Need a little help please.

I just received a remanufactured compressor for my LT4. Its pulley is larger in diameter than the one on compressor I just removed. The serpentine belt barely fit over the old, slightly smaller pulley so it's not going to 'stretch' over the new larger one.

"Why not just reuse the smaller pulley then?" Ah ha! Glad you asked! Because my old compressor seized and mostly trashed the entire clutch assembly. I'm now forced to use the new one, but did the seller send the correct size pulley or did I have an incorrect (smaller) size that was installed on the (again, remanufactured) compressor that was in the car when I bought it three years ago? So many questions and no good source of answers. Sigh...

So, the smaller pulley measures almost exactly 4.5" diameter across the front pulley flange. The larger pulley is almost 1/2" larger at 4.9" across the flange. The flange is the easiest section to measure otherwise I would have taken the measurements of the pulley ribs directly. But this makes checking on a vehicle very easy. The photo below gives an idea of the differences between the two.



Original(?) on top, new one below. Which is the correct pulley for a 1996 LT4?

 

Crickets... 😕

 

Little hard to measure on the car, but mine appears to be 4.5" and it's original. Although I did have to replace the clutch on the pulley about 8 years ago.

 

Thank you for checking and sorry for my delayed reply. Getting a good and reliable answer to this question was more difficult than I expected.

I purchased a rebuilt compressor for my LT4 and what was shipped was a larger pulley as described in my first post. What was installed on my car when purchased, and clearly not factory-original, was a (badly) rebuilt compressor with the 4.5” pulley. Combining the fact that I had the wrong compressor (incorrect mounting ears, one shorter to clear something) and the supposed correct application as provided by the recent seller, I doubted anything placed in front of me that I couldn’t verify on my own. Could I have convinced the belt to go over the larger pulley? Maybe. But the 4.5” pulley and belt worked so well together that I was 93.175% convinced the 4.5” was the correct part. Eventually the seller got back to me and admitted that they sent the wrong pulley and said the 4.5” was what I needed. In the mean time I was under pressure to get my Vette back on the road as it’s my only functioning vehicle and that was going to happen one way or another. I was stuck having to make some decisions that could upset the compressor seller if I was obligated to return the big pulley, as I was going to have to ‘borrow’ the center bearing from it to install in my burned up pulley. I no longer was asking the seller permission to do the swap but told them it was something I had to do to get back on the road, and well after me doing what I said they agreed that it was okay. Better to ask for forgiveness than to ask permission. And of today I got notice that a new 4.5” pulley was being ‘prepared’ and would be shipped soon. I volunteered to send the big pulley back but was told not to bother. So that’s my story and I’m sticking to it.



Old A/C pulley bearing - destroyed from heat

Inside of overheated compressor pulley. There’s a thick layer of melted nylon coating the outer rim. The nylon was flung out of the overheated bearing

Much sandblasting later and the melted nylon is cleaned out, necessary otherwise the electromagnet that occupies this space will rub and overheat.

A little black paint added to slow rust formation while waiting on a replacement pulley

The clutch plate contact face of the pulley cleaned up using my little Sears Craftsman lathe and then belt sander to give it a ‘unidirectional’ friction surface. It works perfectly again.

All back together and functioning fine. How long will it last? No clue but hopefully the rebuild of the ‘new’ compressor will be done before this installed one blows up again.