Belt sizes

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

MisterB

Full Access Member
Joined
Sep 9, 2019
Posts
676
Reaction score
845
Location
Northwest
First Name
AJ
Truck Year
1980
Truck Model
GMC K2500 4X4
Engine Size
350
I've got a 350 with power steering and no A/C. I would like to replace both the fanbelt/alternator and the fanbelt/power steering. NAPA shows both belts are the same exact part number. Does that sound right?

Sent from my SM-N975U1 using Tapatalk
 

Octane

Full Access Member
Joined
Dec 31, 2019
Posts
1,990
Reaction score
3,549
Location
Atlanta
First Name
Eddie
Truck Year
1977
Truck Model
K10
Engine Size
350
A Gates 7360 power steering to fan. 1977 k10 350 is what is on mine.And a 7448 for fan to alternator.Mine also is a non a/c
 

MisterB

Full Access Member
Joined
Sep 9, 2019
Posts
676
Reaction score
845
Location
Northwest
First Name
AJ
Truck Year
1980
Truck Model
GMC K2500 4X4
Engine Size
350
A Gates 7360 power steering to fan. 1977 k10 350 is what is on mine.And a 7448 for fan to alternator.Mine also is a non a/c
Interesting. I wonder if it changed in 1980, or if it makes a difference mine is a 3/4 ton K25?

Sent from my SM-N975U1 using Tapatalk
 

Octane

Full Access Member
Joined
Dec 31, 2019
Posts
1,990
Reaction score
3,549
Location
Atlanta
First Name
Eddie
Truck Year
1977
Truck Model
K10
Engine Size
350
Interesting. I wonder if it changed in 1980, or if it makes a difference mine is a 3/4 ton K25?

Sent from my SM-N975U1 using Tapatalk
I dont know about the other models.I replaced my belts in 2018 because they had been on the truck since 2003 and I was afraid they would rot off going down the road. Lol
 

Chevyguy

Full Access Member
Joined
Sep 10, 2012
Posts
185
Reaction score
60
Location
Eugene,OR
First Name
Clayton
Truck Year
1987
Truck Model
V20
Engine Size
5.7 Litre
Interesting. I wonder if it changed in 1980, or if it makes a difference mine is a 3/4 ton K25?

Sent from my SM-N975U1 using Tapatalk
It depends on how much adjustment room you have. As long as a belt fit's the Pulley's correctly a shorter, or longer belt will fit as long as the proper tension can be put on it. This Summer the serpentine setup I pulled off a 92 GMC Sierra 5.7 is going on my 87 V-20.

Clayton

Sent from my SM-A705U using Tapatalk
 

80BrownK10

Full Access Member
Joined
Oct 22, 2019
Posts
1,878
Reaction score
1,240
Location
Greenwood, SC
First Name
Nate
Truck Year
1980
Truck Model
K10
Engine Size
350
Interesting. I wonder if it changed in 1980, or if it makes a difference mine is a 3/4 ton K25?

Sent from my SM-N975U1 using Tapatalk
I have an 80 k10 with 350. I do not recall two identical belts on it. I do have AC but not running the belt as it doesn't work anyway.

I do remember getting a wrong belt for the PS I believe first. There several belts that could be on it if I remember right. Tomorrow I will get the numbers off mine if you want
 

75gmck25

Full Access Member
Joined
Oct 13, 2016
Posts
2,018
Reaction score
1,811
Location
Northern Virginia
First Name
Bruce
Truck Year
1975
Truck Model
K25 Camper Special TH350 NP203
Engine Size
5.7
For my ‘75 K25 the belts are definitely not identical in length.

There are two choices for my PS belt. The shorter one only goes around the crankshaft and PS pulleys. The longer one (with HD cooling) also goes around the water pump pulley. With the longer belt you can have a loose or broken alternator belt, and the PS belt will still keep the water pump turning.

Bruce
 

MisterB

Full Access Member
Joined
Sep 9, 2019
Posts
676
Reaction score
845
Location
Northwest
First Name
AJ
Truck Year
1980
Truck Model
GMC K2500 4X4
Engine Size
350
Thanks guys. I took a pic of my belts, and one of them still had the NAPA part number on it, which matched the part number their web site still shows is correct. The other belt is more worn, and I can't see a part number on it.

Went ahead and stopped by NAPA, and they confirmed that both belts should be the same size, so I paid for the online store pickup order. I haven't replaced them yet, but I'll let everyone know how that goes. I'm hoping there is enough adjustment to make the other belt fit, but we shall see. I wouldn't be too surprised if I have to take the old belt in to have them manually find one that is the same size

Sent from my SM-N975U1 using Tapatalk
You must be registered for see images attach

You must be registered for see images attach
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
5,882
Reaction score
9,623
Location
Washington
First Name
Todd
Truck Year
1986
Truck Model
K20
Engine Size
454
Take belt off measure the length, buy the same length or one size longer or shorter if it helps with the adjustment range.
You can do all this from home and know which one you need to buy before even going to the store.
 

80BrownK10

Full Access Member
Joined
Oct 22, 2019
Posts
1,878
Reaction score
1,240
Location
Greenwood, SC
First Name
Nate
Truck Year
1980
Truck Model
K10
Engine Size
350
How many blades is your fan??

Thanks guys. I took a pic of my belts, and one of them still had the NAPA part number on it, which matched the part number their web site still shows is correct. The other belt is more worn, and I can't see a part number on it.

Went ahead and stopped by NAPA, and they confirmed that both belts should be the same size, so I paid for the online store pickup order. I haven't replaced them yet, but I'll let everyone know how that goes. I'm hoping there is enough adjustment to make the other belt fit, but we shall see. I wouldn't be too surprised if I have to take the old belt in to have them manually find one that is the same size

Sent from my SM-N975U1 using Tapatalk
You must be registered for see images attach

You must be registered for see images attach
 

SquareRoot

Full Access Member
Joined
Mar 18, 2017
Posts
3,659
Reaction score
6,600
Location
Arizona
First Name
Mike
Truck Year
85
Truck Model
K20
Engine Size
350
Go to the wrecking yard and pull the entire serpintine system off a Vortec sb. It's the best "less than a $100" upgrade you can do. Dump the ancient Vbelts.
 

Chevyguy

Full Access Member
Joined
Sep 10, 2012
Posts
185
Reaction score
60
Location
Eugene,OR
First Name
Clayton
Truck Year
1987
Truck Model
V20
Engine Size
5.7 Litre
Go to the wrecking yard and pull the entire serpintine system off a Vortec sb. It's the best "less than a $100" upgrade you can do. Dump the ancient Vbelts.
I got mine off a 92 GMC 2wd 1/2 ton. The fan won't fit my 87's shroud so I need to get a 19 inch reverse rotation fan. I'm going to upgrade to a 115 amp alternator. My serp setup cost $125, hope to install this summer.

Sent from my SM-A705U using Tapatalk
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,121
Reaction score
6,038
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
Thanks guys. I took a pic of my belts, and one of them still had the NAPA part number on it, which matched the part number their web site still shows is correct. The other belt is more worn, and I can't see a part number on it.

Went ahead and stopped by NAPA, and they confirmed that both belts should be the same size, so I paid for the online store pickup order. I haven't replaced them yet, but I'll let everyone know how that goes. I'm hoping there is enough adjustment to make the other belt fit, but we shall see. I wouldn't be too surprised if I have to take the old belt in to have them manually find one that is the same size

Sent from my SM-N975U1 using Tapatalk
You must be registered for see images attach

You must be registered for see images attach

Is your setup a belt that goes around crank, waterpump, and alternator, with another belt that goes around the crank, waterpump, and power steering?
 

Forum statistics

Threads
41,856
Posts
903,586
Members
33,368
Latest member
TheDuke
Top