Alternators - I have questions

[tluchette69]

My built mid year 69 Series IIA has a Lucas 11AC alternator and the fan and pulley are shot. I bought a new set but both are smaller than what I took off. New pulley is 64mm vs the old at 80mm. The new fan looks like a typical fan while the old one has a disc welded to it and is painted black. I read that there was a short period when LR was transitioning from dynamo to alternator where they installed the 11AC before moving to the 16AC. I've only seen the 11AC mentioned in the Optional Equipment catalog but why it was in there wasn't apparent. I do have the auxiliary battery charging circuit installed but not sure if it's related.

I was told by the dealer that the new ones would work but I'm concerned about the alternator turning faster with the smaller pulley. I'd also need a smaller belt to account for the smaller diameter pulley. I'm curious if anyone else has this alternator and what they have for a pulley/fan or what they've found.

Cheers

[jimrr]

sorry no answers here but your concerns are valid. I usually seek out a individual repair shop that's been in business a long time as they'll have what you need to get it right but it's not easy to find someone that doesn't advertise, nor needs to.

[roverp480]

What are the part numbers of the parts you have been supplied. My option parts book looks to have fan 601901 & the diagram shows your original fan ie with a disc attached , the pulley is 557412. The 16ACR has smaller simpler fan.
I have just looked at a Lucas spec for the 11AC and they can run up to 12500 rpm, so if with the smaller pulley it cannot reach that at max engine speed It should be OK

[tluchette69]

I have just looked at a Lucas spec for the 11AC and they can run up to 12500 rpm, so if with the smaller pulley it cannot reach that at max engine speed It should be OK

I didn't get part #s with the new parts but I'm curious now so I'll check with the seller. I believe I found the pulley so now just trying to track down the fan but if I'm unable to I'll run the new fan.

[tluchette69]

I asked about the part numbers but was told they don't have any and that they are purchased as a set. He believes my old pulley/fan were from a dynamo but I don't believe that to be the case as the diagram in the Optional Equipment Catalog clearly shows the fan that I have for the 11AC alternator. Also, I've ordered the pulley using the part # from the OE catalog and it's supposedly the same size as what I took off the old alternator.

I'll try the 80mm pulley and as long as the alternator produces enough volts and amps, it should be ok. I'm still waiting for the pulley to arrive, last check it was in NYC.