In a message dated 03/08/00 12:13:25 PM Pacific Daylight Time,
doddk@mossmotors.com writes:
> When drilling the oil feed to the starved rod journals, do you cross
> drill the mains from side to side first? Have you run into grooved main
> journals on the B?
>
> I had a crank done a number of years ago. If I remember the mains
> were drilled from side to side, the journals were grooved, then the oil
> feeds cut to the #2 and #3 rod journals from the #2 and #4 mains. The
crank
> was also nitrided.
It sounds like this was a non-factory item, but done according to gospel,
nonetheless. The factory used to have grooves bearings available, rather than
grooving the shaft itself, but these are long exhausted. I don't think that
they really need to be grooved if proper clearances are observed, but you
would want to check that advice with a current SCCA type in regard to really
high rpm use.
In the factory crank (I don't have the part number at the office), you will
see little brass plugs where the first drilling you refer to was done.
The 3 main crank doesn't need this treatment, but the downside of that is
that it is also less longitudinally stiff, and will eventually flex and break
if use to 7000 rpm for extended periods.
Most of the guys racing Bs now, and the few racing Twincams, use specially
fabricated forged cranks like the Moldex product. I still use some factory
competition cranks myself, but rarely exceed 7000 rpm unless exigent
circumstances prevail (like someone attempting to pass me on the last lap).
Bill
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