Please Help,

I have just purchased a 74 nova and am getting alot of whinig out of the rear end. It has Richmond 4:11 gears in it which are louder than normal but the whining is much louder than it should be. The engine is rated at about 330-350 hp. My mechanic told me I need a 12 bolt rear end but a friend of mine said it was probably set up wrong. I don't want to put in a 12 bolt if I don't have to. Any suggestion would be great.

Thanks

check your pinion depth. If its to tight it will whine /growl.

It sounds like your Pinion to ring gear mesh isn't correct. This is usually
set by using a blueing compound on the gears to find exactly how they
are meshing together and then the mesh can be adjusted by installing
the proper thickness of shims to either side of your carrier, which either
holds the ring gear closer to the pinion or farther away, which ever is
needed. Your pinion is set by the amount of torque applied to the nut on
the pinion shaft which inter compresses the crush sleeve to the correct
length. This will cost a bit to get done but if you have much invested in
your rear end it's worth it. As for needing to swap for a 12 bolt, I don't
think it's necessary, I know guys with upwards of 500hp under the hood
and have no problem with the 10 bolt (as long as you have a decent
gear ratio, like 3.31:1 or better).