Quote:
ddgonzal wrote:
Ok, so I am not an expert on this. But my understanding - which may be right or wrong -
Fact: the Chevy V8 was designed in the early 1950s. First was the 4.4 liter version in 1955.
Guess: It was probably designed for about 5,000 rpm tops.
To spin faster with later versions, say as with the 5.0 liter of 1967 that revved to (supposedly) over 6,000 rpm, they added 4-bolt mains to keep the flex of the crankshaft under control.
In no way does this mean the original design was "bad", only that it was not designed for high-rpm usage. Previous to the 4-bolt mains Chevy smallblocks put out more torque but didn't use 4-bolt main.
So I think torque is not the factor, it is RPM.
The second V8 Chev design was produced in 1955 & displaced 265 cubic inches [4,343cc] & the main bearings, all 5 of them, did a good job, but the design was eventually expanded out to 350 cubic inches [5735cc] & used in larger trucks. At this point, the constant high levels of output in a heavily loaded truck meant that the company upgraded to a 4 bolt bearing cap design.
As far as I know, passenger models never got the 4 bolt blocks.
Datsun A series with 5 mains & 4 cylinders do not usually need a 4 bolt upgrade, even in the 10,000 rpm engines used in Formula Pacific & F3 racing.
Transfer
