Best 350 OEM Block
 

Looking opinions on which casting is the best for a SBC 350.... Any insight would be greatly appreciated

Re: Best 350 OEM Block
 

The 010/020 castings have better webbing the K 010 blocks, Then they have to pass a sonic test.

Re: Best 350 OEM Block
 

Carl… We've found the "386" and "388" blocks to be good also. They are usually Early 1968-69 castings, prior to the "010". The early 1969-70 "010" are very solid also, and in most cases have a "K12" behind the passenger cylinder head at rear of block. Always consider core shift that is noticeable at cam tunnel, try and find a block that has the cam tunnel bored centred with the thrust flange. Good Luck…MB.

Re: Best 350 OEM Block
 

I should also add if you can find an 010/020 with 2482 on the center caps, Don't go by core shift as a sonic test is the only real way to tell if you have proper cylinder wall thickness.

I have about 40 blocks that show no core shift but have failed a sonic test and have seen many blocks that show a ton of core shift but the cylinders were fine. Most blocks I have failed is because of one thin cylinder.

Re: Best 350 OEM Block
 

What about the Bow tie blocks? Anyone found another manufacturer which is accepted ?

Re: Best 350 OEM Block
 

Does the Dart SHP meet the criteria ?

Re: Best 350 OEM Block
 

I got lucky and found a 660 block that caught my attention. That's a '68 large journal 250 or 275 horse 327. This one had the cam tunnel bored directly down the center of the cam boss. The lifters looked to be centerd in their bosses very well, and the casting just had a good visual appearance. I had it sonic tested and the results came back with all 8 cylinder bores very uniform in their thickness, and accurately located .Apparantly the thin wall casting tecniques didn't start until after then. It had to be line honed, and we gave it to Gregg Luneack for a bore hone and deck proceedure, and he asked me where I ever found such a good block. He wished he had it for his super stock car. I put it together, and it's the best 327 we've had yet.
Another unlikely casting I heard about was a 350 with the words HECHO IN MEXICO cast into the rear of the block. Apparently, it wasn't a thin wall block either,because that thing turned out one of the fastest super stock 350's around. The whole thing about building a killer race motor is the block. Good OEM ones are all 40 to 45 years old, so the search isn't getting any easier.

Re: Best 350 OEM Block
 

When sonic testing I have found the older blocks worse then the 80's and 90's blocks, There does not seem to be any difference in cylinder wall thickness between the older or newer blocks its just how the cylinder molds were placed during the casting process.

Like I have said I have a lot of blocks that show no core shift but fail a sonic test and some that show a lot of core shift but sonic test fine.

Rather then guess if its OK its always best to sonic and be sure.