V belt on a sbc

[93redzj]

Completely unrelated to 4wd but, I’ve got a 283 sbc sitting in my 62 Chevy, I need a V belt for the crank, water pump and alt. The one I currently have which is 3/8”x54 1/8” and it is waaaay to long. Does anyone by chance know which length belt I would need or is there a way to measure and see for myself? Thanks!

 

[Ron]

there are about 27 different bracket combos...no way to guess.

Take a shoe string or similar and run it around the pulleys and measure the length. that will give you the circumference.
Then go to gates website enter the length and width and v profile and it will spit out a part number that anyone can cross reference...

 

[Fabrik8]

Measuring the length with a shoe string on the smallest pulley OD (smallest diameter at the "flat" of the V-groove) will not directly give you the proper belt length, as you're measuring the inside circumference with the shoe string, almost. Modern V-belts are listed with either the outside circumference or the effective length, which takes into account the belt section/profile. For example, the part number of that belt in the photo says it is somewhere around 53.5 inches effective length, which is not the same as the 54.125 inch outside circumference on the label, because they are different measurements.

If you measure 34 inches with the shoe string for example, you're likely to actually need something like a 36 or 37 inch belt because of the difference in where the effective length (in the belt part number) is measured versus where you measured with the shoe string. The shoe string measurement is a starting measurement, not actually the length belt you need.

Really old school V-belt part numbers were listed with the inside circumference, but I'm pretty sure no one uses that numbering/measuring system anymore.

Just like anything else, you need to know what is actually being measured in order to get the correct part.

Just find an online calculator where you can start with inside circumference and belt section (you already have that from the package) and will output the belt length you will need to then find a part number.

 

[Chris_Keziah]

Just take the long one and measure how much shorter it needs to be. Just make sure you buy the same width belt as what you measure with.

 

[Ron]

Measuring the length with a shoe string on the smallest pulley OD (smallest diameter at the "flat" of the V-groove) will not directly give you the proper belt length, as you're measuring the inside circumference with the shoe string, almost. Modern V-belts are listed with either the outside circumference or the effective length, which takes into account the belt section/profile. For example, the part number of that belt in the photo says it is somewhere around 53.5 inches effective length, which is not the same as the 54.125 inch outside circumference on the label, because they are different measurements.

If you measure 34 inches with the shoe string for example, you're likely to actually need something like a 36 or 37 inch belt because of the difference in where the effective length (in the belt part number) is measured versus where you measured with the shoe string. The shoe string measurement is a starting measurement, not actually the length belt you need.

Really old school V-belt part numbers were listed with the inside circumference, but I'm pretty sure no one uses that numbering/measuring system anymore.

Just like anything else, you need to know what is actually being measured in order to get the correct part.

Just find an online calculator where you can start with inside circumference and belt section (you already have that from the package) and will output the belt length you will need to then find a part number.

Of course you are right about the shoe string not being perfect and you type faster than I do...
But itll get you close and those alternator brackets have almost 3 full inches of adjustment. If its an original PS he gets another couple inches there...so get close and take up slack with the adjustment.
Or just use rock auto

Id be more concerned with getting the v profile right or it will throw that belt (o shred it - depending on which way you mess up) than perfect length.

 

[Fabrik8]

For rough calc with the belt profile in the picture (10mm width, so 6mm depth), take the shoestring measurement which is the inside circum, add about 2 inches (45-50mm) to get the outside circum, and that should get in the ballpark for OC length to find a part number.

And to Ron's point, also make sure you remember to move your tension adjustments to a proper spot in their range before you do the measurement.

Id be more concerned with getting the v profile right or it will throw that belt (o shred it - depending on which way you mess up) than perfect length.

Absolutely. But also don't want to start with a belt that's 2 inches too short.

 

[93redzj]

For rough calc with the belt profile in the picture (10mm width, so 6mm depth), take the shoestring measurement which is the inside circum, add about 2 inches (45-50mm) to get the outside circum, and that should get in the ballpark for OC length to find a part number.

And to Ron's point, also make sure you remember to move your tension adjustments to a proper spot in their range before you do the measurement.




Absolutely. But also don't want to start with a belt that's 2 inches too short.

Glad you mentioned that I would have completely over looked that. Thanks for the help guys