Oct 2005
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57 McCulloch model numbers
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Has anyone ever figured out what the difference (if any) is between the VS57
and the OVS57?  I have one of both and the only difference I note is the OVS57
has a extra small nipple on the back cover that looks to fit a small tube. This
is in addition to the guage fitting that is on the outlet.  Is this a
difference or is my VS57 just missing the tube?  ANy other differences that
aren't apparent to the untrained eye?

Mike 

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VS 57 S would be the Golden Hawk version. VS 57 C was the kit contemporary. 
It was, I believe, available with both 6 and 12 volt solenoids. The 0 
prefix may indicate heavy springs or races with shims. 
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One theory is that the OVS57 variants are uprated.

McCulloch produced two different spring packs during 1957/58, the standard
and the heavy duty version. The heavy duty version was designed to allow
usage of the McCulloch on >300 Hp engines, or for draw race usage - I guess
it would be a precursor to the modern competition units. It's possible that
the O prefix applies to units with the uprated spring pack.

The only other differences I'm aware of between the VS57 units, apart from
the obvious 6V/12V solenoid, and the belt thickness for the Studebaker
(Packard?) units, is that some of the later VS57 units (cut off date and
year unknown) had heavier air psiton springs, and heavier idler springs -
presumably to reduce belt slippage. This may well have been a change used
for the OSV57 unit as well.

I have two units myself, an OVS57C and a VS57C. I really need to get around
to opening them both up (in a clean environment) so that I can see the
differences.

Jim 
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