Guys, I'm having trouble finding the right belt size for the A/C compressor on my 460. It's a custom installation of a Vintage Air system in my '57 Custom. The current belt is slipping and is adjusted all the way to the end of the tensioning slots in the A/C compressor bracket. I have a Gates #7545 belt on it now that specs say is 55 1/8" outside circumference. I bought a Gates #7541 which is 54 3/4". Guess what? Too short!
These belts are .41" wide on top. I know I've seen wider belts in years past, but I can't figure out the size codes for belts in general. Do any of you have the magic decoder ring to find available belt width and length. If not, I guess I'll have to just go to Napa and look through their stock.
I found this online. There is a length and size in the belt number and Auto Zone explained it to me...I don't recall.. I just went through the same issue with an alternator belt. Hope this helps.
http://cloudfront.zorotools.com/img/zoro_tips/V-Belt_Selection_eZtip.pdf
I had a similar problem, not on a 460 but a car I changed from an generator to an alternator. The belts supplied by most auto parts stores today are smaller width as you have seen, which also makes the V smaller and they set to far down in the pulley. Goodyear makes belts that are actually .5 wide rather then .41 and have almost every length you can imagine. Sorry I can't find the link to that page, try Googling it. The only problem is they are only available through a limited number of suppliers.
7545=too long....7541= too short, sounds to me like a 7543 should work.
I used Vintage Air's universal bracket to fab up my 460 pump bracket. It looks like there's a lot of adjustment but it takes the exact belt to get it on and still have room to adjust it. The other thing I concluded is that there is a reason for dual belt pulleys. I ran mine with one belt. It chirped every time the clutched kicked in. I order the 'best' belt...it chirped. My solution was to run two belts. There are no OEM 460 pulleys that run AC dual belts. So I made them.
Thanks for all the replies. This is great information. I'll check all this out and let you know what I find.
Gasman, I'm envious! Yes, I'm trying to make a single belt work knowing dual belts would solve the problem.
I wanted to update this to let you know my A/C is working with no belt squealing! Finally found a NAPA #A54 belt that is wider and seems to grip better. Gave it run today in 90 degree weather and everything stayed cool!