High-Performance Weber Upgrade Part 4

Next up is to increase the size of the fuel-inlet hole located on the front of the carb's top cover. Because of the increased demand for fuel, a half-inch bit allows for more fuel to flow into the chamber.

Before and after. The top carb cover has been converted to allow for an increase in fuel flow. As well, the bottom has to be drilled out too.

Sometimes intense vibration can rattle loose the brass "spring-key" clips that retain the auxiliary venturis (boosters). Once this happens, they can twist and cause a leak. To combat this, the stock-location hole is enlarged, threaded and a set screws are added to secure the booster in place.

Once all of the machining is completed, the carbs need to be cleaned of shavings, dried and reassembled. Jack chooses a clean well-lit environment to lay out the parts before assembly.

The throttle shaft is put in place and the new butterflies are attached. The throttle shaft bearings should be re-greased. The pin to the accelerator pump lower arm and spring are set in place.

New 48mm venturis are dropped into place, and the old boosters are set on top.

Blue Loctite(R) is used on the new booster set screws to hold them in place.

Because of the larger stacks that will be installed, 8mm hex jet extensions are added to the main jet for easier access. Larger idle jets are added (70); the accelerator pump shaft is replaced (make sure to grease the pump pushrod); a 3.5mm glass ball high-float needle valve is installed.

Not shown is the adjustment made to the float to allow for the larger needle valve. It is set up from stock 0.210mm, and the fulcrum pin is screwed back in place. The carb body cover is placed on top (don't forget to replace the gasket), along with the fuel filter and the brass plug.

JayCee Enterprises Pro Stock Stacks are bolted into place for better air flow. They come in red, blue or satin aluminum.

Once complete, you've got a custom set of carbs that will be able to provide your engine with the air and fuel it needs.