Belt question

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Baker7888

G-Body Guru
Dec 3, 2021
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Hey Dudes. I am doing an LT1 swap in my 78 malibu and using LT1 accessory drive. OE valve covers have a notch in the front to clear the alternator. Ive made my tall valve covers work by fabbing up a small bracket which raises the alternator a touch, effectively tensioning the belt. (See pic) the belt actually fits but i have the tensioner just about maxxed out. Is this an issue or should I start looking for a longer belt/smaller pulley somewhere ??
 

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78Delta88

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May 23, 2022
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Yes to longer belt or smaller idler. The number on the belt is in millimeters, from there just adjust accordingly.

Nice build BTW, very clean, good look.
 
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Baker7888

G-Body Guru
Dec 3, 2021
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115
43
Maine
Yes to longer belt or smaller idler. The number on the belt is in millimeters, from there just adjust accordingly.

Nice build BTW, very clean, good look.
Thanks on the build. I was hoping you wouldnt say yes to the belt/idler. How do I go about finding a longer belt? Auto parts stores aren’t very helpful these days. Actually I avoid them at all costs.

I heard a 93 LT1 used a smaller AC pulley which would probably be just about perfect (I am running an AC delete pulley) Looking though the various years on rockauto they all pull the same part number which is the one I have (larger one). I have limited clearance to the frame rail with this pulley so finding a smaller one is probably the better way to go
 

78Delta88

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May 23, 2022
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Thanks on the build. I was hoping you wouldnt say yes to the belt/idler. How do I go about finding a longer belt? Auto parts stores aren’t very helpful these days. Actually I avoid them at all costs.

I heard a 93 LT1 used a smaller AC pulley which would probably be just about perfect (I am running an AC delete pulley) Looking though the various years on rockauto they all pull the same part number which is the one I have (larger one)
I can work with my guys here. What is the belt number you are using now?
 

dmac35242

Not-quite-so-new-guy
Dec 23, 2021
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Birmingham, AL
The number on the belt is in millimeters, from there just adjust accordingly.
As Delta said, look for the numbers on the belt.
It doesn't have to be an LT1 specific belt as long as it's the same width and rib count. Most every serpentine belt out there will be like yours (in design, not length).
Do your RockAuto search after you determine the length you need.
I always buy belts local if I'm trying to figure out what fits.
I'll buy 4 or 5 that fall in my length range and return the ones that don't fit.
 
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Baker7888

G-Body Guru
Dec 3, 2021
665
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Maine

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78Delta88

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May 23, 2022
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I'll check with your numbers, will be later today. Below are just examples. On the 87 ElCamino we had to look through several books to find the idler, the original one was hitting the steering box. So it can be done...
 

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78Delta88

Royal Smart Person
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May 23, 2022
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As Delta said, look for the numbers on the belt.
It doesn't have to be an LT1 specific belt as long as it's the same width and rib count. Most every serpentine belt out there will be like yours (in design, not length).
Do your RockAuto search after you determine the length you need.
I always buy belts local if I'm trying to figure out what fits.
I'll buy 4 or 5 that fall in my length range and return the ones that don't fit.
Yep been there done that... Never got the t-shirt though.
 

78Delta88

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May 23, 2022
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1630mm is 64 11/64 (3/16) or close enough.

Add 8/16 = 1/2 inch = 64 11/16, or just try 65 inch belt.
 

Baker7888

G-Body Guru
Dec 3, 2021
665
115
43
Maine
So I was able to get a 90 mm pulley in town. I think it’s gonna be just about right as the alternator pulley was raised 3/4” (1-1/2” at the homemade mount) and it’s 1-1/2” diameter smaller than the oem pulley, or 3/4” radius.
 

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