"JR NORTH" wrote in message
...
4 bolt main caps truss the webbing in the block and reduce flexing under
extreme torque and rapid RPM changes, as in bracket racing. Little
positive effects in a marine type operating environment.
JR

bob wrote:
I may be replacing the 5.7L Mercruiser (Chevy) so am trying to get ahead
and
ask some questions early. I understand that a 4 bolt block is stronger,
but if
you build a 300hp (or less) motor, will it really make any difference?
At what
point do you see a 2 bolt block breaking (what HP)? Will a 2 bolt go up
to
350hp and hold up? If I indeed need to replace the motor, I plan to
look for
an automotive short block and install a marine cam, use all of the
mercruiser
other parts (manifolds, distributor, starter, alternator, etc.) so I
should
pretty much have a "marine" engine but not at the prices Mercruiser
wants.

Thanks,
bobby
bbusselman at hotmail dot com



Actually they will help in any marine setup. The webs between the mains are
thicker and stop flexing of the block. You still run marine motors at a lot
average RPM than a car motor. They blocks are not much different in price
from a wrecker. Most of the motors of the last few years are 4 bolt mains.
Bill