Finding Serpentine Belt Lengths

[Doppleganger]

I have an original AC Delco serpentine belt kit for my motor but with all the customizing, etc. its too short. I ran a cloth measuring tape on the pulleys and found it to be almost 4" longer than the 'original' (this with the tensioner fully retracted).

Question I have is: do you measure the new belt with the tensioner fully relaxed or do you add a couple inches +/- for when its under tension?

THX

 

[Radiohead]

I would measure with the tensioner in the mid range and go with the closest sized belt available. That way you have some range to work with that would hopefully keep adequate tension.

 

[85K304SPD]

I just went through this. Trial and error. A few MMs makes a big difference. Take the belt that you have, and the measurement you make with the measuring tape, and try to figure out which one you need, see what the parts store has in stock and get the closest one and go try it out. If its the wrong size, take it back right away and get a different one. Make a couple of marks on your tensioner at the "tight & loose" positions and shoot for half-way or a little less because it will stretch a little. Good luck. (I have a couple of "too long" belts that I tried to run, but they squealed, that I didnt take back RIGHT AWAY.)

 

[squaredeal91]

I have an 87 cameo engine with a/c pump removed. No special idler pulley kit Simply measured estimated length. Possibly canabalized old belt and went to Napa and it fit great the first time. I think I measured it at mid range as well.

 

[Ricko1966]

I have an original AC Delco serpentine belt kit for my motor but with all the customizing, etc. its too short. I ran a cloth measuring tape on the pulleys and found it to be almost 4" longer than the 'original' (this with the tensioner fully retracted).

Question I have is: do you measure the new belt with the tensioner fully relaxed or do you add a couple inches +/- for when its under tension?

THX

Cut the belt,overlap the ends 2 inches,clamp it with vice grips,now try to install the belt. Too short? Too long? Move your overlaps.Now you have an example belt. You could even use a piece of 1 by or sheet metal and sheet metal screws to hold your overlaps.

 

[squaredeal91]

Cut the belt,overlap the ends 2 inches,clamp it with vice grips,now try to install the belt. Too short? Too long? Move your overlaps.Now you have an example belt. You could even use a piece of 1 by or sheet metal and sheet metal screws to hold your overlaps.

I think that's exactly what I did lol. Been a long time

 

[Doppleganger]

So I find what I believe is the perfect size. Was exactly the length I measured and fit well. Only oddity it was a cheap house brand from OReillys. I order an AC Dilbert gold belt in the same size only to find out they run differently. Fits well but has too much give IMO. Barely pushing I can get it to touch. Not crazy about the clearance at the alt bolt head either - might swap in a button head there. Napa clerk says the books on all these belts show "ranges" they fit. WTF? So I order another AC Dilbert 1/2" shorter. We'll see how belt #4 fits. UFB.

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[CalSgt]

So I find what I believe is the perfect size. Was exactly the length I measured and fit well. Only oddity it was a cheap house brand from OReillys. I order an AC Dilbert gold belt in the same size only to find out they run differently. Fits well but has too much give IMO. Barely pushing I can get it to touch. Not crazy about the clearance at the alt bolt head either - might swap in a button head there. Napa clerk says the books on all these belts show "ranges" they fit. WTF? So I order another AC Dilbert 1/2" shorter. We'll see how belt #4 fits. UFB.

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I went through about 6 before I figured out exactly what belt to get for mine and it’s all factory stuff. Good luck Sir.

 

[Doppleganger]

Belt #4 was perfect. Felt like I was playing Name That Tune.....I can guess that belt length in 5 tries.

I can get it in 4.

Name that length.