On the left is a used pulley, part number 930 102 128 01. It measures 134mm diameter.
On the right, the darker color, is a brand new, $200, pulley of the same part number. It measures 132mm.
I am really looking forward to performing back-to-back tests of these pulleys against the stock pulleys on my '66 911 and '71 911E. I plan to take CHT and oil temperature measurements with a data logger, which will also record vehicle performance information, e.g. flexibility numbers, 20-50, 60-100 numbers.
