So how long have you been playing with old trucks? I started in my teens—more specifically, in the mid ’70s. Since that time we’ve witnessed change, from the very definition of “classic truck” to the manner in which we shop for their parts.

Perhaps you too are just old enough to have been spoiled by real parts professionals. It’s nice to walk into a store where counter help knows their business—and it’s a nice bonus when they know their customers’ names. Sadly, that’s no longer the norm. Today a simple V-belt purchase can be frustrating for the customer and sales person alike. This holds especially true when we need a belt that’s not an exact replacement part. There are, however, things we can do to make our odd-application V-belt purchases easier.

The procedure we’ll illustrate is nothing novel, but we have refined it to suit our own belt-sizing needs. By observing professional mechanics at Ed Martin Garage in Riverside, California, old dogs can learn new/old tricks. Established in 1934, Ed Martin Garage specializes in repair, restoration and modification of elderly cars and trucks, so V-belt purchases there aren’t always just by numbers. For that reason, used V-belts are kept on hand after replacement. The longer used belts can be cut to function as accurate samples, thus easing the match-up process considerably.

Since the adoption and further development of the Ed Martin Garage belt-sizing technique, we’ve used it with success at our home-based shop. In fact, we’re about to do it again. This time it’s on a 1955 Chevrolet second-series 1/2-ton pickup. The truck is an ongoing off-frame restoration with a little extra attitude. Its stock generator has made way for a Delco 1-wire alternator, which uses aftermarket bracketry. That makes our V-belt purchase perplexing at the parts store, but we’ll show how we deal with it. From here you’re all invited to follow along—all the way to the parts store counter if you like.

Our new and old alternator/generator pulleys differ in width. A swap goes easily with a Central Pneumatic impact wrench—the kind we’d find at Harbor Freight. This pulley will require restoration, but for the purpose of illustration we’ll continue through the belt-sizing steps as upcoming fresh paint cures.

Let’s begin the next step with a longer-than-necessary used V-belt. With the alternator snugged in the desired position, the belt must be pulled tight and held still for accurate marking. This can be awkward with only two hands, so chalk, or a crayon might be safer markers. For deadeye accuracy, however, we prefer something sharp.

After marking the spot, the final cut is made more easily on the bench. The cut sample belt is thin for our purposes, but it’s all we’d really need for the match-up. Even so, we’ll take it further by joining the ends. Since this belt is the cog-type, electrical shrink tube is the hot tip for the joint.

With the severed ends lined up in a short sleeve of shrink tube, the graft is quickly tightened—in this instance using an old Milwaukee heat gun.

By locating the joint section of our sample belt in the groovy part of the water pump pulley we’ve found traction. Now we can actually tighten our grafted sample belt in place for a test-fit.

Now at risk of expounding the obvious, let’s back up just a bit. If we’d needed a longer sample—longer than any of our used belts—we’d use two used belts to make one.

For measuring such grafted samples, there’s a wonderful old tool called the Gates Belt Length Finder. Oddly, they’re not used in every parts store today. However, since new V-belt part numbers usually divulge dimensions, a cut sample can be measured and matched this way as well. After the test-fit, cut it back apart.

So here’s a look at the finished job with the proper-width pulley now installed on the alternator. Granted, there are other methods for odd-application belt-sizing, but since taking our lesson from Ed Martin Garage, we no longer struggle with string. So gather some old belts for next time. They can still be useful as tools.