I wasn’t sure where to post this but the normal experts are typically in here so here goes…

my 1974 XJ12 has a ‘95 6 liter engine swap. The water pump started growling and I bought a new “V12” water pump from Moss. It came with a v-belt pulley. The stock ‘95 water pump has a multi rib belt.

can I swap the stock ribbed pulley onto new water pump easily? My stock ribbed belt water pump pulley has 4 bolts which I think held a mechanical fan (but I can’t remember) and I added some washer and nuts to those studs, not knowing if that is how the pulley is connected (being safe than sorry).

the other option would be to remove the stock air pump from the ‘95 engine (which doesn’t do anything other than serve as a belt tensioner for the water pump) and then fab up a v-belt tensioner and pulley assembly. But this would be much more work.

pics below

 

This is memory, hahaha, and a 75yo brain.

The V pulley should fit the pressed hub of the later pump.

BUT

I am unsure of the "depth" of the V casting cup of both, but you can measure that and space, or not space to suit.

This all from many, many years ago, when a 6ltr was shoehorned into a MK2.
Too many beers through the kidneys since then.

Hopefully others will have thoughts..

 

Grant you were right, thank you!

I pulled both pulleys with a puller and then heated original ribbed pulley a couple hundred degrees and slipped it on with a gentle nudge from the press. I think it may have bottomed out in the exactly right spot but I only pushed it until it got to the measurement I took off the original pump. 2 1/4” between a mounting bolt and the rear face of pulley for any future searchers.

and here’s a bonus video of my original water pump pulley. Crunchy. It’s sometimes hard to diagnosis a noise and that’s especially so on a car that you’ve changed so many things and so it was gratifying to hear this noise, knowing my diag was correct.