Rolled fillet cranks

["Bruce Hevner" <scramblr@xxxxxxxxxxx>]

>Another question is of fillet rolling - something
>done to the Turbo Buick Grand National Crankshafts
>to ward off cracks forming.   As I understand - these
>filletts are rolled under high pressure during manufacturer -
>is it possible to do this to welded up cranks  and 
>cast crankshafts alike ?
Rolling the fillets is not done to prevent cracking although it does kinda
have that effect. It's done to increase the strength of the journal by
effectively increasing and smoothing the radius of the area where the
journal meets the crank itself AND compressing the metal at that point to
make it stronger. We have been told to NEVER grind a rolled radius crank
enough to remove (or even TOUCH) the radius. I believe the number given was
a 20% reduction in strength. This means most of these type cranks will only
grind .010 or .020 at most.
 There are MANY OE cranks besides the Buick that use this. The later model
Chebby cranks are rolled on the rear main only. I race a lot of Toyota 20r
series motors. The rods are rolled on all these motors from the factory.
 I have not seen this done in person but the pictures of the process I have
seen involve a LARGE hydraulic press with narrow steel wheels rolling the
journals of the crank. Not something the average shop could afford much less
an individual.
 We looked at having the cranks cryogenically treated to increase strength
but it was pretty costly so we never had it done.
 That is a REAL good indicator of quality in a crank grind. Forget the
finish (look at it second),,, look at the fillets first!! Look at the
fillets on a custom crank like COLA. They are large and smooth,,,
BEAUTIFUL!! Sometimes it is necessary to trim the edge of the bearing to
clear the radius on these cranks. 
 If the crank grinder is lazy or they don't own a radius dresser for their
machine, the radius will end up with a square corner. Do NOT accept a job
like this!! It's a stress riser that INVITES cracks!!. The radius MUST be
blended as perfectly as possible into the cheek of the crank. I have
magnafluxed cranks where the crack was on the SIDE of the radius. The radius
withstood the pressure but it was transferred to the mating line of the
radius to the crank. Strange pressures are at work here!!
But hey,,, that's just me!!
Bruce Hevner