Quote:
Originally Posted by 4Lowie
I was also looking for reasons why the flywheels are out of balance to start with! ... there must only be one way to fit it to the crank, (rotation) right?
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Yes, they index in only one spot due to a keyed locator on the balancer and unequal spacing of the flywheel bolts. To fully balance a crank internally would require larger diameter counterweights, expensive heavy metal or considerably more weight than 28.8 ounces on the counterweights. So, if you move some weight to the outside you save money and size or weight. The downside is extreme performance engines can suffer from harmonic crank stresses with external weights. Not something street engines and most weekend racers are in danger of.
Personally, I do not assume any balance factor on a stroker, as various combinations of parts can mean huge differences in balancing schemes. If you have a good relationship with your machinist/balancer, you can tell him the component weights of the parts you're planning to use and he will get a rough idea of the best way to balance it and what it might cost. I don't think I've ever had a 'stock' balance on my strokers. They always end-up at some weird number to get it right. That doesn't bother me at all. I don't change balancers or flywheels like tires.
I do know my daily driver 427W has a 34.4 ounce balance factor, and it's balanced to 1 gram along with the pulleys, pressure plate and disc, all index marked. If I ever need to change any parts I just take the old one in and have the new one match-balanced.
My balance guy is a wizard. A bit of a recluse, probably has OCD and is definitely anal. Just the right combination.
David
Here's a couple pistons from the 427 stroker - 7 of the pistons were machined to match weight to the lightest. The left one is lightened .8 gram and the other .5
And this was the heaviest, requiring removal from the piston crown and pin pad areas to lose 1.6 grams:
Today
