quick question about accessory drive reduction ratios...

[ShredSled]

Looking to upgrade the accessory drive on an edelbrock 355 crate motor in a '67 swb stepper, and also add in power steering...
Has the alt. mounted on head on passenger side already... pretty sure it's a delco alt. (I've noticed a lot of companies listing different parts for Delco alt. and Denso alt... ?)

To say the least, reading through all of my options out there has my head spinning!


What reduction ratio do I want on all these pulleys?? Do I want 1:1 or 0% reduction?

Is 15% and 30% reduction considered the "under drive pulleys"?

I don't need that, it's not a race truck where I'm trying to squeeze out that last 5hp at the sacrifice of ps pump and alternator efficiency...

Or do I have all this backwards?
Will I need a smaller pulley on the alternator than on the others?

Is 1:1 ok for both PS pump and Alt.???

What are the stock, or close to stock reduction ratios for the accessory drive?




Please let me know, any related info is much appreciated here!
Thanks!





oh and also, on the ps pump, I want the block mount right, not the head mount?

[ShredSled]

help, anyone?

[Longhorn Man]

why not go with stock sized pullies? All underdriving does is free up a couple horses (which you said you don't need) and in return, increases the odds of overheating and undercharging.

[ShredSled]

yeah, I'm trying to figure out what the reduction ratio is of the stock pullies and go from there.

Looking at a KRC brand kit right now, along with their pump... So I wanted to determine if the stock OE pullies were 1:1 ratio, or had some sort of reduction...
One reason I ask is because I know for example the current alternator pulley is very tiny compared to the crank pulley... but, at least in photos, the KRC kit that is advertised as 1:1 has a GIANT pulley on the alt. (which in my mind would turn slower and I'm not sure why they would do that....?)