Early 4.2 Alternator Pulley and Fan

This is my original (I believe) alternator fan and pulley. The pulley has a mystery material bonded to it that matches the dish in the fan. Does anyone know if this is stock and if the material is meant to be a bonding agent/filler between the fan and pulley or a cushion or a dampener or…?

Rick OBrien
65 FHC in FL (very early 4.2)

I’ve not seen that before. To be fair, I haven’t noticed that the centre of the fan is dished, either.

I suppose it could act to stop any vibration of the fan. I can’t see any harm in leaving it there.

I am perplexed by why it is there. The woodruff key stops rotation so it is just a matter of torquing the nut holding it.

It looks like bondo who knows what’s been done
Probably not the correct pulley that’s been jury rigged and the fan isn’t dished Imo

There are two mentions of dished Lucas fans in this thread. So I’m not sure. The alignment is perfect. The material is somewhat fibrous, a little like gasket material.

“If concentricity is causing the fan interference, I’m not sure how I could fix that. I can’t use the substitute fan from my rebuilder, because note how the Lucas fan is dished in the center. This gives extra clearance for the fan tips, whereas the flat “conventional” fan scrapes the body.”

“Thought just came to me - if 15mm fans are very common for Lucas alternators, maybe I could use a fan for some other Lucas model instead. Many seem to have the dished center, which I’m thinking is important to maintain proper pulley alignment?”


That was me in the quoted thread. My (presumably original) 4.2 (S1) pulley doesn’t have that filler material, nor does the reproduction one I bought last year.

The fan (at least mine) is absolutely dished - otherwise the fan blades would scrape the alternator body (which is how I discovered all this when the fan keyway wore out. Luckily my fan has two of them, so I could use the opposite one that was unworn. Not all the Lucas fans have two keyslots for the Woodruff key.

I don’t know why that material is on the pulley, if it’s not factory. There is no issue that I can detect on mine where it is necessary. Maybe there was a belt alignment issue and that’s a substitute for a shim to line the pulley up?