[steelcomp]

The cross bolt design was a compromise that the Ford engineers came up as the only practical way to strengthen the bottom end as they were adding more cubes and power to the FE. Remember, the first FE was a 352" two bolt main. Cross bolting hadn't even been thought of yet. The deep Y block design was a carry over from the 292/312.

A splayed bolt design is the best of both worlds as far as "four bolt mains" are concerned. The extra bolts were originally added more as a means of controlling cap walk at higher rpm, than to actually "strengthen" the bottom end. Most two bolt bottoms will take tons of HP if the rpms are kept to about 6000. The "cross bolt" design controls cap walk very effectively, but realy does nothing to strengthen the bottom end vertically. Bolts in shear have far less strength than bolts in tension, and there is no vertical indexing with the cross bolt design, so "cross bolting" adds very little to the vertical strength of the bottom end. (The cap can still move vertically in relation to the block) The splayed bottom end offers both the lateral retention and the added vertical strength of an extra main bolt, offering the best of both worlds. The ultimate block is the design with four vertical main bolts as well as a cross bolt design, which is what you'll see in the high hp drag racing blocks like the JP1, KB, and Rodeck blocks used in Top Fuel and Top Alcohol. They actually use two cross bolts on each side of the cap. I'm not sure, but I think the Ford Mod motor has a version of four mains and a cross bolt. That's stout!!

From a mfg standpoint, the deep skirt design has many benefits besides being stronger, which were taken into consideration when going to that design.