AC Pulley Size

[72911]

I am replacing all of the AC parts on my 72 and found a used dual pulley. It has a smaller diameter than the original single pulley. I was wondering if this was normal for all dual pulleys (AC pulleys). I'm not too concerned because the smaller diameter allows the fan to turn faster which can't be bad on an AC car. The timing marks are the same except for the 15 degree mark. Anyone have a belt size they want to share for this smaller pulley? Also maybe someone has a belt size that would go to the AC compressor? If my math is right it is just about 10% smaller.

[kuehl]

Originally Posted by 72911

the smaller diameter allows the fan to turn faster which can't be bad on an AC car

A smaller diameter drive pulley diameter causes the the driven pulley (compressor or fan) to turn slower.

The Factory PN for the 2 groove pulley is 911-102-015-50.
Typically the compressor belt groove these cast crank pulleys of this era were 4.5" nominal.

There are a few variations of these pulley's you can find from that time period, some have different mark locations, for example, for mechanical injection possibly. And, some of these early cast pulley's could be found on VW's.