Correct Alternator Belt for big block Chevy with A/C?

[71CHEVYSHORTBED402]

Working on a 71 402 with A/C. For what worth I'm installing a 61amp 10SI.


I pulled a 56" belt, but the A/C wasn't running and the belt may have been shorter than original. Perhaps it doesn't matter much, because the alternator bracket can take either one, though the belts aren't the same width either.

I'm leaning to whatever is right but from here I can't tell what that is, what do you think?

Hard to read the images, the top image for C20 doesn't distinguish between A/C & 62 AMP generator. No mention of C10 BBC, they skip to C20. The second image does provide for C10 & distinguishes for A/C & 62 AMP generator, but only for a 396. I have a 402, but guessing they're the same.

Alternator Belt: 3917208 - 3/8”, 56”, though maybe a 9433770, 7/16, 59” for A/C & 62 AMP Alternator.

Original images:
http://www.gmpartswiki.com/getbigpage?pageid=21309

http://www.gmpartswiki.com/getbigpage?pageid=21306

[body bolt]

To me it looks like 7208 for the alternator and 3772 for the compressor.

[CG]

I don’t know if this is any help at all. Here is a picture of my alternator belt on my 71 with 402 with air. I looked it up online and it is a DAYCO OEM equivalent 45.07 in outside circumference

[71CHEVYSHORTBED402]

Originally Posted by body bolt

To me it looks like 7208 for the alternator and 3772 for the compressor.

7208 is what I initially thought until I read the second page in the OP, though it's for 396. I think I agree to stick with 7208, it's the NAPA I pulled and I only see one indentation indicator on the alternator bracket anyway. I'll have to ask the old man at NAPA why the difference in width between that and the 3770 on the 396. Perhaps it's the pulleys.

Originally Posted by CG

I don’t know if this is any help at all. Here is a picture of my alternator belt on my 71 with 402 with air. I looked it up online and it is a DAYCO OEM equivalent 45.07 in outside circumference

Wholly smokes 45", different pulley? If anything the indent on my upper bracket is closer to the inside than where yours is bolted.

[CG]

I just did a google search to get that number, its very possible I'm wrong on the length haha. But the truck is an 80K original, and as far as I can tell its all stock except for some wiring mish mash and an extra overflow or fluid bottle.

[71CHEVYSHORTBED402]

Originally Posted by CG

I just did a google search to get that number, its very possible I'm wrong on the length haha. But the truck is an 80K original, and as far as I can tell its all stock except for some wiring mish mash and an extra overflow or fluid bottle.

You're not wrong on the length, sure that's not a picture of your Corvair or? Which pulley is bypassed Did you stretch it with a Sherman Tank All serious I'm no expert, but 12" plus strikes me a big difference, especially when you have the same bracket I do, you must have a 71 as well.