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.