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Author Topic:   scat crank shaft for a 383
posted February 25, 2004 06:00 PM
I baught a 383 scat crank that said it was for a min. rod length 5.7 took it to the shop to get it balanced and it was a nightmair you have to buy one for a 5.7 rod or one for a 6.0 inch rod DONT BUY ONE THINKING IT WILL WORK IT WILL COST YOU MORE TO GET THE THING FIXED THAN IT IS WORTH. I WILL NEVER GET ANOTHER ONE. I just hope it last a long time after what it cost to balance it out

posted February 26, 2004 06:19 AM
that is quite common. because they are designed for a specific purpose they are not easily altered. the counterweights are sized and placed in the correct place to suit the need.
we have a scat 3.850 crank (for a 400) that is internally balanced. the counterweights wrap around the radius (circumference) of the crank further and are far heavier. this allows them to be balanced for various rod/piston weight combinations.
i would guess that the reason in cost so much to balance is that the material is far harder than a standard crank making it harder to drill (we had to use tungsten drill bits) and because you used a different rod than what it was designed for, a greater amount of material may have had to have been removed. balancing can sometimes be a painstakingly slow process (when done accurately) but is worthwhile.
you could have paid less and ended up with a balanced crank that wasn't really balanced.

posted February 26, 2004 11:09 AM
the cost shouldnt matter whether its cast iron or 4340. all the shops around here charge the same.

the price differance come in when you go from external to internal balance, or custom stuff that needs mallory metal.

i would guess that the piston/rod combo you picked out was heavier than the cranks specified bob weight, and that your shop needed to use mallory to balance it out.

next time i would pick a piston ad rod that will get you as close to the cranks bob weight as possible.



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