Yes, the keyway is consistent year to year. However, the position of the
timing marks on the steel pulley relative to the four bolt pattern can vary
even within a model year. Mazda must assemble the stamped steel pulley to the
hub and then mark the assembly. I don't know why they use an assymetrical
bolt pattern. Perhaps at one time they marked the pulleys individually prior
to assembling on the hubs. Perhaps they make the pattern assymetrical just to
assist in the reassembly of individual cars... But there is NO UNIFORM
LOCATION of the timing marks from pulley to pulley even within the same year.
The process is certainly curious, because I have seen many pulleys that are
marked rather similarly (probably within two degrees or so) and others that
are off by large and random amounts (over 100 degrees). I would guesstimate
that about 70% of the pulleys are marked in a manner that makes them appear
"interchangeable," whereas the other 30% are clearly far off the "mark."

Jon Lauter
Rotary Power Marine Corporation

 
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