Help with ID'ing a cracked SBC?

[nitetrain4590]

Hoping some savvy guys can help me out with this one. This is my SBC 355 for my 69 Chevelle that Im about to build up.
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I noticed a good amount of material taken out at the base of my 8th cylinder. I am making an assumption that the material was taken out for clearance of the 6.000 H-Beam Rods, but looking closer, there looks like there might be a hairline crack coming off of the notch. Regardless, the notch and crack are below the stroke line and don't come close to where the pistons travel. So here are my questions:

1. Is this a typical area to clearance for a 350, with a 3.48 stroke and 6" H-beam rods?
2. If this turns out to be a crack after magnafluxing it, can machine shops repair this damage or is it a crazy expense?
3. Could the crack have been caused by an improperly balanced rotating assembly?
4. Lastly, from anyones experience, what kind of power can I expect to get out of this engine with the following stuff:

010 Casting 350 block, 4 bolt mains, bored .030 over
Probe Forged pistons -4cc (10.4:1)
Eagle H Beam 6.000 rods
Scat Cast 9000 series Crank 3.48" stroke
World Products Sportsman II 200 cc Iron Heads with 64cc Chambers as cast
Comp Roller Rockers with Stainless Valves (2.02/1.6)
Haven't picked a cam yet, probably a Comp XE280ish...HR
Edelbrock RPM Air-Gap Intake
Either a Holley 750 or EZ-EFI system

Thanks for any help.

[Scott Parkhurst]

That notch looks like a rod whacked it already.

It can probably be saved, but that crack is real and would have to be stop-drilled, at least. I don't know how close you'd be to a water jacket there. It's probably not a problem, but I don't like it.

The 010 blocks are pretty common. The last 2 I've had were free (from pals, but still...). You should be able to find a nice rebuildable one for $50-$100.

As far as what caused it? Who knows. It depends how close the rod came to the bottom of the bore. With a 3.48 stroke, you should have had sufficient clearance, but maybe that wasn't the case. If you were stroking to 3.75, you'd have to notch it. I would not point to the balance job, though.

Your power is directly relevant to the cam you choose. A 10.4:1 383 could make anywhere from 425-550 peak hp depending on the cam and some other factors (like headers). A 10.4:1 355 is in a similar boat- you could see 375-515 hp depending on the cam/headers and some other stuff (ignition curve, chamber efficiency, coatings, etc.).

I'd suggest a fresh 010 block. You should be able to find one cheap and easy. Since you're rebuilding anyway, look into the longer-stroke crank. You can still use the 6-inch rods, but you'll need some different pistons. I'd look at a solid roller cam....I run Comp's 12-772-8 in my 383, and it's a killer. Check it out if you want to play hardball.

[Pro Stock]

Scott is probably right about the cause of the damage, the crack isn't bad and can be fixed by installing an IronTite plug at the end of the crack, as stated blocks are cheap but machine work isn't, personally I would use the block that you have unless there are other issues that need to be addressed. As for power your 355ci engine should make about 450HP at the flywheel with an intermediate grind cam, 750 carb and 1 5/8" header. I had a 355" with Camel back heads, competition valve job and port match with a mild Comp Cams hyd. cam, stock rockers and 10.0:1 compression that made 415HP on my dyno. Your heads and the extra compression should make a lot more HP than mine did.

[nitetrain4590]

Thanks guys, I appreciate the help and the recommendations....