Holley came out with the first modular carburetor, the 4150, back in '57. By '65, the 100,000,000th carburetor came off the Holley assembly line. Today, Holley still makes the 4150, heck, it even makes hopped-up versions for everything from drag racing to rockcrawling. With times getting tough, a brand-new shiny carb may be out of reach for some enthusiasts, but a decent swap meet find may not. There always seems to be a guy at the swap meet with stacks of them ready to be fixed up.
One major trend that most Holleys have fell victim to is the removal of the choke system. Some even had the choke tower machined off completely. Most were ditched as guys tried to squeak out every ounce of power they could for lower quarter-mile times. While some gains can be found hacking away chunks of the main body, it isn't worth losing the choke unless the truck is a drag-race-only vehicle. This story is going to show that a carb can be brought back to fully functioning condition with minimal work.
Holley has an extensive list of replacement parts for those cannibalized carbs as well as upgrades to make the carb a little easier to tune. Also added to the mix are these cool quick-disconnect fuel inlet fittings made by Jiffy-Tite. The Quick Connect Fluid Fittings are available for use with fuel, as well as oil and water systems. Fittings are available in a variety of thread styles, and once installed, you can unhook the fuel lines by pulling back on a collar, much like the fittings on your air compressor hose. The fittings will keep the fuel from running out all over the place when separated thanks to small check valves inside. You can easily swap your street carb for a track carb with these fittings. Holley, Demon, and Carter carbs are covered right now with more to come.
What's In The Box?
After calling the Holley tech line and giving the tech the serial number of my carb (stamped on the choke tower), the guy on the phone gave me all the part numbers I needed to install an electric choke and upgraded float bowls with glass sights. I also picked up the new Jiffy-Tite quick disconnect fittings so swapping carbs later will be a snap.
Part One: The Float Bowls
Here are all the parts that came with the float bowl upgrade. The box not only contained new center-hung float bowls, but all the gaskets needed for the swap. I will reuse my floats and needle and seat assemblies because they were in great shape.
 |  |  1. To start, I removed the...  1. To start, I removed the four bolts holding the old bowl to the metering block and tore down the accelerator pump. Since I recently rebuilt the carb, none of the gaskets got stuck, which was a bonus. Here, you can see the rubber umbrella going into place for the accelerator pump. Once the umbrella was in, the pump went back together just like you see it on the table: spring, diaphragm, and then the housing. |
 2a. With the pump out of the...  2a. With the pump out of the way, I grabbed the old bowl and removed the two flathead screws holding the float in place (2a) and transferred it to the new float bowl with the same hardware (2b). | 
2b. |  3a. Then, I transferred the...  3a. Then, I transferred the needle and seat assembly (3a) and set it to the proper level with this gauge my uncle Dean (3b). If you don't have a gauge, just invert the fuel bowl and turn the adjusting nut until the float surface lies parallel to the fuel bowl casting surface underneath. That should get you close enough to start the truck and adjust it while it is idling. |
3b. |  4. With everything ready,...  4. With everything ready, I installed the new float bowl with the new gaskets provided in the kit. | |