429/460 casting flaws?

[averagef250]

Yesterday I dropped off a perfect looking DOVE 429 block at my machine shop for cleaning and a berry hone. The shop owner immediately told me the block was cracked and to find another one. Right behind #8 cylinder there was a 2" crack with rust around it. I had him mag the crack and trace it with a sharpie, figured it was worth a try to drill the ends, vee it out and braze it up. I took it back to my shop, drilled through the ends of the crack and found the rear of the block was only 1/16" thick! I pulled out a 70's truck 460 block I had sitting in the corner and looking it over found it cracked in the same place. I wasn't going to waste the energy trying to fix that block, but drilled through the iron where the crack was out of curiosity to find this block was also paper thin at the rear.

What gives here? Is this a really common problem with these engines? Are there any known early 429 block castings that do not have this problem?

[willowbilly3]

Dustin, can you show us a picture so we know what to look for. Apparently your machinist has seen it before.

[Dragon]

I had a friend that had a 70 Mustang 429 Semi Hemi that had way thicker walls than that. We cut the block apart when the engine blew at 9500 rpm to see what caused the black to fail and it was an oiling problem. Next engine did not ever come apart. NASCAR block.

When I worked for Ford the first time I saw very few 429/460s in trucks or cars in South Texas with minor problems mostly with carbs and Duraspark. The 2nd time at Ford we got two in the shop in 3 years and they had head problems so somewhere Ford fixed the problem. I always worked the Electric side and the Truck shop.