Classic Car Carburetor Rebuilding

Classic car carburetor rebuilding is a quick and painless process that requires little more than a few basic tools, a cleaner, and a carburetor kit. Before the advent of fuel injection in performance vehicles, carburetor rebuilding was a routine procedure, performed in garages and backyards across the country.

These days, few of us have a carbureted vehicle serving as daily transportation, but a vast majority of hot rods, race cars, and weekend toys still use carbs. As a simple mechanical device, a carb is reliable, relatively cheap, and long lasting. There is little to wear out, but dirt, debris, and deposits can take a toll, even rendering a carb inoperative. A carb kit will include the typical wear components, as well as new gaskets and seals.

Prepare First

Make sure that you clearly understand the instructions and follow them one step at a time, particularly as they apply to settings such as the float level. Do not be intimidated. It is not as hard as it looks.
Before removing any adjusting screws, screw them all the way in slowly, counting the number of turns so that you will have a starting point when you reassemble the carburetor.
Go to your auto parts store and buy a carburetor cleaning kit which will contain a solvent for cleaning the carburetor and all the internal parts, and be sure to work in a clean, well-lit area.
Allow an hour for disassembly. Let the parts soak overnight, and allow at least a few hours for reassembly, installation, and adjustment. Expect it to take longer the first time.

Here is what to do:

Remove the carburetor and place it on your worktable. Make sure your work room is properly ventilated; carburetors may let off fumes that leave you dizzy or worse.
Read the instructions outlined in your rebuild carburetor kit. Kits can be bought online or at auto parts stores. There are many diverse types of carburetors for various vehicles. Make sure to buy the kit that is right for your car’s carburetor.
Unhook the accelerator pump and take the cover off. Disassemble the carburetor by taking apart the choke and removing all the hoses and screws.
Put the entire carburetor on a clean workbench and photograph it from all angles. This will help in reassembly. Keep a supply of zip-top plastic baggies, a pen, and small pieces of paper nearby. As you remove screws or parts, make a note on the piece of paper as to what the part is, where it came from and the direction that it was installed, and put the part and note in a baggy. Take photos as you disassemble the carb; it will jog your memory in reassembly. Many parts look the same once they are spread out on the bench. Little ball-bearing seals may look identical, but the size may differ by a couple of thousandths of an inch. Do not mix them up.
Pay close attention when disassembling the carburetor so you can put everything back together again when you are done. Carefully begin to disassemble the carburetor. Make a note of the sequence of disassembly. It will make reassembly much easier. The instruction sheet that comes with the rebuilding kit will be a tremendous help in locating internal jets and passages, one-way valves, etc.
Wipe down all the carburetor’s parts with carburetor cleaner. Remember to wear your safety goggles and gloves to avoid injury.
Rinse all the parts in water and allow them to dry thoroughly. Wet parts will prevent the carburetor from running properly, so make sure that all the parts are completely dry before proceeding to the next step.
Reassemble the carburetor using the instructions provided in the kit. Hook the pump back to the body of the carburetor and connect all the hoses and choke cables. Use the wrench and screwdrivers, but do not to apply excessive force.
Replace the carburetor and start the engine.

Other Helpful Tips

Never use a drill bit to clean jets or orifices. Although it does not feel like the drill bit is removing metal, it could enlarge a jet size. Never use a steel paper clip or sand blast the parts either. If you must get into a jet or tiny passage, use a piece of copper or brass wire.

A word about carburetor repair kits: many kits are designed to supply parts for a variety of carburetors. It is less expensive or easier for the manufacturer to include the parts for several carbs in one package. Be sure that you carefully match up the parts in the kit with the parts removed from your carburetor. Often gaskets look identical, but holes or openings are not the same. Also flipping a gasket over will present a new perspective of where the holes align.

Check the float to be sure that it is not leaking. Immediately upon disassembling the carburetor, shake the float while listening for fluid sloshing around inside. After everything has been cleaned, submerge the float in hot water, and watch for bubbles that would indicate a leak. Rotate the float slowly underwater so that all surfaces are given an opportunity to be facing up. Air rises, and the bubbles will be obvious. Again, shake the float and listen for fluid inside of it.

Never paint the interior of a carburetor. If external parts are to be painted, use an Aerosol Lacquer spray paint. Lacquer is more resistant to gasoline and will not peel off or dissolve readily. Make sure that you do not get any paint in screw holes, access ports, or on any linkage that must move freely.

When you assemble and then reinstall the carburetor, tighten the screws in a pattern (opposite screws) that evenly distributes pressure. Tighten the screws a bit at a time and take at least three steps to fully tighten each one. This will help put even pressure on the flanges and will help prevent breakage.

Finally

Each carb manufacturer has slightly distinct parts and instructions so follow this instruction carefully. For the DIY mechanic classic car carburetor rebuilding process is a straightforward process and can be done easily with a few hours of careful work. The good news with these projects is that the costs are reasonable, and if your project does not work or you simply do not want to undertake the job there are companies that will rebuild the carb for you. You can check our business list for companies that do this work.