Is my SBC 400 block cracked???'s


G-Body Guru
Thread starter
May 6, 2009
Ok block off port for heatercore on top off waterpump and attach shop vac to big end of waterpump where the radiator hose would go,does the intake gave to be installed?Thanks


Comic Book Super Hero
Jun 15, 2012
Florida Beach
I was assuming since you ran it on the stand the intake manifold was on the engine.. yes it would have to be on it. Or tape off the ports on the heads really well.


Goat Herder
Supporting Member
Dec 1, 2014
Upstate NY
Bigger head bolts haha.

That looks cracked to me, but the proof is in the puddin’- put water in it and use some dye in the water (Easter egg dye is my favorite) and see what happens.

What do you have to lose? It can welded or locked and stitched, but that’s a full tear down. At that point, you might as well find another block.


Feb 18, 2014
Where the hell am im going to find another sbc 400 block LOL
There's a dressed up (dual quad, aluminum valve cover etc etc) job near you in Canton, but, they want normal money for it probably $2k takes it.

More budget friendly is the guy in Florida selling a stock 1972 511 casting thats carb to pan with transmission included for $1k, probably takes $800.

They're out there if you look


Feb 18, 2014
send links please

Also, fwiw, you probably already know this, but, the other option is have the mains ground on the 400 crank, use the flywheel/balancer from the 400, and stuff it into a generic cheap 010 350 block. That's how the 383s are made. Yes, the 350 would need to be clearanced for the stroke as well, but, you've got most of the parts there to build one.

And it wouldn't all be downside. You lost 17ci on the 400, but gained 33ci on the 350. Extra power at higher rpm, and, can get 4 bolt mains instead of 2bolts in the 400.

So, it'd be another way of making the best of a bad situation.


Aug 8, 2011
you probably already know this, but, the other option is have the mains ground on the 400 crank,
It's probably more cost effective to just buy a new stroker crankshaft for a 350, they run about $275 for either 1 or 2 piece rear main blocks

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