Carburetors and Carburetor Kits
Give Your Old-School Carburetor Some Love
When it comes to auto repair, you can easily separate the modern at-home maintenance mechanics from the classic car enthusiasts by testing their skills with a carburetor project. Most vehicles built in the 1980s and earlier rely on carburetors to feed air and fuel into their engines. Today, most personal vehicles on the road use fuel-injection engines, which deliver a more accurate, reliable and clean operation.
Your vintage carburetor sits on top of your engine to regulate the air/fuel flow using throttle blades (controlled directly by the driver through the gas pedal). The carburetor also maintains the level of fuel storage using the fuel bowl. As the throttle opens, additional air is pulled into the engine, which brings with it more fuel, causing the engine to develop more power. For vehicles with automatic transmissions, the carburetor can even manage your shift points.
To start, air is pulled into the engine through the intake manifold vacuum. As the air flows through the barrels of the carburetor (also called venturi), a vacuum is generated by the pressure drop. This vacuum generates an increase in airflow velocity, which also pulls fuel through the main jets of the carburetor. The fuel from the float chamber mixes with air before it is sprayed into the main barrel (or cylinder) of the carburetor. This is all possible because the float chamber (carburetor float bowl) is designed to contain a small amount of fuel that flows to the carburetor jet on demand.
Fine-Tuning Optimal Carburetor Operation
To understand why your carburetor is underperforming from potentially leaking fuel, it's important to know that in order for your fuel and emissions system to startup and accelerate, the carburetor must store a small amount of fuel. Because the fuel is delivered via vacuum and not injected, it is critical that your carburetor holds a couple ounces of fuel at all times.
The level of fuel inside the carburetor float bowl is adjusted through the needle and seat. When the fuel level dips below the set level, the weight of the fuel float opens the needle. Then, the fuel flows in through the port in the seat until the float rises, closing the needle.
If you notice that your carburetor is surging, your system might be running too rich or too lean. Meaning the regulation of the fuel-to-air ratio (air/fuel mix) is off. Referred to as the AF ratio or AFR, this metric is critical to the balance needed for your engine. A mix of 14 or 15 pounds of air per 1 pound of fuel (14-15:1) is ideal, meaning the optimal level of fuel and oxygen is being used. If your carburetor runs any leaner (18-19:1), you will shift from great fuel economy to a seized engine with massive repairs needed. If your carburetor is running too rich (6-9:1), your performance will suffer, and you will emit toxic black exhaust.
Clean, Adjust or Refurbish Your Carburetor
If you are experiencing the signs of a failing carburetor (hard to start, hesitation, stalling, rough idling and decreased fuel economy), a good carburetor cleaner will sometimes solve the issue. Check out the Berryman Chem-Dip Carburetor Parts Cleaner with Basket and NAPA Mac's Carburetor, Choke and Throttle Body Cleaner. Additionally, follow the NAPA guide for How to Clean a Carburetor.
When a classic car sits too long without being taken out for a spin, corrosion can cause internal parts to stick, like the throttle blades. Or the evaporation of liquid in the fuel bowl can leave a problematic varnish. Carburetor gaskets will also shrink over time. Your carburetor diaphragm pushes out fuel when hitting the throttle. This piece operates under pressure, so it is critical it does not get stuck, pinched or snagged.
It is also important to check your carburetor float for signs of damage. If it rattles when you shake it, then it is probably bad. This carburetor component should float in a glass of water. If you see bubbles rising from your float when submerged in water, then it has a pinhole leak and needs replaced.
NAPA AUTO PARTS sells all the carburetor rebuild kits DIY mechanics could need. Browse this collection of carburetor and manifold kits. Our fuel and emission system parts include the smallest components like bleeder screws, springs, spacers, seals, bolts and bushings, as well as plates, plugs and pins. Check out the power valve actuator by NAPA Echlin, which is extensively tested to ensure it is reliable as a direct-fit aftermarket replacement part.
Whether you are tinkering on a classic Chevy or maintaining the carburetor on your lawnmower or Yamaha motorbike, keep in mind that not all carburetors are the same. For instance, multiple barrels are used on high performance engines, so more air and fuel can enter the cylinders for increased acceleration. Some Italian sports car engines used multiple carburetors, one for each cylinder.
Take a Trip to a NAPA AutoCare Center
NAPA AUTO PARTS offers an extensive selection of carburetor parts and carburetor kits. However, in some cases, rebuilding the carburetor is not possible. Too many broken parts, hard to find gaskets and complicated processes are valid reasons to hunt down the best replacement carburetor for your vehicle that is already assembled. Thus, shop our top-of-the-line carburetors for sale from brands like NAPA, Edelbrock and Holley so that you don't have to go through that extensive work.
Before you start to worry about how much a new carburetor might cost, remember that maintaining clean air filters and clean fuel filters will extend the life of your carburetor and engine. If your budget isn't the issue, but you want to make sure your new carburetor investment is installed right, reach out to the carburetor specialists at a local NAPA AutoCare Center near you for a complete carburetor overhaul.