You're right, Doug. The axis of the crank throw isn't changed if it is
ground to a smaller diameter; offset grinding does change the axis,
resulting in a different stroke length.
Regards, Neil Tucson, AZ
-----Original Message-----
From: owner-land-speed@autox.team.net
[mailto:owner-land-speed@autox.team.net] On Behalf Of Doug Odom
Sent: Wednesday, August 31, 2005 6:49 AM
To: Keith Turk
Cc: land-speed@autox.team.net
Subject: Re: Fw: Another Quirky Question - Re Certificaton.
Keith, Turning the crank only shortens the stroke if you offset grind
it. Example: Chevy 3.48 stroke with 2.100 rod journals, If you offset
grind it to 2" journals you could reduce the stroke .100 in theory. In
the real world the best you can do is .090 because you have to clean up
the outside of the stroke at least .005. I have done it to 3.40 before.
Some cranks are just not indexed prefect to get it any closer than
that. Doug Odom in big ditch
Keith Turk wrote:
>> The Good Dr Mayf..... I can't believe I'm asking this.... But have
>> you considered how much you decreased the displacement when you
>> cleaned up the crank?.... Think of it this way.... if you turned
>> the crank down say .010 , Wouldn't you have effectively decreased the
>> stroke by .005?
>>
>> Would that be enough to get you down to 305.999999.... 306.13 Vs
>> 305.999 isn't much... and maybe that's all it takes, my math says
>> 4.030 X 4.030 x 2.995 x 8 x .7854 =305.62 and that was with just
>> turning the crank .010
>>
>> Keith ( and that's way to much math for O'dark .030 ) or 0234hrs....
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