GM / Delco 12SI alternator mounting & power steering

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Jan 17, 2005
Vancouver, Washington
I haven't seen the info for this, and I have searched so please don't assume I haven't.

I'm mounting a 12SI alternator on my '77 2F. I'm planning on using the stock bracket modified a bit, along with an aftermarket ~2" pulley. From what I've been able to measure, it would be quite a bit easier if I mount the alternator to run on the pulley set closest to the block. This will then require that I mount my future power steering pump so that it uses the the outer pulley groove (closest to the radiator).

I haven't seen too much info on the mounting of the power steering pump, but it looks like mounting it so that it runs on the outer pullery shouldn't be a problem. But..... before I start down this road I thought that I'd ask if I'm doing something not so smart.

Let me have it...........

:confused: Anyone with feedback?

I did a saginaw with the pump using the outer pully. no probs
You can run the pump and alternator off the same inside belt if you want, but the down side is this will leave you with only 1 belt driving the water pump.

Skip the new pulley. You don't really need a smaller diameter. Just use the Toyota wide belt pulley.
Don't have a 2F but my 350 has the alt on the fwd pulley and the PS pump on the aft pulley.

I don't see any problems with doing it.

Are you concerned with the sizes of the different grooves? Are they the same size? That would be my only question, not sure how fast each item is supposed to spin so it might be a factor.

Have at it and let us know what you find.

My new pulley is for a 5/8 inch belt, so the size is correct. From what I can measure, it looks like I'll be spinning the alternator at 3 times the crank rpm. My friend with a small block Ford looked at his pulleys and he's running pretty much the same ratio on the alternator drive.

I really wanted to run the smaller pulley so that the alternator will produce a decent amount of current at idle or there abouts. I'll have to put an ammeter on and see how my system works once I'm done.


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