 bolt 400 block. I ran them in bracket cars and nitrous street cars for years with no problems the last one I had was a studed 2 bolt block with splayed caps ,filled to the freeze plugs . That motor was .040 over with a reworked stock 400 crank, aluminum rods ,14-1 ross pistons .227 afr heads, and a 2 5/16 hilborn stack injector on alcohol .
I ran 8.0 @160 with that motor in my 235" dragster and that motor went to 8600rpm on the burnout every pass with no problems to the block or crank.
blown375 is offline  
Old 07-31-2007, 07:41 AM
Join Date: Jun 2006
Location: The Custom Engine Shop, Indianapolis, Indiana
Posts: 73


Your goal are reasonable. The 400 will be ok.
Much of the stuff I build is for guys wanting much more!

Enjoy the ride and have fun. Invest in the cooling system like Brian suggested sometimes a 400 is a little tough to cool. Make sure you heads have steam holes it will help a street driven car stay cooler.
Robert1320 is offline  
Old 07-31-2007, 08:53 AM
Thread Starter
Join Date: Jun 2006
Location: Alger Mi.
Posts: 70

I want to thank everyone for your time and expert help, great bunch of guys thanks Cj
cj422 is offline  
Old 07-31-2007, 01:35 PM
Senior Member
Join Date: Nov 2003
Posts: 290

We machine a lot of blocks in our HAAS 4 Axis machining center and we have seen many problems with the 400 blocks with there thin decks thin webbing and with the big main line and big cylinders makes the webbing weaker the the 350 block and the bigger bores make for a weaker deck then the 350 block as well.

We have gotten far more emails and calls with problems with the 400 blocks.

Any block that comes through our shop is sonic tested and we have seen a few 400 blocks that were not safe for a high horse power application and we have a virgin 400 block that is cracked from the cam tunnel down to the mains.

Don't get me wrong we have machined a few 400 blocks and some have worked out well and some have failed or have developed cracks after a season of running.
hink is offline  
Old 08-13-2007, 06:01 AM
Junior Member
Join Date: Jul 2003
Posts: 3

you want the 509 casted block is the best...dont buy all the hype about the 400 blocks., they will work fine if properly prepared..ive ran them for years with no failures due to the block
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