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Holley’s Sniper EFI For C2 and C3 Corvettes

Going EFI: Holley’s complete Sniper EFI fuel system enables you to go electronic fuel injection in a C2 or C3 Vette in a weekend

Jim Smart Oct 27, 2017
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With the technology we have today from Holley, it’s so easy to get into drop-in electronic fuel injection … and without breaking a sweat. You can quite literally pull your Quadra-Jet or Holley equipped C2 or C3 Corvette into the garage on a Friday and be back on the road Sunday with Holley’s Sniper EFI drop-in carburetor replacement system.

Holley’s new Sniper EFI master kit for C2 and C3 Corvettes is a specific fuel system economically priced so you can have all the benefits of EFI and still have money to finish or upgrade the rest of your Vette project, and we’re about to prove this with our 1968 small-block Corvette.

The Holley Sniper EFI master kit is the most complete EFI fuel system on the market because Holley provides you with everything to completely plumb your fuel system, including 20 feet of 3/8-inch EFI-rated hose, inline fuel pump, post and pre fuel filters, return bulkhead, and all of the necessary fittings and hardware. The Sniper EFI puts an end to cold start issues like we experience with carburetors. Hesitation, vapor lock, flooding … gone. Hop in, twist the key and start driving. It’s that simple.

We’re beginning our Holley Sniper EFI fuel system installation with a Holley fuel tank, which will accommodate virtually any electronic fuel-injection system. A 255-lph in-tank fuel pump, which we’ll use instead of the inline pump in the Sniper EFI kit, and a fuel level sender are included with the tank. Just add your existing filler neck and it’ll be ready to go. Although we’ve opted for Holley’s Sniper EFI system, you can use this tank for just about any EFI system, including factory GM electronic fuel injection. Vette

Sniper EFI Master Kit Features
Bolt-on carburetor replacement (designed to fit single and dual carburetor manifolds)
Throttle body mounted ECU (with no extra boxes to mount), self contained
Supports up to 650 hp (four-injector version) or 1,250 hp (eight-injector version)
Four-wire vehicle connection (battery +, battery -, switched ignition and rpm)
Includes complete fuel system consisting of 20 feet of 3/8-inch Vapor Guard fuel hose, fuel pump (PN 12-920), filters, necessary hardware and bulkhead fitting to return fuel to the tank
Integrated fuel pressure regulator
Integrated ignition timing control and coil driver
Color touch screen for setup and gauge views
Calibration Wizard (answer a few questions about your engine and it creates the base map, then starts tuning on its own). No laptop or tune shop required
Self-tuning ECU means you don’t have to be a computer/tuning wiz to have EFI
The included wideband oxygen sensor provides real time Fuel Map Learn

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This 1968 Corvette fuel tank, 18-gallon capacity, has been sitting around for more than three decades. We’re not only going to replace it; we’re going to go with one of Holley’s new EFI-style fuel tanks engineered to work with the Holley Sniper EFI system.

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What’s better than a stock fuel tank when you’re converting to electronic fuel injection? The Holley EFI fuel tank for C3 Corvettes (PN 19-148) and the slightly different tank for C2 Corvettes (PN 19-147) make it easy to get into EFI in a weekend. These tanks enable you to jump right into EFI without modifications because they accommodate EFI without cutting or welding. This is true bolt-on EFI performance in a box.

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These provisions adapted to the stock-style Corvette fuel tank are what make going to EFI easy. The stock tank has the fuel sending unit installed through the bottom of the tank. With Holley’s EFI tank, all fuel access is through the top like this without the risk of fuel spillage should you have to service the fuel system. The fuel filler opening is to the left, with the fuel sending unit and EFI pump to the right.

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This is the fully adjustable fuel sending unit, along with all of the appropriate gaskets.

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Here’s the lay of the gaskets Holley has provided for the fuel tank.

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Because Holley provides a fully adjustable fuel sending unit for the fuel gauge, the tank depth needs to be measured first in order to set up the sending unit float adjustment.

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Because Holley provides a fully adjustable fuel sending unit for the fuel gauge, the tank depth needs to be measured first in order to set up the sending unit float adjustment.

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The fuel sending unit works on the principle of resistance of current flow to ground. When there’s low resistance the float is at its highest point (full tank), the gauge reads full. By contrast, when the float is at the bottom of its travel, we have high resistance to ground and the gauge reads empty. Using an ohmmeter, you can check resistance to ground to determine proper float adjustment. In this image, the float is at its highest point with low resistance to ground and high current flow … a full tank.

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The Holley fuel sending unit slips in through the top as shown here. Check gasket security and snug this guy up.

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Now to the fuel pump, pickup, and return lines. Because this is a universal fuel pump, it has to be modified for the tank in which it is being installed. The pickup line is measured and cut to the tank’s depth minus the length of the fuel pump, with filter sock installed.

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The return line should be cut to where it doesn’t cause aeration at the pump pickup, which can cause pump cavitation and air in the fuel. If you have a returnless system, you won’t have to sweat this step.

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The electric fuel pump assembly is inserted into the top of the tank as shown.

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The pump is seated in the top of the tank and secured with the Holley-provided fasteners.

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We’re removing the fuel filler neck from the stock tank at this time to send it out for re-plating.

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Do you like our re-plated fuel filler neck? We have installed the neck with a new gasket and fasteners. The devil is in the details. We could have cleaned this neck up with abrasives and reinstalled. However, with plating, corrosion becomes less likely and the darned thing looks pretty good.

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Our Holley EFI tank is good to go with all of its connections in place. There are three fuel connections: fuel under pressure, fuel return, and vent.

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Most Corvette gas filler neck boots deteriorate over time. It is time to replace ours. The Corvette Central gas filler neck boot (PN 363075) is the correct thickness, angle, and material with the flat edge and rib per original equipment. It also has the drain hole for the overflow hose. If you examine our Corvette Central gas filler neck boot, it delivers a perfect fit.

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Most Corvette gas filler neck boots deteriorate over time. It is time to replace ours. The Corvette Central gas filler neck boot (PN 363075) is the correct thickness, angle, and material with the flat edge and rib per original equipment. It also has the drain hole for the overflow hose. If you examine our Corvette Central gas filler neck boot, it delivers a perfect fit.

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With our Holley/Corvette Central fuel tank installed, we’re ready to tackle the rest of the Holley fuel system. You can hard line your C2/C3 Corvette fuel system, which is suggested or go with flexible braided stainless steel hoses … both of which are available from the Earl’s Division at Holley. What you get from Holley is turnkey products all in one stop.

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Holley’s Sniper EFI throttle body carburetor replacement system comes in one convenient box for easy weekend installation. You cannot imagine how easy this system is to install and use. What’s more, you can hide it beneath your Corvette’s air cleaner and few will be the wiser that you have Holley fuel injection. At a glance, it looks like a carburetor for the purist who wants to look pure.

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Holley’s Sniper EFI from another angle. Top this guy with an air cleaner and it’s challenging to tell it isn’t a carburetor. It does so much more than a carburetor. Because it is electronic and offers precise fuel/air metering, your Chevrolet V-8 starts every time the same way. No goosing the throttle or having to mess with a choke adjustment. The Sniper EFI is self-learning. It learns your driving patterns and your engine’s idiosyncrasies. Once you have driven a few miles, the Sniper EFI adapts to your driving style and your engine.

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Here’s the Holley Sniper EFI system on our 350 Chevrolet at Westech Performance on the dyno. It is remarkable what this system can do and in short order. Tell it what you have and Holley’s Sniper EFI can handle the rest.

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Sources

Hot Rods By Dean
Phoenix, AZ 85027
623-581-1932
www.hotrodsbydean.com
Corvette Central
Sawyer, MI 49125
800-345-4122
www.corvettecentral.com
Holley
Bowling Green, KY 42101
866-388-5120
www.Holley.com

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