[steelcomp]

Sizzler,
I don't know where the quote came from, but I don't agree. I know there were some cases of block failure with SBChevs, and I don't think anyone here is trying to put down an engine design or trying to make this something personal, but I don't think the splayed bolts were designed to keep the block together. BUT, I could be wrong. There were four bolt SBC's long before there were splayed outers. The splayed outer bolt is used in other engines where there was never a "splitting" problem. It's just a better method.

The evidence of cap walk indicates that there is movement of the cap. Movement of the cap indicates that the bolts are stretching. Even at the micro amount they are stretching, they are stretching. When a bolt stretches, and returns, it will work harden and eventually break. The cap is also doing the same thing. If it is moving, it is "deflecting" ie: bending. It's like bending a piece of wire. It's why rod bolts fail. The first step is to install studs, which have a much higher clamping force, and resist stretching more that bolts. The next step was to install "more bolts". I've seen a lot of failed engines with broken bolts, blocks, caps, etc, and it's really hard to tell just exactly what failed first when you get a pile of junk. Did the bolts fail, to cause the block to crack or the cap to break? Did the cap break, causing the bolts to fail? I also know that for higher hp blown applications, cast caps are no longr strong enough. My observations and experiences have always led me to believe that the extra bolts were to add strength to the bottom end, not make up for a weak block. The splayed bolts really act more in the direction of the load than do the verticle bolts, but the concept of capturing the cap in two directions is what I believe the engineers were trying to accomplish in an attempt to minimize cap movement by increasing rigidity. The splayed bolt also helps move the secondary bolt hole further away from the primary main bolt, allowing for a more integral main web, and helps distribute the load more through the pan rail and side of the block, instead of just the main web itself. Rigidity is the key in every aspect of designing an engine, especially where the dynamic loads are so great and the more directions in which you can secure something like a main cap, the more rigid it will be.

The girdles on two bolt Ford bottom ends IMO are more a bandaid. The one on the FE does the same thing as the cross bolting. It helps transfer main cap movement to another rigid part of the block.They are an inexpensive way to add "some" rigidity to a two bolt bottom. There just isn't an inexpensive option for Fords when it comes to four bolt mains, or beefier parts. Roush offers (used to) a main support kit that is a bar that goes across the top of a cap, after machining, but that was another bandaid. I think more benefit came from switching to studs with the kit, than the bar itself. Tying the assembly together with a girdle helps distribute the load, much like a stud girdle on a cyl head, but you don't have the bending load on a bottom end like with rocker studs, so it's a weak comparison. They seem to have some benefit on bottom ends, but I wonder what the comparison would be without them. I can see a bigger benefit on the SB Ford, where their hp levels are far exceeding anything the blocks were designed to handle, but on the BBF I thnk they're a waste of time. KC might have some more "practical" input here, and I'd be interested in hearing what he has to say. I don't see in any way how the girdles can keep a block from "splitting". I see unitizing the main cap assembly, but again, more to minimize individual cap movement which can lead to bolt/stud failure.