How To

Gauging Your Options

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by Bruce Caldwell  More from Author

How to install custom gauges.

Street rod and custom car gauges range all the way from ultra simple to complex. Builders who lean more toward the custom side of the hobby tend to favor clean and simple, while the performance crowd likes lots of gauges to monitor every possible engine function.
Creativity plays a big role in how and where custom gauges are mounted. For hot rods, the two main options are using the existing gauge location/bezels or building a totally new dashboard. There are fiberglass components to ease custom dash building, but the top rod shops either lay up their own fiberglass or fabricate dashes out of sheet metal.


There are a myriad of different gauges, but they can be separated into a few general categories. In the most basic terms, the choices are analog or digital. Analog gauges currently dominate the hot rod scene. Digital gauges were the “hot” item when they first appeared in street rods. They went well with the whole high tech fad, but the tide seems to have turned back to more traditional cars.
For traditional style gauges, the main choices are OEM or hot rod/high performance. There are companies that market modern gauges with faces and dials that resemble the original six-volt gauges. Original style gauges work well in resto-rods. The most common/popular gauge style is the white or black face performance gauge. Some of these gauges (or styles) are referred to as Stewart-Warner or Moon Equipment style, after the popular gauge makers. These are the most traditional style, with simple graphics and basic bezels. The other popular style is the Auto Meter style competition gauges, though there are many other excellent gauge manufacturers.
As the hot rod/custom car hobby continues to grow, the availability of ready-made gauge panels has increased. There are many, many gauge panels that come with gauges already mounted. You simply remove the old factory panel, install the custom panel, and hook up the wires.


A gauge is simply an instrument that reads information sent to it from a remote source. There are electrical and mechanical senders. Most gauges are electrical, but some builders prefer mechanical oil and fuel pressure gauges. The mechanical gauges send oil or fuel to the gauge, while the electrical versions use a sensor that converts pressure to an electrical signal. Mechanical 
fuel pressure gauges must be externally mounted for safety.


Gauge hookups are pretty basic. In many cases, installation is the “plug and play” variety. If you have existing gauges and want to install new ones or different style units for the same functions, you can often unplug and remove the old gauge, mount the new gauge, and plug in (or attach) the wires.

Good gauges come with detailed instructions. They should also have the necessary adapters and reducers. Some gauges include universal senders, and others require that you order senders specific to your application. Gauges should also include the necessary mounting brackets and any special fasteners or spacers. Find out what is included with a potential gauge purchase, so you don’t have to do a lot of running around hunting for the small (but vital) hookup parts.

The actual wiring of gauges is quite simple. Gauges are marked on the backside as to which wires belong where, and the lights are usually wired separately. The hardest part of gauge hookup is finding the right fittings for the senders. Different engines and aftermarket intake manifolds have various sized tapped holes for senders. Auto parts stores have lots of reducers and adapters to fit any application if the fittings that came with the gauge aren’t quite right.


As simple as most custom gauge installations are, there are a few key things to keep in mind.

- Seal brass fitting with Teflon tape or Teflon paste for a secure fit.
Avoid stripped threads by not over-tightening fittings inserted into aluminum intake manifolds.
- Start the engine and check for leaks at sender locations after the gauges are installed.
- Do not remove an old sender while the engine is still warm. The sender probe will be hot.
- Never mount a mechanical fuel pressure gauge inside a car. Always mount them outside the passenger area.
- Disconnect the battery while installing gauges.
- Use as few reducers/adapters as possible if you don’t have an exact match. Each reducer or adapter is a possible leak source.
- Route wires and plastic tubing as far away from heat sources as possible.
- Keep wires and tubing away from any throttle linkage.
- Use wire ties or flexible wire looms to contain and route wires.
- When cutting mounting holes in fiberglass, cover the area with masking tape first. Plot the gauge hole locations with a marking pen, then cut through the tape with a hole saw.
- Measure multiple times for the center mark for the hole saw pilot hole.
- Keep the hole saw “teeth” parallel to the surface when drilling.
- Shrink-wrap tubing can be used to cover the bare wire where it joins a spade connector.


The more individualized approach is to custom fabricate a gauge panel. The key to building a custom panel is to lay it out on paper before cutting any metal or fiberglass. It helps to mock-up the steering wheel and seating position, so you can tell if the gauge placement is easy to see. If you have access to a copy machine that reduces and enlarges, you can copy potential gauge faces out of a catalog and position them on a gauge panel template.

Accurate measuring and even spacing are critical to a good-looking gauge panel. Measure several times and cut once. Most builders try to cut the holes right on the money and then do a little finessing if necessary. A snug fit is preferable to a sloppy fit, although the gauge bezels do extend past the holes.  

There are a wide variety of complete, ready-to-install, custom gauge panels for popular hot rods such as tri-five Chevy cars and trucks, thirties and forties Fords, and F-100 pickups. Gauge panels such as this one fit the factory gauge bezel.

The “before” part of a hot rod can be pretty ugly. It’s common for the original gauges to be either missing or damaged. Even intact gauges are usually 6-volt, so they need an adapter to be used with a modern 12-volt engine.

Here’s an “after” shot. The owner of this hot rod had the gauge faces color-matched to the dashboard. The two factory gauge holes were filled with a speedometer (left) and a multi-gauge cluster on the right. Rather than cut another hole in the dash, the tachometer was mounted to the steering column.

An advantage to installing gauges during a total buildup is that wiring tasks can be handled before the dashboard is installed. Many rod builders assemble the dashboard as a complete unit and then attach wires after the dash is installed.

By using spade connectors or male/female push-on connectors, the new gauges can easily be connected. All the wiring is in place behind the dashboard before the gauge cluster is installed.

This backside shot of a typical aftermarket gauge shows the spade style connectors. Each pole on this gauge is marked positive, negative, or ground. The metal item on the left is the mounting bracket.

In order to allow for different dashboard thicknesses, gauges have long mounting studs. Special knurled nuts (two are on the studs and an extra one is in the foreground) have a shoulder that fits inside the mounting bracket. The knurled feature allows the nuts to be adjusted up or down so the ends of the bracket are snug against the dash. Regular nuts secure the bracket to the studs.

Mechanical gauges such as this oil pressure gauge require brass compression fittings to secure the clear plastic tubing to the gauge and to the engine block. This gauge had been used, which accounts for the residual oil in the tubing.

The best gauge kits come with all the required adapters and fittings, but they can’t cover all possible combinations. Extra reducers can be used to fit an aftermarket intake manifold. These fittings are readily available at full-service auto parts stores. Plastic “T” fittings are used to tap into existing vacuum lines.

Senders are a key component of custom gauges. Senders are usually sold separately to fit specific installations. The larger sender is an electronic oil pressure sender, and the smaller sender is for a temperature gauge.

Hot rods aren’t known for their superior fuel economy, so having an accurate gas gauge is a must. Gas gauges use a float and a position sensor to electronically send the relative position of the float to the dash gauge. Shown here is a typical universal gas tank level sender kit.

A universal hot rod type fuel gauge sender has two nuts that allow the white position sensor to be moved up or down the slotted mounting bar. The float arm is connected to the short brass arm on the sensor.

Many street rod builders fabricate their own custom dashboards. Here is a custom dash in the very early stages of construction. Builder Travis Moore bent a piece of sheet metal to the desired shape and notched it for the steering column. He used masking tape and a marking pen to determine the gauge locations. Normally, the sheetmetal wouldn’t have surface rust, but this was a “back burner” project.

Travis transferred the taped shape on the dash to white poster board. He made a pattern to use as a guide for the gauge housing. Half-inch square metal tubing was bent, cut and welded to form the perimeter. Perforated steel was cut for the opening. The metal grille is backed by painted hardboard, but a variety of backings could be used.  

The gauge holes were spaced and centered before the holes were drilled. Travis used sections of steel tubing as bezels to position the gauges slightly above the perforated grille. The four smaller gauges on the left have uniform cut bezels, but the speedometer bezel was angle-cut to slant the gauge toward the driver (since it’s on the right side of the steering wheel). After all the welding is complete, the gauge panel and bezels can either be painted or chromed.

A classic hot rod gauge panel style is called engine turning. Engine turned aluminum panels have rows of uniform “swirls.” There are pre-made panels for many popular cars, or sheets of engine turned aluminum are available for custom installations.

There are nicely finished fiberglass dash panels that can be had with engine turned aluminum inserts. This simple dash panel is ideal for centrally mounted gauges as found on Model As and 1932 Fords. These universal dash panels allow the builder to customize the gauge locations.

Metal hole saws are the most common hole-cutting tools, but sheet metal punches can also be used. The advantage of a sheet metal punch is that it slowly and uniformly cuts a hole without distortion. The cutting die on the left is slowly drawn into the main part of the punch (right). The hole is started with a pilot hole the size of the threaded bolt.

The quick and easy way to mount a trio of small diameter gauges is with an under dash panel. There are simple, flat panels or more elaborate ones such as this thick, rubberized panel. This panel has an angled mounting surface to make the gauges easier to read. It can also be reversed to angle the gauges up from the transmission tunnel (that’s how the gauges are in this panel).

Vintage gauges like these sixties/seventies tachometers have become sought after swap meet items. Builders of old school rods are particularly fond of classic gauges. The Sun tach on the left is a steering column mount, and the other tach is set up for mounting on top of the dashboard.

Mechanical fuel pressure gauges should always be mounted outside, not in the dashboard. Should a fitting fail, you don’t want gas spilled inside the car. The cowl vent is a classic racecar mounting position.

Mounting an oversize tach on the windshield pillar is a nice racecar touch. This Auto Meter “Monster Tach” has a shift light, which implies lots of dragstrip action.

This gauge trio was mounted to the roll cage of an obviously race-themed car. The problem is that the exposed wires and cable ties don’t look very nice. A plastic wiring loom would look much cleaner.

There are a great number of dash panel/gauge installation variations, even for the same vehicle. The earlier engine turned gauge panel example was on a classic GM C-10 pickup. This example for the same style dash uses less elaborate brushed aluminum for the mounting panel.

This tri-five Chevy uses the factory speedometer in the center of the dash with modern fuel level and tachometer in the two flanking pods. A water temperature gauge was placed in its own pod on the left side of the steering column. The pod swivels to adjust the viewing angle. A matching pod on the right contains an oil pressure gauge.

This entire dashboard was custom built out of fiberglass. It was designed around this compact gauge cluster that’s surrounded by carbon fiber. The finished car is black with red leather, so the gauges were done to match.

At the other end of the difficulty spectrum from a custom built dashboard is the flat metal under dash gauge panel.

The central glove box on tri-five Chevys makes a reasonably accessible auxiliary gauge location.

Symmetry is an important consideration when laying out a custom gauge panel. This tach and speedometer evenly split the steering column and the smaller gauges are positioned off the big ones.


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