I have built several SB400s. And here is what I can offer.
First of all, yes, any day of the week a BB can be built that will be stronger than a SB, even a SB400. That understood, BB guys (I like BBs also), let's move on.
I, personally, prefer a 400 over a 350 or 383 any day. Why not take advantage of the extra 50 inches? If you have a good cooling system, over heating is not a problem. If you have a SB car to start with, the 400 is so much easier to go with because no changes are needed and you don't have to come up with BB brackets, shroud, etc. It just drops right in. Cracks? Maybe. But if the block that you have to start with is OK, then use it. I have seen, and I have used 400 blocks with 1 or more cracks between the headbolt hole and steam hole between cylinders (I have 2 in use right now with these cracks, and yes, I was afraid of them, at first, but not anymore). Now think about it, this crack is between 2 holes going into the water jacket and it is sealed off with the head gasket. On either a street, or moderate modified performance engine, I have never seen this crack cause or become a problem. Period. If the crack went between the steam hole and the cylinder, then you would have a problem.
Definitely go with the 350 5.7 rods, a 6in is even better. The ONLY thing I would ever use the short 400 rod for, would be in a low rpm HIGH TORQUE ONLY engine that would never see 4500-5000rpm. Such as a straight work horse tow vehicle.
Pistons. I have used KB in one engine, no more. The KBs require a very big top ring gap in proportion to the bore. They provide a chart. On a 4.155 bore you can get up to a .026-.030gap real quick! I have switched to Federal Mogul hypereutectic which use a normal top ring gap. I personally called and talked to thier engineer about this and he emphatically assured me that was correct. The 400 with the KB/big gap uses more oil than the ones with the FM/normal gap. And, also, the FM pistons are about 1/2 the price of KB. I use the pistons with small dish, and depending on type of head used, this provides 9.5-10.2 compression. I have one 400 that I have bored/stroked to 420 with these pistons, no problems so far.
As far as 2/4bolt blocks goes, a 2bolt will live with any street engine, 350 or 400. All my 400s are 4bolt and I have changed my thinking. My next 400 will be a 2bolt ONLY, with either studs rather than bolts, or splayed aftermarket 4bolt caps. On a factory 4bolt 400 block, the outer bolt holes are into a thin area of the main webbing. So, if splayed caps were added, it would put the outer bolts over into a thicker part of the block.
Heads. I have used stock 2.02, Dart sportsman and Trick Flow. Remember the key thing that makes a BB better over a SB is because IT CAN FLOW MORE AIR! Therefore, you can't have ports that are too big on a SB400. Select a head with the biggest ports you can find. My SB420 is the one that has the Trick Flow heads, specifically because of the tilted intake valve which should unshroud the valve more, thus, theoretically, better flow. That is a strong engine! If you DO go with Trick Flow, READ THE INSTRUCTIONS FIRST! USE THE HEAD BOLTS AND HEAD GASKETS THAT ARE RECOMMENDED! And you won't have any problems. If you want cast iron, then the Dart Sportsman is probably as good as there is.
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[This message has been edited by DZAUTO (edited 07-13-99).]
