The deeper you get into your GMC, the more apparent it will be that it's a commercial engine- - - -designed to work hard all day, every day, and be rebuilt several times before it's scrapped. As mentioned above, the connecting rods are much stronger, and they're drilled their full length where the wrist pins get pressurized oil. The rods also have replaceable big end bearings, and bushed pin ends, which can only be accomplished with a pressurized crankshaft. The oil pump is at least twice the capacity of a Chevy pump. Ditto for pistons- - - -bigger, and heavier built. The cylinder head is better-designed, with bigger and less-restrictive ports. Chevy got pretty close with the 261, but they pretty much maxed out the design that began with the old 194 engine in 1929. GMC got over 100 cubic inches bigger with the 302, something the 216/235 design couldn't even approach.
Jerry
