Pilots rely on accurate instrumentation...
Pilots rely on accurate instrumentation to fly high-performance aircraft; shouldn't you have the same advantage in your Corvette? This month we'll show you how we upgraded Project C3 Triple-Ex with Auto Meter gauges from Summit Racing Equipment.
While most automotive enthusiasts spend the majority of their driving time looking out the windshield, little thought is given to the next most popular place our eyes spend time while on the road. No, I'm not talking about the attractive person in the passenger seat, but rather the car's dash and instrumentation. As a driver, you likely don't even realize how often you steal looks at the instrument panel, quickly checking speed, rpm, or other engine functions before returning your attention to the road.
One of the reasons you may not notice how often you glance at your Corvette's gauges is the car's superbly engineered cockpit layout. Thanks to some careful planning, the instruments in a Corvette-even a '71 Stingray like Project C3 Triple-Ex-are placed so as to give the driver as much information as possible in the shortest time, with minimal distraction. At a time when many manufacturers were producing massively powered beasts of cars with a sweeping speedometer, a minuscule tach, and often just a light to tell the driver when oil pressure was lost, Chevrolet did an excellent job of providing full, easy-to-read instruments for its flagship performer.
But while proper gauge placement is critical, it's even more important that the instruments monitor engine and speed functions accurately. Unfortunately, the electric engine instruments installed in early Corvettes-along with the somewhat antiquated cable-driven tachometer-often work poorly or not at all, potentially leading to outcomes ranging from a pricey speeding ticket to an even pricier engine failure. While we're exaggerating a little here, knowing that your gauges work properly does instill a sense of confidence that your engine is operating within the correct parameters.
The factory speedometer and...
The factory speedometer and tachometer in early Corvettes are both cable driven, and while the speedos in these cars generally work well, the tachometers are notoriously inaccurate.
There are always choices when it comes to the instrumentation in your Corvette, and returning the dash to factory specifications is certainly a good option for stock restorations or even mildly modified cars. Companies like Corvette Central offer all the pieces required to restore your car's instrument panel to like-new condition, as well as dash pads and other pieces to make your car's dash look great. Because our project car is a blend of factory appearance and extensive performance modification, we chose to keep the dash's configuration generally as it left the factory, but replace the notoriously inaccurate stock gauges with more-precise Auto Meter Pro-Comp Ultra-Light instrumentation.
Installing aftermarket gauges in the factory dashboard of a C3 is no walk in the park. We had to remove most of the car's dash, perform a considerable amount of fabricating to get everything to fit where we wanted it, and even sacrificed our center air-conditioning ducts in order to make the IP more ergonomic. Even so, the center section was fairly easy to mock up and construct, and the engine gauges were easy to mount and connect, thanks in large part to the included wiring and hardware.
The speedometer and tachometer were simpler to install, only requiring the factory instruments to be removed and inserts fabricated to house the slightly smaller-diameter Auto Meter units. Of course we also chose to get rid of the groovy AM/FM/8-track in favor of a modern Alpine stereo unit, since we have a few more CDs lying around than we do 8-tracks. (Rumor has it that Editor Heath listens to Best of the Bee Gees in 8-track form, though he strenuously denies it.)
The factory used electric...
The factory used electric engine instruments to monitor vital engine functions; unfortunately these gauges often give poor information, or don't work at all. Repairing or replacing these gauges is certainly possible, but we decided aftermarket instruments best fit the theme of our modified shark.
Once finished, we found the new instrumentation to be both easy to read and accurate. Best of all, the Auto Meter Pro-Comp gauges modernize our Corvette's cockpit, better fitting the theme of this customized machine. As an interesting side note, we previously thought we had a cooling issue with the car, as the factory coolant-temp gauge would climb above 220 degrees (F) on a hot day. The new Auto Meter gauge verified that the engine was actually running a steady 180-190 degrees-right where it should be.
Best of all is that with proper instrumentation, we'll be able to accurately monitor the high-performance engine we're building to install in C3 Triple-Ex. We won't tell you what that engine will be just yet, but we can hint that we'll use these new Auto Meter gauges to keep an eye on the new powerplant's parameters while hunting LS7s. Stay tuned.
With hundreds of gauge styles...
With hundreds of gauge styles available, choosing the right ones for your car can be difficult. We simply picked up the Summit Racing Equipment catalog and compared different brands and styles until we found the right combo.
To help brighten up our Stingray's...
To help brighten up our Stingray's dark cockpit, we chose Auto Meter's Pro-Comp 2 5/8-in (diameter) Ultra-Lite line with brushed-aluminum faces. These gauges offer full-sweep accuracy and are easy to read, thanks to their black markings and bright orange pointers.
The Auto Meter 5-in Ultra-Lite...
The Auto Meter 5-in Ultra-Lite mechanical speedometer is precise to 200 mph and features a trip odometer as well.
The electronic tach will be...
The electronic tach will be far more accurate and responsive than the original cable-driven unit, and it even boasts a maximum-rpm recall feature. All of these instruments come with complete wiring and installation hardware.
Installing aftermarket instruments...
Installing aftermarket instruments in the dash of a C3 requires some serious disassembly. As much as we hated to, we began by removing our way-cool aftermarket 8-track stereo, which will be replaced by a more modern unit.
The C3 dash is composed of...
The C3 dash is composed of an upper pad, a center section, and right and left lower pads, all of which support each other. We needed to replace our lower passenger-side pad, so we began removing the dash on that side of the vehicle.
The factory instrument cluster...
The factory instrument cluster is held in with Phillips screws. Once removed from the dash, the wiring simply unplugs from the back of the panel. Don't worry about where the wires go: we won't use many of them with our new instruments.
The driver-side dash can be...
The driver-side dash can be removed after disconnecting the speedometer and tachometer cables, headlight switch, and associated wiring.
We'll start here, removing...
We'll start here, removing the factory tach and speedo to fabricate panels for our new Auto Meter replacements.
Using some polycarbonate panel,...
Using some polycarbonate panel, we traced the shape of the factory bezel onto the panel and used a jigsaw to cut it out.
Using cardboard from the package...
Using cardboard from the package the new instrument came in, we then centered the hole for the new tach and speedo and cut them out as well. The back side of the polycarbonate was then painted for a shiny, black face.
The new Auto Meter speedo...
The new Auto Meter speedo and tach can now be placed in the newly fabricated panels and attached using the supplied hardware. We also installed the gauge lights at this point and wired them together for easy connection later.
The driver-side dash can now...
The driver-side dash can now be reinstalled, the speedometer cable hooked up, and the wiring connected. Both the right and left lower dash pads must be in place in order to accurately measure the center panel.
Our passenger-side dash was...
Our passenger-side dash was pretty worn and flimsy, so rather than attempting a repair, we simply ordered a new lower dash pad and map pocket from Corvette Central. The new parts bolt right in place of the originals and look far better than our factory pieces.
The size of our new 2 5/8-in...
The size of our new 2 5/8-in engine instruments required us to fabricate a new panel. We started by installing the new radio bezel and measured from there.
We used the same polycarbonate...
We used the same polycarbonate sheet to fabricate our center instrument panel, measuring to space each gauge equidistantly from the others and the edges. Since our instruments are larger than the ones in the factory panel, we had to sacrifice our upper air-conditioning vents for proper spacing.
A jigsaw with a metal blade...
A jigsaw with a metal blade works best to cut the polycarbonate sheet. A compass, a metal ruler, and a Sharpie will be needed as well. Remember the adage, "Measure twice, cut once." After making the panels, pull off the paper and paint them; this creates a shiny black surface that can't be scratched from the front side.
We fabricated our panel to...
We fabricated our panel to use the factory attaching points, making installation a breeze. The wiring and associated sending units for the new gauges can now be fed through the new panel and secured in their new positions.
The Auto Meter fuel-pressure...
The Auto Meter fuel-pressure gauge is electric (you never want pressurized fuel in the cockpit), so a separate sending unit is placed in the fuel line. All of the wiring, sending units, lights, and hardware are included with these high-quality gauges.
Since we opted for oil-pressure...
Since we opted for oil-pressure and -temperature gauges, we had to utilize a brass T-fitting to split the line to the individual instruments. A sudden drop in oil pressure and/or a rapid increase in oil temperature can indicate an engine problem far quicker than rising coolant temps.
The bright faces of the Ultra-Lite...
The bright faces of the Ultra-Lite gauges are a nice contrast to the mostly black interior of our Stingray; they also offer useful functions such as a trip odometer and a maximum-rpm recall.
The instruments are also nicely...
The instruments are also nicely illuminated for nighttime driving.
The center instruments are...
The center instruments are placed to provide a clear view from the driver's position. We opted to make the two most often looked-at parameters-oil pressure and water temperature-our top two gauges.
The Pro Comp Ultra-Lite is...
The Pro Comp Ultra-Lite is just one of the instrument styles offered by Auto Meter. Check out Summit Racing Equipment's website or catalog to see which style best fits your car.
Side-by-side, the difference...
Side-by-side, the difference is quite apparent.
We're happy to know that our...
We're happy to know that our Stingray now has proper instrumentation-and is one step closer to being ready for an awesome powerplant.