Thanks to an eagle-eyed @rgalla9146 I discovered that the outer fan pulley on my build doesn't match the inner fan/pulley. I've been doing research trying to track down exactly what I need and I thought I'd document it here in case I miss something or if anyone else has options.

The pickle I found myself in is that my engine was a core and did not come with the fan/housing. Through the build I have sourced missing parts and always specified the year/motor I have, to try and avoid this.

Despite this, the fan I have and have assembled is a later version. The outer pulley and the crank pulley are the correct versions, but it's also more expensive and time-consuming to try and source and replace the fan.

I can source an outer fan pulley that matches the fan, but then the pulley size difference means that the standard belt lengths aren't right for the application.

Early - crank pulley 116mm, belt is 9.5mm wide x 710mm long
Late - crank pulley 127mm, belt is 9.5mm wide x 725mm long

I believe 76-77 was the changeover year.

Using the early, smaller, belt on my setup would end up slightly too big. Meaning reduced shims and earlier belt change intervals... if it would even work.

I'm looking at late crank pulley options, but as you can expect in the 6-cyl Porsche world, nothing is cheap.



So the question is, does anyone have first-hand experience using the late fan pulley with the early crank pully and a 710mm belt?

I have a bunch of fans and shrouds from our last parts purchase. If you tell me part numbers of what you need and I have them, I’ll make sure to price them so you can sell what you have now and at least break even.
Just let me know how I can help.

I would need 90110601003 but I don't know how you can tell them apart without measuring the 8-hole pattern.

Here's what I measured off my early outer pully. I think this hole pattern should line up with the inner fan/pulley.

This is the chart of all part combinations that were made.

Click to view attachment

A while back I tried some combo that gave more flow due to
a higher ratio, but right now I can't find info on which one it
was. I eventually went back to stock.

I just went through this with my 76 Carrera 3.0 conversion. Stick with 69-74 year versions. I'm sure Mark has some of those pulleys around. I've never seen a crank pulley wear out, and the upper pulleys last a long time. So used parts are suitable.

Just wanted to update this.

Replacing the pulleys at this point is easier than doing the fan. I purchased an 83mm (75+) fan outer pulley and tried it paired with the stock 110 crank pulley. Using a genuine Porsche 710mm belt I was able to juuuust get enough tension on the belt with all 6 shims outside. Not a good solution. I also tried a Continental belt and that was way loose, not even close to enough tension even though it was a 710.

So now I've ordered a 130mm crank pulley and two 725mm belts to match the fan. One belt for the motor and one for the tool kit.