Big Block Pulley Question

On some of the post '73 big blocks, I have seen a large idler pulley on the driver side of the motor that rolls along the (top) smooth side of the belts. I have only seen it on some motors and am wondering what the application is?

Normally the only thing on that side is the power steering pump. Smog pump maybe???

I’’m sorry- I meant to say passenger side.

Like this?

Yes! That's it!

It looks like it may be attached to the compressor bracket.

My 440 set up doesn't have it so I'm wondering which cars would have it?

is part of the compressor bracket and only have seen them on probably lates 74s


it is just to save the slapping belts issue due the distance between compressor and alternator when turning on AC. No adjustments there.

You can notice the front hose to compressor also changes with the in line reservoir more to the inner fender.

Wow! That's some bracket! I've never seen one like that. Thank you for the info!

Nacho is a wealth of information.

yes, well, thats the full compressor bracket setup ( rear and front ) shown like it was assemblied on compressor itself. This bracket with the pulley attached is of course a bit wider to gives the pulley provission area, but the rest of the bracket is actually the "same"

Can't tell REALLY when or what engines were used... maybe just 440s and maybe just mids/lates 74s ? Maybe 400s didn't get it because the distance is a bit shorter ( lower deck height gives less width too ) ? dunno, althought the pic showns a 400. Those brackets are not easy to find.

I have searched about this because I played with the pulley idea because I HATE the slapping belts when turn on my AC, but then I found they are not common and will need to make AGAIN the AC compressor line, so just forgot about that.

here a pic from the back side of the assembly

Not the best info source but I have had to learnt to save from buy wrong parts being imported to my place loosing money on the piece and shipping.

after 16 years on my car I think have learnt a bit thought

Yes Nacho is good people.