Technical SBC HEAD CRACKS?

Here’s a question for the SBC gurus. I got a 350 from a friend who said it started blowing white smoke out the exhaust so the obvious suspicion was a head gasket. When I got the heads off I found the gaskets were fine but four combustion chambers were a much different colour than the others. When I used a dye penetrant kit I discovered 1” cracks in each of the discoloured combustion chambers. These are 882 castings which, according to the web, are prone to cracking between the valve seats, but these ones are cracked on the floor of the chamber at the transition to the chamber wall right under the plug, and I couldn’t find any reference to this location for cracking in 882’s. These heads have been worked on (2.02/1.6 valves, big springs, seals) but the combustion chambers and ports are untouched. The engine is .030 over, flat tops, has a big hydraulic cam, good intake and carb but stock exhaust manifolds, and I don’t think it was driven hard. Overheated maybe? Comments? View attachment 6338729

 

just had a complete rebuild on my 350,heads had slight damage, machine shop
would not touch them, engine builder ordered Edelbrock Alum heads with roller rockers
sounds great and goes well

 

Show us the other three.

 

I think not certain some of the later 882 heads came with 2.02 valves.

There know to be crack prone and not that great compared to other options .

Is a odd place to crack

 

did you clean the red off before applying the white? looks more like residual red sitting in there.

 

The red was wiped off with a clean rag. The other affected chambers have the same cracks but other chambers have nothing.

 

You could take them to a shop that has a magnetic crack detector to have the test double checked.

I've crack checked hundreds of SBC heads and that is a very unusual spot for cracks. Maybe that head was frozen?

 

I think that's what I'll do. Shame to lose these, some good parts.

 

With all the problems & deficiencys associated with cast iron SBC heads plus the cost of refurbishing them , the affordable price & pluses known with aftermarket aluminum heads is foolish to ignore , 882 &993's are low compression lazy burn smogger heads , best left in the scrap pile , , IMO .

 

If you have the same crack in 3 or 4 of the cylinders on that head, chances are that they are due to a casting defect. The core that creates the internal cooling jackets may not have been positioned correctly, or moved as the molten iron flowed into the mold. Either way, that section probably got thin and could not hold up to the combustion stress. It would be fun to section the heads up with a band saw, just to see exactly what is going on. Beyond that, you have a nice boat anchor there.

 

I agree with the aluminum heads and that will be my choice when I build this thing. I'm going to practice my porting skills and tools on these ones and I might just cut one apart to satisfy my curiosity. Thanks everyone.

 

A repetitive problem in the same locations means core shift. The core is the internal shape of the water passages. Its not supposed to move in the casting process, but shift happens.

 

That's the benefit of new heads , they don't need any porting to be far superior to those iron boat anchors .

 

882 heads aren't bad for a cruiser engine, and can last forever. A lot of 882 heads are still on running engines including the 882's I've had on my later 350 in my '69 Suburban.
If those are indeed cracks, they are not where SBC heads generally crack at. I'd give them to a shop that can magnaflux them and be certain if they're truly cracked or not.

 

The old GM castings were heavy thick material . It just like everything else as it got newer the penny pinchers , cut cost with thin wall out of US castings