We have already posted our intent to install A/C in our newly purchased 1960 MK2 3.8 4-sp with OD.

As part of our preparation and design, we have decided on adding a second pulley on the crank to drive the compressor. We have not been able to find an original (if it exists) 5" double v-belt pulley. So we will make our own.

We just bought this 5" v-belt pulley and intend to machine out the center so it can clean the crank nut, and drill the four holes to attach to the damper.




We do not have access to an extra crank pulley unless we take ours off. Not ready to do that yet. So are looking for the following dimensions if one has one off the car.
The bolt circle diameter and the diameter of the center hole.
Here is a photo of the stock pulley.



We intend to stack the second pulley on the first using slightly longer bolts.

Thanks
jjsandsms

 

The double groove belts only ever came in 4 lengths, the longest was part number C19524 which is 1010mm long. All the AC conversions I have seen use a seperate V belt, like you are proposing to use.

The diameter of the centre hole is 60.4mm and the bolt circle is 72.9mm. The 3.8 and 4.2 have different bolt circles ( the 4.2 is 79.05mm), however the 3.8 and the HE V12 have the same bolt circle. What you could do is buy the front pulley from a V12 and machine off two grooves and then you have a single groove pulley that is factory fit. Part number is C37892

A photo of a 3.8 damper, 3.8 double groove pulley and the V12 triple pulley.

 

Thanks for the info. I looked at the pulley you suggest and they are available (eBay) for around $150.

I paid $20 for the pulley I referenced, and both have to be machined. I do have a milling machine and a rotating table, so we can machine either one of them,.

With regard to the triple pulley C37892, why could I just machine off one of the pulleys on the triple and I would have the double of what I need?

So if I understand your reply, I will machine the center hole at 60.4mm. The bolt circle for the pulley on my 3.8L is 72.9 mm.

We will give it a try.

Thanks
jjsandsms

 

You could only machine off one groove, whatever you need to make it work.

You are correct on the centre hole and bolt circle.

Here is a pulley for $50: https://www.ebay.com/itm/37456321270...mis&media=COPY