Quote:
Originally Posted by CFMCNC
The standard V8 balancing formula is a bobweight consisting of 50% reciprocating weight and 100% of rotating weight,From expierence we will alter the reciprocating percentage,We have gone anywhere from 47% to 55%,Both underbalanced and overbalanced.Variables are stroke,rpm range-power curve, component weights ,crankshaft counterweight design and more.Bill C.
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Bill,
Gave good explaination,I'll add a little I think what is most important is to get a good balance job,I see balanced rotating assembly's people buy where pistons,rods never have been out of the box and unwrapped,rods still in sealed bags, they must use weight that is on box,which isn't always correct,3 grams here 2 there before you are done you end up with a bobweight that isn't very close to what it should be.
I have rebalanced several one guy just wanted to check,bobweight I would use was 6 grams lighter than they had used, spun crank rear needed 80+ grams added.
another one pistons needed fly cut so crank needed respun had to add weight to it,
which is opposite of what it should have been,anytime you lighten pistons,rods,etc and rebalance a crank you should have to remove weight from the counterweight area.
On the harley's you have to balance them to what rpm they will be ran @ % is changed
to match,they will only be balanced in certain RPM range like a single cylinder is
Mike Taylor 3601