If any one knows the size of the pulley that is on the alternator shaft it would help. I can find the part number, but not the size. (Diameter and belt width)
This is a bump. I really need the C33985 specs. There is one on on SNG but it is almost $100 delivered.
Thanks
Awillie,
Hope this helps. Seems BUTEC madea special pulley to Jaguar Specs. You may find a Leece-Neville pulley on eBait that may work, you just have to do some hard searching and maybe add a little modification plus a spacer or two.
Here’s the data requested:
Pulley:
I.D: 7/8" (22.22mm) (0.875")
O.D: 2 3/4" (69.8mm) (2.75")
Belt Width: 3/8" (9.61mm) (37.85")
Thickness: 1 1/32" (26.14mm) (1.029")
Center to Center Belt Groove: 1/2" (12.69mm) (0.5")
Pulley Grooves: 2
Nut Recess: 37/128" (7.33mm) (0.2885")
Back Side Extension: 1/2" (12.69mm) (0.5")
In the past a set of “matched” belts was required. With the increase in precision manufacturing that is no longer the case.
The BUTEC alternator shaft is 7/8" and the nut requires a 15/16" socket for removal.
The last item, a spacer was placed behind the fan assembly. The spacer is:
Spacer
I.D. 7/8" (22.22mm) (0.875")
O.D.: 1 65/128" (38.23mm) (1.505")
Thickness: 13/32" (10.33mm) (0.407")
Key/Keyway: 5/32" (3.89mm) (0.153")
Happy Motoring,
Dick
'74 OTS
'99 XJR
1947 Stinson 108-1 “Voyager”
Thanks for the information. It is more complex than I thought. I will look at the Bay and Jaguar Heaven. I may have to buy a new one. I hope the spacer is easy to obtain. Thanks again
Dick,
I know this is over a year old, but then our cars are much older, and I am considering an uprated alternator for my SIII E Type to cope with fuel injection and Bosch cooling fans, so the dimensions of the pulley are of great interest to me right now. I have been taking careful measurements on my pulleys and the distance between the belts trying to arrive at the correct center to center belt groove dimension. My measurements look more like 0.490" after trying several different methods of measuring. So my question is how certain are you of the dimensions you posted? Was this info ever published anywhere?
Thanks
Steve,
A little late BUT… 0.490" What??? Are you talking about the Belt Width (outside)? Not sure what you are asking. Of course by now I’m sure you have determined what is needed for your reconfigured system.
NOTE: All dimensions listed were taken directly from an Original BUTEC alternator. I have four alternators and all dimensions were the same for all four…
Just curious.
Happy Trails, Dick
Hi Dick,
No, not belt width. What I was measuring was the distance between the 2 belts that are used to drive the alternator. In the end I went with a Wosp 100 something amp replacement, and that was over a year old from now, soooo . . . 
Hi Steve,
Good deal as long as it works!!! That’s all that matters. If you’ve added an alternator please document it with the cars paperwork. That will tell any future owner of the change(s) you made. Just hate trying to figure what the PO did!!! Ha Ha.
Thanks for getting back to the Forum.
Happy Trails,
Dick
I haven’t seen this before, but someone has come up with a replacement for Butecs:
150 amps??
To what end? Arc welding???
And here I thought the only problem was the price $$$$.
There is that…!!
But, as they say… the more you pay, the more it’s worth.
Future owner?!?! Over my dead body!! 
Price? You wanna talk price?
The link to the new alternator shows a price reduction from ÂŁ719 to ÂŁ611 to ÂŁ509 w/o VAT.
That exchanges to (using today’s rate of 1£ = $1.20) to . . . $865 to $735 to $613 (rounded).
SNG Barratt’s charges $523 to recondition your BUTEC and for this new Powerlite equivalent they are asking $1,157
Hi Steve,
My thought exactly!!! All the Jag’s I’ve owned over the years stating “I’ll never sell this one” only to succumb to a massive amount of $$$$$. This is my last one, '74 OTS, restoring to factory original (with a few minor non-viewable upgrades) so when I take my final flight West I hope it will stay in the family but who knows!!! Everything documented “just in case”… LOL
Cheers,
Dick
In a message dated 2/20/2023 11:37:37 AM Eastern Standard Time, noreply@jag-lovers.com writes:
Wow Craig,
Many reputable Starter/Alternator re-builders can beat both prices, even in today’s insane pricing world!!!
BUTEC is a very robust alternator (Prestolite design for ambulanaces & fire trucks) but, as with anything mechanical, requires periodic maintenance. The weak link was the R2/1 Voltage Regulator along with the Tri-Diode. The VR main transistor invariably would fail over time. Replacing it with a MIL-SPEC transistor vastly extended the life of the voltage regulator! Replacing it was a PITA!!! Also, Never leave home without a spare Voltage Regulator. A few other “spares” too but that’s for another time!!! Ha Ha Today’s electronic parts design/fabrication and lifespan are far superior to that of the 1970’'s. OPUS ignition too!
Happy Trails,
Dick