wWl someone please tell me how the Alternator on my 1970 series 2 FHC ishould be driven?
A previous owner fitted an internally regulated American Alternator and there is just one belt that drives both the Alternator and the water pump. Is this correct or is the Alternator driven separately? There are two pulleys on the crankshaft, the smaller outer one is used at the moment. The inner one is much larger and it would really spin the alternator fast, maybe too fast. Is this larger pulley only for cars fitted with A/C?
My 69 has no AC and there are 2 belts:
- Crank to water pump (with jockey pulley to tension)
- Water pump to alternator
On my 71 the smaller pulley on the crank is used for the power steering pump.
Hey George…… you don’t happen to know the part number for that double pulley on the water pump by chance…. Is it a double V belt or a W belt
Cheers
D
Sorry, no part number but is is a simple V belt.
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Careful, there are many pulley/belt combinations. The bracket changed in 1970, and that changed the configuration. It’s also different when a/c or p/s are installed.But in all S2 configurations, there’s one belt for the pump and a second for the alternator The alternator may be driven by an intermediate pulley on the pump. And good luck finding pump pulleys.
It’s going to be much easier to engineer your own solution than to try to make it work with factory parts. The alternator pulley ratio should be about 2:1, relative to the crank, which gives you a redline alternator rpm around 10,000-12,000. If you have an intermediate pulley at the water pump, you have to multiply the pump/crank ratio by the alternator/pump ratio. If you aren’t in range with your present alternator and pump pulleys, your best bet may be to seek out a generic alternator pulley. Especially for a Delco alternator, a pulley will be easier to find than a double or triple Jaguar pump pulley with a custom ratio. Once you have set up a reasonable pulley ratio, use a string to measure belt ID and a good parts store should be able to find you a belt.
Thanks Mike…… I’m trying the new belt first, no doubt you read my “education” post recently …. Just musings at the moment …… plan c or d etc
Thanks for the information. Looks like getting hold of a double pulley for the water pump is impossible. I will measure the pulley on the crankshaft and work out the drive ratio but I suspect that it will be lower than 2:1 and getting a smaller pulley for the alternator will probably be difficult
Maybe I could use the big pulley on the crankshaft to drive the alternator. I will measure its size and work out the ratio
Post some photos of your pulleys, measurements too if you have them. Maybe we can figure something out.
Talk to Dick at Coventry Wrst about the pulley.
David Barnes my 1970 FHC is set up identical to your photo :-
Michael Frank supplied information on the “correct” water pump and alternator drives. There are supposed to be two belts one driving the water pump and one driving the alternator using a double pulley on the water pump. The double pulleys can be bought but they are expensive.
I don’t know why a previous owner of my car ditched the correct system for the single belt arrangement. My only concern with the single belt system is that the alternator is not being driven to slow or too fast. Michael suggested a ratio of 2:1. I still need to measure the diameter of the crankshaft pulley so I can calculate the ratio.
Thanks to all who replied
I’ll try to get under my car later and verify the pulley ratio.
It’s hard getting in there with everything in place, but my best measurement makes the overall ratio as 1.9. So the alternator has a speed of about 10,500 RPM at the redline.