<VV> Re: VirtualVairs Digest, Vol 2, Issue 183

[djtcz at comcast.net]

I'm suprised it didn't turn smooth with 0.004 inch runout.
I think at one time Chevy's spec for a Tufftrided V-8 cranks was as much as 0.007 inch.

Kind of makes me wonder how round the journals were.
Straightening Tufftrided cranks with a press is risky.  Better is to peen the radiuses in the non-overlap areas with a contoured chisel.


> 
> Stephen, 
>  The plastigage goes on the bearing surface on the width IMHO. However,
> I have very recent personal experience with using only plastigage in one
> place per journal. When the block was separated. The plastigage
> indicated I had virtually perfect clearances with the newly turned .010
> crankshaft and .010 over bearings. This was just Murphy's Law!!!
> 
>  HOWEVER, when I reassembled the engine, the crank shaft would NOT turn
> 360 degrees by hand, but got hung up after about 270 degrees. Cutting to
> the chase... the newly turned and nitrated crank had bowed during the
> heat treat process resulting in the following journal runouts #1 .001.
> #2 .003. #3 .004. #4 .001. I could actually see the runout while
> rotating it in one crankcase half, now that I had a clue what to look
> for.
> 
>  I suggest that plastigage be placed on each bearing half at least two
> places 90 degrees apart. You can hold it in with a dab of oil/grease.
> When checked, they should be virtually identical widths.
> 
>  The problem was solved with a replacement .010 crank that would turn
> flawlessly.  Always remember to use lots of lube on the cam journals and
> bearing journals before the final assy. I like to use a mixture of moly
> disulfide and STP.
> 
>  Anybody else have better ideas / comments??????
>