Alternator Pulley Size and Effect on Output.108A vs 120A, Different Rotor?

[Blown&Injected]

All the ALT's I have ordered have the wrong size pulley and they all say 108A on the front half of the case where the original one says 120A.

The parts guy says he can put the bigger pulley on for me. (Big deal I can do that too, I expect the part to be right as it comes). But won't this slow the ALT down thus causing a lower output?

Also, the 108A part makes me believe they are not using a Rotor from a true 120A ALT; maybe the faster (smaller pulley) makes up for the difference by spinning the Rotor faster.

What's the deal here?

Thanks

 

[salvageV6]

You want a CS144 alternator of 120 amperes output.

The 108's are wrong for all the reasons you listed.

Tell the parts guy to get the right one.

For free sure you could swap pulleys and use it, but no way if you are going to be paying for one.

 

[Blown&Injected]

How does one ID the CS144?
Thanks

 

[salvageV6]

Part Number 1101183

Made for a 3.8L Vin 7 LC2 motor 1987 year.

Rated Output 120 A should be stamped on the case.

There is also a 108 Ampere model CS144 made for the H bodied cars part number 1101250 you don't want those.

I got a brand new Pep Boys Pro Start made in the USA 120 ampere alternator for about $110 that worked well.

Did have to swap the pulley onto it however.

 

[Blown&Injected]

Thank You Sir.

 

[KendallF]

Originally posted by salvageV6
Part Number 1101183

Made for a 3.8L Vin 7 LC2 motor 1987 year.

Rated Output 120 A should be stamped on the case.

There is also a 108 Ampere model CS144 made for the H bodied cars part number 1101250 you don't want those.

I got a brand new Pep Boys Pro Start made in the USA 120 ampere alternator for about $110 that worked well.

Did have to swap the pulley onto it however.

I believe the only difference between the 108 A models and the 120 A models for our cars is the regulator. I've used several of the 108 A ones from the U-pullit and had a couple apart. The rotor, windings, diode pack, etc. appear identical. FWIW, the 108 A ones have worked fine for me...cheap bastard that I am!

 

[Blown&Injected]

The wires in the stator of the 108A unit I got were clearly smaller than the windings in my original ALT

 

[norbs]

what is the diameter of the smaller pulley?

 

[CraigT]

A stock pulley off of a 5.0 is smaller than our stock one, that is what I put on mine. And you can get them for next to nothing.