I read in the HP book that the early 4 bolt engines used a higher nickle content even though they were cast in the same molds and the main caps were better but these were 68-72 is my understanding. I went thru 5 blocks to find one not cracked or that would take a .060 bore with out shadows, they are just getting old and worn out. I agree that ARP studs rule and spending the money at a good machine shop getting it decked, align honed and bored with a deck plate is the way to go. Just got one out of Brand Engineering here in OKC this week. All the above and balanced for a good rebuild. Good luck.
I am not a Chevy guy but It was passed to me that if you were thrashing a 4 speed car it was better to have a 4 bolt main because of the loading and unloading of the crank when you launched or shifted. If you were using a Slushbox then it was not so important as the automatic and torque converter kept the crank loaded all the time.
I understand their reasoning, but generally speaking, excessive thrust bearing clearance, among other things, would have more of an effect than how many bolts are holding the cap on...just too many variables to make a blanket statement. OE 4-bolt Cleveland blocks have such thin outer caps that the bolts are just about worthless, IMHO. However, they seem to survive rpm and 4-speeds just fine...as do the 2-bolt blocks. I still think that more performance engines are likely killed by detonation than by a main cap material failure.
I guess I'll explain further. I have been oogling this one and I am trying to weigh out all the options. New vs machine shop cost etc. http://www.speedwaymotors.com/Dart-Special-High-Performance-Blocks,9857.html
Well, next time we go by Brand we will say howdy! I have been using him for 20 years and very happy with the work.
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