Help me find my mystery belt

OK, this is starting to drive me nuts.

Way back in 2010 when I got my truck I decided to preemptively replace all the belts on the engine, since I didn't know how long they had been in there.  No problem, except for the belt driving the air pump - I couldn't find anyone who admitted to knowing anything about it.  No big deal, the belt looked to be in OK shape and it's just the air pump anyway, so I left it on there.

Fast forward to 2019, and the belt is starting to show some slight indications of possible wear:



Out of an abundance of caution, I've decided to replace it.  This time around, NAPA told me they knew just what I needed, and could order it and have it delivered in a few days (never mind that my local NAPA is physically attached to their Atlanta distribution warehouse).  It arrived yesterday, I tried to put it on today, and it was too long.  Even with the air pump swung out to the far end of the adjustment slot, the belt is still about an inch too long.

Measuring the belts, the new NAPA belt is 37.625" long, and the old one is 35.325" - so a belt around 36" even would be perfect.  Does anyone know of a place where one can order decent belts by physical dimension, and not by fitment?

See if you can find something, here:

https://www.rockauto.com/en/catalog/ford,1980,f-150,4.9l+300cid+l6,1121128,belt+drive,belt,8900

I've mentioned it before and I'll say it again.
Gates website has comprehensive listings by application, size, material, whatever..

And while you can't order direct from their website, if you can't cross a Gates# it isn't made..... anywhere.

Gates was my first stop, too.  And while I found the same belt there that NAPA sold me, I don't see any way to search by length or size.  

Gates calls out a #7320 for 1980 300-6 trucks with AC, and a #7381 for trucks without.

You can look those numbers up on their site and get the width and length.

I ordered two belts for my 300 from RockAuto last month. Same part number, two different manufacturers belts showed up. I have the double pulley setup. The belts are not exactly the same length even with the same part number. The belts I needed ran the alternator, water pump off the crank. I do not have smog pump or ac.

If you go to automotive V belts there is a tab "filter by"
Under that you can enter length, section, width, whatever....

7320 shows as a 32" notched belt 10mm wide and 36* angle.

7381 shows as a 38" smooth belt 6mm wide and 38* angle.

Gates 7417 is what I ordered. $4.31 per on RockAuto. Fan/Alt/Crank

Dayco 17460 for power steering

Matthew,

A 36" belt with the same angle and cross section as the 7381 will be part # 7359 in the Gates catalog.

ETA: #7363 is 36.5"

HTH

ArdWrknTrk wrote

Matthew,

A 36" belt with the same angle and cross section as the 7381 will be part # 7359 in the Gates catalog.

ETA: #7363 is 36.5"

HTH

Perfect, thank you!

Now, can you tell me how you figured that out?

EDIT: I see you told me that up above.  Again, thank you.

I guessed that 7381 had to be the belt you got from NAPA.
The other was much too short.

So I checked the cross section and noted H25.

From there it was easy to drill down with their filters

All of the auto parts stores I have worked at have had the belt measuring stick. Problem is, nobody knows how to use them, and you can't be sure they've used it correctly. I used to take the sticks to the front of the store and measure the belt in front of the customer, that way they can verify their own size and pick the belt they need. The size was usually in the part number, so finding belts wasn't too difficult if you knew the size and style you needed.