We all do it to some extent: get the car we want, then other things getin the way ... like the rest of your life. The bottom line is that yourprized Corvette sits entirely too long with no attention. You go out tostart it and the battery is dead or the fuel is stale. Then you let itsit a little longer, allowing more water to condense in the fuel systemwhile you spend time deciding what to do about the battery.
This is a wake-up call for those of us who let our cars sit in thegarage too long. A customer recently told me that his mid-year Corvettehad an underhood fire because the carburetor had flooded, fuel spilledout through the vent tubes on top of the carburetor, a spark occurred,and up in flames it went. The worst part was that the car was in thegarage when the fire occurred. Luckily, it was in Neutral so he pushedit out of the garage and used a fire extinguisher to end the disaster.
This, then, is where we begin, as this unlucky customer dropped off his'66 Corvette for repair. After reviewing the remains, it was apparentthat many moons had passed since the mid-year was driven regularly. Thiscar was driven during many northern winters, then left to sit for a longtime.
Inspecting The Tank
After 30-plus years, the fuel system has to be full of rust and/orwater. This system is the most important to maintain to avoid fires andengine damage from fuel-flooded engine crankcases. Checking the fuelsystem first is smart business. Sure enough, the fuel tank and fuellines had severe corrosion internally and externally, and also containedsome water.
Upon further inspection, the fuel tank had one original fuel-tankretainer strap and a piece of cable to hold the other side to thechassis. Opening the fuel filler revealed corrosion across the bottom ofthe fuel tank where water had accumulated. When water accumulates in thefuel tank, it's usually just enough to cause erratic engine operation.Ultimately, if it isn't attended to, your car won't start and the entirefuel system will be saturated. Quanta Industries has an A.O. Andersenfuel tank that fits the original tank location. It makes sense to usethis tank instead of sealing the original fuel tank.
Inspecting Fuel Lines
The original steel fuel line that runs from the fuel tank to the fuelpump had been replaced in several sections with 3/8-inch rubber hose.The hose was drooping in areas that could allow a catch point and wasfull of cracks. When rubber hose starts to check (crack), it can breakat any time and cause a major fuel spill or fire. Original steel fuellines will corrode from water coursing through them and will requirereplacement. As we moved toward the front on our car, the fuel pump,pump-to-carburetor fuel line, and carburetor required replacement oroverhaul.
Fuel pumps use check valves to control fuel intake and exhaust flow.Rust particles can prevent check valves from closing, rendering a fuelpump useless. Carburetors accumulate rust particles and water. Water inthe fuel bowl can cause erratic performance. Rust particles can be sominute they can fit through a fuel filter. The small particles build uparound the main fuel jets, causing a lean fuel condition.
Since water is heavier than fuel, it sits in the bottom of thecarburetor fuel bowl, corroding the aluminum or pot-metal casting. Waterin a Holley carburetor does more damage because of the paper gasketsthat seal the fuel bowl and metering plates. The gaskets soak up thewater-causing corrosion over the entire gasket area. Most of the time,the corrosion is so severe that end-mill machining will not clean it upcompletely.
Rochester and Carter carburetors corrode, but usually they can becleaned up with a Dremel tool and plenty of patience. When I have acustomer car with an original carburetor, I suggest replacing thecarburetor with a new unit and preserving the OE carburetor. There isnothing quite like the feel of a new carburetor. Remember, more drivingand less garage time will prevent costly repairs and aggravating engineperformance.
Fuel System Action
I notified the car's owner that his fuel system would require extensiverepairs. The fuel tank, fuel-tank retaining hardware, fuel-sending unit,and all fuel lines required replacement. The fuel pump and carburetorwould require overhaul or replacement. The most costly repair was thelabor related to the fuel-tank-to-fuel-pump steel fuel-line replacement.
The fuel line was in such bad shape that complete replacement was theonly way to repair the system properly. In some situations, I have usedsteel line and inverted flare fittings to repair a small section ofrotted steel line if it is accessible. The fuel line on the '63-'67Corvette goes through the rear section of the passenger-side framerailat the kick-up. Replacing the entire fuel line requires body removal orat least raising the body 6 inches from the frame.
I decided to remove the body to replace the fuel line after checking thecondition of the body mounting bolts and caged nuts. It's a good idea tonote how many shims are at each mount for later installation. Look atthe door gaps before doing any body movement, as this will aid in shimreinstallation later. The caged nut uses a light-gauge metal cage tocapture the body-mount square nut, allowing body-mount-bolt installationand tightening. Unfortunately, the caged nut gets smaller as corrosionprogresses and the cage gets deformed when the nut spins. The rearbody-mounting bolts go through the bottom of the mount into the bodyarea. The rear body-mount caged nut is in the corner on the outside ofthe convertible car rear deck hinge and spring assembly. The coupe hasthe same caged nut in the rear corners. The caged nut assembly sits in awell that lets water build up and submerge if there is any water leak atany time in convertible cars.
The first thing to do when removing the body-mount bolts is soak thecaged nuts with rust penetrant the day before attempting to remove anybolts. The body mounts were deteriorated and the body-mount caged nutswere spinning. It's rare to find caged nuts that allow bolt removal evenwith a good drenching of PB B'laster rust penetrant. Once the caged nutsspin, there are a few choices for removal. A reciprocating saw, a smallair-powered reciprocating saw, and an air hammer work best with theleast damage to the body or frame. A torch is not recommended, as thebody is just too close. I decided the body-mount brackets with the cagednuts should be replaced because the cost is reasonable and doing sorequires less labor.
Removing the body requires removal of the fuel tank, bumper, bumperbracket, rear closeout panel, lower valance panels, seatbelt frame tobody cables, emergency brake cable, steering column, clutch linkage,lower closeout panel behind front tires, tachometer cable, speedometercable, shifter ball, sill plates, master cylinder, radiator hoses,heater hoses, throttle linkage, and oil-pressure line. Additionally, theengine wiring harness must be disconnected from the engine components.It's much easier to remove the fuel tank, then the rear bumper andbrackets. Once the body-mounting bolts are removed, lifting the bodyworks well with a four-post lift on the outer rail behind the lowervalance panels. There is a strap assembly available that hooks onto theouter rail and uses an overhead lifting device. Look carefully at theouter rail before applying any load. The outer rail at the rear is wherethe No. 3 body mount sits. If there is any corrosion damage, the railcan be weak. On this car, the No. 3 body mount on both sides did notrequire bolt removal because the rail was so badly corroded.
Once the body was removed, the caged nut brackets were cut off, the fuelline was removed, and the frame was cleaned up. The caged-nut bracketswere replaced and welded on. A coat of Ospho rust treatment was appliedto the frame. Once the rust treatment was dry (usually 24 hours) a coatof zinc-chromate primer was applied. A final coat of PPG DP-90 semiflatblack paint was applied.
Install the new fuel line, then make sure the caged nut 7/16-14 threadsare clean before lowering the body. Install the body-mount cushions asper instructions before lowering the body. The body-mount kits have goodinstructions with illustrations, so watch for correct positioning. It'sa good idea to put Never-Seize on the body-mount bolt threads beforeinstallation. Check body-to-frame alignment with the body-mount holeswhere the sill plate sits on the driver and passenger side. Be sure toinstall the body shims in the same location and check door-gap alignmentwith the chassis on the ground. I usually roll the car back and forth,then let the chassis settle overnight to see where the chassis flexmoves the body. It's not a good idea to stress the body to make a doorgap look better than it did originally. Cracks can occur if any majorchanges are made.
Now all of the items that were removed for body removal are reinstalled.The fuel tank, fuel pump, and pump-to-carburetor fuel line will beinstalled next.
Finally, I removed the carburetor and checked for contamination. At thatpoint, a determination will be made whether to overhaul or replace.
Before connecting the carburetor fuel line from the fuel pump, turn overthe engine for a while with a container to catch the fuel from the fuelline. This will flush out any contaminants that may be in the new fuelline, fuel pump, or sending unit. After the fuel system is restored, allthe fluids will be changed.
No matter what year your Corvette is, it is exciting to drive. So, whenwas the last time you drove your Corvette?