Smaller Carburetor?
Q: I have a question about a 1986 Fleetwood 22-foot motorhome that was given to our family two years ago. After using it on a couple of short trips and one longer trip out east, I would like to know if it is possible to change out the four-barrel carb to a two-barrel. It has a big GM 454-cubic-inch V-8 with a ThermoQuad carburetor. I know you can get two-barrel carburetors equal to the specifications of a four-barrel, but my question is, would it increase my mileage? I have worked on a lot of cars and I am capable of doing this myself.
Stephen Johnston
Omaha, Nebraska
A: First, are you sure your motorhome has a ThermoQuad carburetor? From what I recall, older 454-cid V-8 engines were equipped with carburetors from Rochester.
To answer your questions, changing carburetors would be a big expense, since you’d have to change the intake manifold as well as the carburetor, and it may not meet antismog requirements. Plus, it could create problems when climbing long hills and passing other vehicles, and hinder acceleration. Although the possibility is fairly remote, it also could cause internal engine problems as a result of fuel starvation.
For readers who don’t know how a four-barrel carburetor works, here’s a short explanation. Think of the four-barrel carburetor as a pair of two-barrel carburetors. The engine normally runs off the primary (and smaller) two barrels until you kick in the secondaries (larger barrels) by depressing the accelerator. Therefore, you could virtually change to a two-barrel carburetor by changing your driving habits; simply don’t depress the gas pedal enough to open the secondaries. And slow down. If you haven’t done so already, you also could add a dual exhaust system to allow the engine to breathe better.
Battery Corrosion
Q: I own a 1998 Beaver Patriot with a 330-horsepower Caterpillar engine, and I have a concern in reference to constant acid buildup on the battery cable ends. What can be done to rectify this problem? I clean the cable ends constantly, only to notice further buildup in a short period. Also the batteries, both engine and coach, seem to require constant filling. This was never a problem on the gas unit I owned. Any suggestions would be greatly appreciated.
Ralph Mack, F193162
Durham, North Carolina
A: Here are a couple of thoughts. Corrosion is caused by battery acid, and that is why most sealed batteries don’t have an issue with corrosion around the terminals. On flooded-cell batteries, the acid is being transported into the air from the venting of gas and vapor during the charging process. Some corrosion is inevitable, but the more the battery vents, the more corrosive opportunity the terminals have. Since you must irrigate frequently, the contributors could be: overcharging, because the charging system needs to ramp down to float; overfilling the cells, as too much water will cause more venting; or the batteries are getting too hot. There needs to be sufficient ventilation in the battery compartment. A protective terminal spray also will help, but this is treating the effect, not the cause.