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How to Restore Your C3 Corvette: 1968-1982: Fuel and Spark Systems

by Walt Thurn

(Taken from How to Restore Your C3 Corvette: 1968-1982 by Walt Thurn) 

The electrical system ignites the fuel that powers your Corvette engine. The fuel is delivered to the carburetor via a fuel pump and the electrical system does the rest. Here is a brief overview of the fuel and spark systems.

Fuel Pump

Five different fuel pumps were installed into various C3 Corvettes. Each one was built for a specific engine application. It is very important to use the correct fuel pump for your engine, as the flow output for each one is different.

Here is a breakdown of the five different Corvette fuel pumps for the various engines that they fit:

1968–1969 427

1968–1969 327/350

1970–1972 LT1

1970–1974 454

1970–1981 350

1982 fuel tank electric pump

Corvettes were fitted with mechanical fuel pumps from 1968 to 1981. The pumps were located on the lower front passenger side of the engine. The pump brought fuel from the tank in the back of the car and sent it to the carburetor. A return line sent the unused fuel back to the tank. Stainless-steel lines were used to transport the fuel; rubber hoses are not recommended.

For 1982, Corvettes used an electric fuel pump that was located inside the fuel tank. This was the first year this system was installed into a Corvette.


Carburetor

Corvettes were fitted with a variety of carburetors. Three individual Holley 2-barrels were fitted to 400-hp engines in 1968, and to 400- and 435-hp 427-ci engines in 1969.


The 4-barrel Rochester Quadrajet was fitted to all other engine options in different variations until the end of production in 1981.


In 1982, General Motors introduced the ill-fated Cross-Fire fuel injection system. It used two throttle bodies to measure the fuel for the engine and produced 200 hp.


Spark Control

The factory installed a breaker-point ignition system on most 1968–1974 Corvettes to control spark. The exception to this rule was cars equipped with the K66 transistorized ignition option (called the High-Energy Ignition, or HEI). This option was only available for 1968 and 1969 high-performance Corvettes. A total of 11,159 1968 and 1969 Corvettes were delivered with this innovative spark system. It was a very successful application in L88-equipped Corvettes.


The HEI system was modified and became standard in all Corvettes produced from 1975 to 1981. It eliminated the need for points and produced a hotter spark for better emissions control.


Computer Command Control was introduced into Corvettes in 1981. The computer controls various functions inside the engine with a series of sensors that measure fuel, spark, temperature, and other functions of the engine. This system was also installed into 1982 Corvettes.


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