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C3 Corvette Gauge Cluster - Flying On Instruments
Project C3 Triple-Ex Gets Proper Instrumentation For High-Speed Flight
Jan 6, 2011
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C3 Corvette Gauge Cluster - Flying On Instruments
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.
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.
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.
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 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 mechanical speedometer is precise to 200 mph and features a trip odometer as well.
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 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 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 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 removed after disconnecting the speedometer and tachometer cables, headlight switch, and associated wiring.
We'll start here, removing the factory tach and speedo to fabricate panels for our new Auto Meter replacements.
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 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 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 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 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 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 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 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 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 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 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 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 illuminated for nighttime driving.
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 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 is quite apparent.
We're happy to know that our Stingray now has proper instrumentation-and is one step closer to being ready for an awesome powerplant.
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