V belts for my Chevy C10 1974

Hi,

The belt for the generator broke the other day. The belt for the waterpump is worn out so I want to replace both of them. I am having difficulties finding the right replacement belts. It turns out the previous owner had replaced them with incorrect sizes - that's my guess anyway since they are metric, not inches. The one for the waterpump looks way too small too.

So, short question: What belts do I need to buy? It's a 350 engine. Pretty much stock. Links would be appreciated

Thank you.

br
Jesper

The easiest way is to use a piece of string or wire and wrap it over the pulleys to get a ball park measurement.

Here's a link to Rockauto for your truck.

https://www.rockauto.com/en/catalog...p,5.7l+350cid+v8,1030037,belt+drive,belt,8900

I looked it up on the Gates site, which is the only brand I use. But you didn't say if you had AC or not. I usually look up the part number, then buy from Ebay or Amazon.

For non AC, it looks like #7448 for the alternator, and #7360 for the power steering.

https://www.gates.com/us/en/ymm/sea...olet&model=C+&+K+Series+Pickup&engine=V-8+350

Yes, a piece of string does work. If you have the room you can also use a measuring tape and wrap it around the pulleys to get a number. I have to use different belts for my engine as well. I don't even give them the year of the truck or engine anymore because I would always get the wrong belt.. I give them the size and then I get the belt that fits. There may be something moved or isn't the factory pulley size anymore. Like WFO suggests, go by the size and forget about the part number. If you put a different power steering pump on the engine or change the pulley size you won't be able to go by the part number anymore anyway. Many times if you can see the number, the last two numbers is the length you are looking for, i.e. "48" is 48 inches.

i just picked up a 46 for my alternator based on length of the one that came off(3 inches off the original belts pn#) and a 32 for my ps pump. But thats not representative of the proper belts the engine originally had at all

Raider L said:

....<snip>....... Many times if you can see the number, the last two numbers is the length you are looking for, i.e. "48" is 48 inches.

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That "formula" won't work for Gates belts.. I have 3 Gates belts in my hand.. 7405 is 41 1/8" long.. 7335 is 34 1/8" long... 7305 is 31 1/4" long.. Last 2 numbers aren't even close to the length.. In years past, "8" as the first number denoted 13/32" wide and "7" as the first number meant 3/8" wide.. Not any more.. "7" as a first number could be either width.. One of these belts in my example is 3/8" wide and the other 2 are 13/32" wide..

RustyPile said:

That "formula" won't work for Gates belts.. I have 3 Gates belts in my hand.. 7405 is 41 1/8" long.. 7335 is 34 1/8" long... 7305 is 31 1/4" long.. Last 2 numbers aren't even close to the length.. In years past, "8" as the first number denoted 13/32" wide and "7" as the first number meant 3/8" wide.. Not any more.. "7" as a first number could be either width.. One of these belts in my example is 3/8" wide and the other 2 are 13/32" wide..

Click to expand...

It is not the last 2 numbers, the length is the last 3 numbers.
So your 7405 Gates belt is 40.5 inches long. That measurement is from the middle of the belt, not the outside diameter.

Yes the first number, 7 is the width, 3/8".

A Dayco belt also has the last 3 numbers for the length, but has 2 number width code. So your 7405 Gates belt is the same as a Dayco 15405

Turbo4whl said:

It is not the last 2 numbers, the length is the last 3 numbers.
So your 7405 Gates belt is 40.5 inches long. That measurement is from the middle of the belt, not the outside diameter.

Yes the first number, 7 is the width, 3/8".

A Dayco belt also has the last 3 numbers for the length, but has 2 number width code. So your 7405 Gates belt is the same as a Dayco 15405

Click to expand...

Those numbers I quoted, both length and width came from Gates sleeve for those 3 belts.. To respond to your comment... I didn't measure any of them, and don't intend to do so.. I'm just quoting what Gates prints on their belt sleeves....

Raider L said:

Yes, a piece of string does work. If you have the room you can also use a measuring tape and wrap it around the pulleys to get a number. I have to use different belts for my engine as well. I don't even give them the year of the truck or engine anymore because I would always get the wrong belt.. I give them the size and then I get the belt that fits. There may be something moved or isn't the factory pulley size anymore. Like WFO suggests, go by the size and forget about the part number. If you put a different power steering pump on the engine or change the pulley size you won't be able to go by the part number anymore anyway. Many times if you can see the number, the last two numbers is the length you are looking for, i.e. "48" is 48 inches.

Click to expand...

This can be quite a problem with older engines, in some cases, something has been changed with the belt setup, in others I think belt manufactures get it wrong.

@jerula , measure your belt length using the string method, or if you are on a friendly basis with an auto parts store, drive the truck there tell them you need a belt longer than the one you have go out and try it on. Might take a few guesses to get it right. I remember back in the day when V-belts were common we had one wall of the shop plastered with them, and sometimes we'd end up pulling a few down before getting the right one.

Regardless once you have found the correct sizes either write the part numbers down or hang on to the belt sleeves.

SirRobyn0 said:

This can be quite a problem with older engines, in some cases, something has been changed with the belt setup, in others I think belt manufactures get it wrong.

@RustyPile, measure your belt length using the string method, or if you are on a friendly basis with an auto parts store, drive the truck there tell them you need a belt longer than the one you have go out and try it on. Might take a few guesses to get it right. I remember back in the day when V-belts were common we had one wall of the shop plastered with them, and sometimes we'd end up pulling a few down before getting the right one.

Regardless once you have found the correct sizes either write the part numbers down or hang on to the belt sleeves.

Click to expand...

This reply is in response to your having quoted me, but it's directed to the OP of this thread. I'm a retired automobile mechanic having worked in the field for over 30 years, so you're preaching to the choir.. Over the years, I've fitted more belts than can be counted to more vehicles than can be counted under more situations than can be counted.. I don't have a problem fitting a belt to an "unlisted" combination of accessories.. As an example: I just finished installing power steering on a vehicle that didn't have it from the factory.. This vehicle has an engine in it that wasn't made until the vehicle was 14 years old.. Without measuring ANYTHING on the vehicle, I just estimated the distance between the pulleys to calculate the needed belt length. I walked out of the parts store with 2 belts.. Either one would have worked perfectly -- I installed the shorter one..

When I was a teen, I worked at PAW. We had the belts hung smallest to largest and a customer would walk in with a string and we had a tool that was a sliding ruler with two half circles and you put the string or unmarked belt on it, pulled it taut, and it told you what size belt you needed. Off of that you could cross reference to any brand you wanted. While it's been a few years, I would think any mom and pop would still have that tool.

With the OP being in Denmark, and the truck being 50 years old, it may get a bit complicated.

I would set all the accessories 50% in range of adjustment, string it and order the belts by length and start there.

If you are looking to upgrade and tired of v-belts:
For my sons truck, I bought a good working serpentine set-up off a '90 Burb for $60, cleaned it, powder coated, and bought new alt and ps pump, idlers, and belt. For roughly $200, I have nice reliable, easy to get parts, serpentine set-up that doesn't need adjustment. I could have used it just how I got it for $60 but I wanted it to have a "new or show" look.

RustyPile said:

This reply is in response to your having quoted me, but it's directed to the OP of this thread. I'm a retired automobile mechanic having worked in the field for over 30 years, so you're preaching to the choir.. Over the years, I've fitted more belts than can be counted to more vehicles than can be counted under more situations than can be counted.. I don't have a problem fitting a belt to an "unlisted" combination of accessories.. As an example: I just finished installing power steering on a vehicle that didn't have it from the factory.. This vehicle has an engine in it that wasn't made until the vehicle was 14 years old.. Without measuring ANYTHING on the vehicle, I just estimated the distance between the pulleys to calculate the needed belt length. I walked out of the parts store with 2 belts.. Either one would have worked perfectly -- I installed the shorter one..

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Sorry about that, you are absolutely right, as you can see from the time stamp on the message I wrote that quite late at night and simply mixed names up. I have gone back to my original post and changed who it is @ to the OP as it was intended to be directed at. Again I do apologize.

SirRobyn0 said:

Sorry about that, you are absolutely right, as you can see from the time stamp on the message I wrote that quite late at night and simply mixed names up. I have gone back to my original post and changed who it is @ to the OP as it was intended to be directed at. Again I do apologize.

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Hey man, no apology needed.. You didn't bother me in the least and if I came across otherwise, I'm the one needing to apologize.. What we have to remember as we help the OP with his belts is that Denmark uses the metric system to measure things.. So when we tell him to get a Gates (or Dayton) belt number XXXX, that may not be much help to him..

jerula said:

Hi,

The belt for the generator broke the other day. The belt for the water pump is worn out so I want to replace both of them. I am having difficulties finding the right replacement belts. It turns out the previous owner had replaced them with incorrect sizes - that's my guess anyway since they are metric, not inches. The one for the waterpump looks way too small too.

So, short question: What belts do I need to buy? It's a 350 engine. Pretty much stock. Links would be appreciated

Thank you.

br
Jesper

Click to expand...

Belts very seldom stretch very much before they break (gain length).. They wear mostly on the sides causing them to sit deeper in the pulley and just appear to be longer. Here is a measuring method that, in your case, might work better than a string.. You say the "generator" belt broke? do you have all the left over pieces? Lay them out in a straight line on a flat surface.. Measure the length in millimeters or inches.. Remove the water pump belt, cut it in one place and lay it out in a straight line and measure it's length. That will give you a starting length. When the belt is properly tensioned, you want the driven accessory setting at about the mid point of it's adjustment range or slightly less.. As for the belt width, This is just an educated guess on my part but I suspect your belts were originally 10 millimeters wide....

RustyPile said:

Hey man, no apology needed.. You didn't bother me in the least and if I came across otherwise, I'm the one needing to apologize.. What we have to remember as we help the OP with his belts is that Denmark uses the metric system to measure things.. So when we tell him to get a Gates (or Dayton) belt number XXXX, that may not be much help to him..

Click to expand...

You came across just fine, no worries from me, and that's a good point on the inches / metric thing, however to the OP. In your first post, you mentioned it had metric belts on it that were wrong, and if metric is what you put back on I don't think that would be so bad, as long as they are the correct length