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Bringing a Quadrajet four-barrel back to life

Wake Up Call!: What it takes to bring back to life a pair of Q-jets and the Corvettes stored underneath them for decades

Jim Smart Sep 5, 2017
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Aren’t barn and garage finds wonderful? A diamond in the rough sitting there lost to another time. The good news is you found them and you have an opportunity to have a lifetime’s experience. Two Corvettes asleep all these years. In truth, there’re a lot of them to be found out there. They were hot-rodded, blown up, smashed in accidents and many times just parked as family heirlooms put away for another day and then forgotten.

The downside of a garage find is the deterioration caused by the vehicle sitting around for a long time. Much like we humans … use it or lose it applies to vehicles, too! As such, cars like to be driven. Most garage finds are in pretty bad shape and haven’t been protected from the elements. We know what these elements are: freezing, thawing, humidity, dust and dirt on the wind and ozone and other the elements in the air that make things age. It all finds its way to a stored automobile, even in an enclosed garage. These gems have been sitting for so long, sometimes for decades, to where it’s challenging to get them running again. Some are beyond salvageable and must be torn apart because, unless they have been stored in a dry environment out of the weather, chances are good they are rusted and seized up internally. Game over.

As future articles will point out, the staff here at Vette came across two Corvettes (a 1968 and a 1971) that were stored for decades (the ’68 for 37 years and the ’71 for 25) that had been napping in the dry desert for a long time. We’re in the process of returning these American classics to service as driveable automobiles. How you return a vehicle to service when it has been sitting for a long time depends on how it was stored in the first place? If it was parked with a half tank of gasoline the verdict is grim because you’re going to have to get rid of the bad gas and freshen up the fuel system to even get the thing to fire.

There are also engine, driveline and brake system issues that must be handled for safe operation. From the fuel tank to the carburetor you have a lot of work to do. The engine oil and filter must be changed, same with the transmission fluid. Old coolant, if it’s even still there, will have to be changed out with fresh 50/50 coolant. Rotted hoses, all of them, will have to be replaced. Differential lube should also be changed out. It’s a good idea to remove the spark plugs, perform a tune-up, pour a teaspoon of 30-weight oil into each cylinder and slowly hand crank the engine to make sure everything is loosened up. Ideally, you would also pull the valve covers and pour engine oil over the rocker arms and valvesprings to ensure a slippery start-up with minimal metal-to-metal contact. (Another way to get the oil flowing is to grab your handy ARP oil pump primer tool, pull the distributor and spin the oil pump until oil works its way up top.) It doesn’t hurt to perform a compression check, either, just to make sure you don’t have any valves stuck open from the long sit.

We’re beginning this wake-up process by rebuilding a pair of Rochester Quadrajet carburetors from the two Corvettes. We’re at Hot Rods by Dean in Phoenix to ensure this process is performed properly. Each Q-jet will have to be disassembled and boiled out, with their passages and boltholes chased before a complete reassembly and tuning.

Engines don’t run well—if at all—with gunked-up carburetors because automotive fuels, especially today’s fuels laced with destructive ethanol, do incredible damage to carburetors when they sit for a long time. Ethanol damages the die-cast causing excessive corrosion and permanent damage. This is why a complete carburetor teardown and rebuild with new soft and hard parts is so important.

To help us out we visited our local Edelbrock dealer and picked up a pair of Q-jet rebuild kits. From there it was a matter of remove, disassemble, clean, rebuild, install and go for it. Amazingly, both cars responded.

We used an old power steering reservoir to hold fresh gas, and—resembling a military triage center—the gasoline was gravity fed to the carbs on both engines. From here we did change out the engine oil and filter with 6 quarts of AMSOIL products, installed a fresh Optima battery, aired up the tires, and went through some basic electrical checks. We also spun both engines over by hand at first to make sure they weren’t frozen (and they weren’t) and proceeded.

The ’71 was the first to have its carb rebuilt, and amazingly on the second crank it fired, belched out some foreign matter and blue smoke from the exhaust but shortly it settled down. Bob Kleiner deftly fine-tuned the carb and soon it began to run smoother and quieter … job well done.

Then it was on to the ’68. We were feeling pretty good about our mechanical prowess … well, truth be told, we stood around while Kleiner proceeded to prep the ’68 and then fire it up. Again, a couple of cranks and it, too, came to life. Truly amazing. Well, there will be more on this saga of the non-identical Corvette twins coming back to life but for now they’re (and us) off to a good start.

Corvette Edelbrock Quadrajet Carb Rebuild 002 2/28

1. Dean Livermore of Hot Rods by Dean (left) and Bob Kleiner are going to tackle a couple of decades-stored C3 Corvettes in an effort to get them roadworthy once again, beginning with a couple of dusty-crusty Rochester Quadrajet carburetors.

Corvette Edelbrock Quadrajet Carb Rebuild 003 3/28

2. This is your basic period Quadrajet at the beginning of tougher federal emissions standards enacted in 1968 with a controlled-vent fuel bowl before GM went to evaporative emissions control. For an atomizer that has been sitting a while this Quadrajet looks pretty good and should be able to be returned to service with ease. The Quadrajet was conceived as an emissions carburetor, not for performance. If you know how to build and tune a Quadrajet, this is a carburetor that will perform very well.

Corvette Edelbrock Quadrajet Carb Rebuild 004 4/28
Corvette Edelbrock Quadrajet Carb Rebuild 005 5/28

3. Disassembly begins with the removal of the fuel filter at the inlet. The fuel filter’s condition will be a clue as to what to expect inside. Expect to see scale corrosion from ethanol contamination if the car was parked in recent years. Bad fuel kills fuel systems with corrosion and gum.

Corvette Edelbrock Quadrajet Carb Rebuild 006 6/28

4. The choke and pull-off assembly are removed next using a cross-slot screwdriver.

Corvette Edelbrock Quadrajet Carb Rebuild 007 7/28

5. A handful of cross-slot, fine-thread screws are removed and the air horn comes off. Be mindful of the little tiny pieces that can get lost. Be sure to account for every part.

Corvette Edelbrock Quadrajet Carb Rebuild 008 8/28

6. The idle mixture screws are removed next. Mark them and return them to the same location during reassembly.

Corvette Edelbrock Quadrajet Carb Rebuild 009 9/28

7. The accelerator pump check ball and fitting are removed next. Place these tiny parts in a magnetic tray for safe keeping. Obviously, the brass isn’t going to be magnetic but you get the idea. There are no unimportant parts.

Corvette Edelbrock Quadrajet Carb Rebuild 010 10/28

8. The float needle valve and seat are next, once the float has been removed. We are going to replace the float with a new one from the Edelbrock kit, which has everything for your Quadrajet.

Corvette Edelbrock Quadrajet Carb Rebuild 011 11/28

9. The main metering jets are removed next with a cross-slot screwdriver. If you can’t get them loose, soak them with a penetrating lubricant, which is available from AMSOIL or through Summit Racing Equipment.

Corvette Edelbrock Quadrajet Carb Rebuild 012 12/28

10. Catch all the vital carburetor parts in a magnetic tray or deep plastic food dish. It is a good idea to take an inventory during the clean-up process to make sure nothing walked off.

Corvette Edelbrock Quadrajet Carb Rebuild 013 13/28
Corvette Edelbrock Quadrajet Carb Rebuild 014 14/28

11. The main body is separated from the base as shown using a #2 Phillips screwdriver. Expect to have an entertaining time removing the old gasket material. Be mindful not to scratch any contact surfaces. Be very gentle. Scratches and scoring mean leakage.

Corvette Edelbrock Quadrajet Carb Rebuild 015 15/28

12. We’ve opted for the Edelbrock Quadrajet rebuild kit (PN 1920) for our restoration. Everything you’re going to need is in this kit.

Corvette Edelbrock Quadrajet Carb Rebuild 016 16/28

13. Our Quadrajet has been boiled out and is in pristine condition for assembly. Dunk the carburetor parts and give it 30-60 minutes of high-frequency buzz time. These parts come out looking like new. All the passages have been chased by Kleiner and we’re ready for assembly.

Corvette Edelbrock Quadrajet Carb Rebuild 017 17/28

14. The Quadrajet base plate is checked for wear and irregularities. We have a good core. The shaft bushings and throttle plates have been inspected.

Corvette Edelbrock Quadrajet Carb Rebuild 018 18/28

15. The idle mixture screws are lubricated with a penetrating lubricant and reinstalled. Gently seat these needle valves, then back them out 1 1/2 turns for the initial start-up. Proper adjustment is achieved after the engine is fired up and gets up to operating temperature.

Corvette Edelbrock Quadrajet Carb Rebuild 019 19/28
Corvette Edelbrock Quadrajet Carb Rebuild 020 20/28

16. The base gasket is installed next. This is a nice, thick gasket that will not waver in its function. Snug the screws in crisscross fashion, then tighten completely.

Corvette Edelbrock Quadrajet Carb Rebuild 021 21/28
Corvette Edelbrock Quadrajet Carb Rebuild 022 22/28

17. The choke fast idle cams and pull-off assembly are then reinstalled. The fast idle speed will be adjusted once the engine is fired.

Corvette Edelbrock Quadrajet Carb Rebuild 023 23/28

18. The main metering jets have a penetrating lubricant applied to the threads before they are reinstalled. Check to make sure the jet sizing is correct. You want factory suggested jet sizing depending upon where you live (elevation) and engine modifications, such as cam, intake and compression ratio.

Corvette Edelbrock Quadrajet Carb Rebuild 024 24/28

19. The float valve seat is installed and snugged; again, using a quality penetrating lube.

Corvette Edelbrock Quadrajet Carb Rebuild 025 25/28

20. The new Edelbrock float is installed and adjusted to specifications in the instructions. For the most part, the float level should be perfectly level with the carburetor body’s top deck.

Corvette Edelbrock Quadrajet Carb Rebuild 026 26/28

21. The main metering rods and piston are seated next. Again, you’re going to want to know jet and metering rod sizing. Ascertain the proper size before going any further.

Corvette Edelbrock Quadrajet Carb Rebuild 027 27/28

22. The main body to air horn gasket is installed along with the accelerator pump piston.

Corvette Edelbrock Quadrajet Carb Rebuild 028 28/28

23. The air horn and main body have been mated and we’re on the home stretch. The air horn screws have been snugged crisscross, then tightened. This approach prevents warping. A new fuel filter is installed next.

Photography by Leanne Kleiner

Sources

Hot Rods By Dean
Phoenix, AZ 85027
623-581-1932
www.hotrodsbydean.com
Edelbrock
Torrance, CA 90503
310-781-2222
www.edelbrock.com

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