As adjunct to the How to change and clean Weber DCNF main jetting' (, thought I'd post this easy 'how-to' with photos on Weber DCNF accelerator pump jetting. To ensure that when the throttle is opened quickly, the air/fuel (A/F) mixture does not go too lean, carburetors accelerator pump a brief squirt of fuel into the barrel until the main circuit catches up. In the Weber DCNF carburetor, there are two things meter the strength of this pump shot: an accelerator pump cam and accelerator pump jet. Db2 offline backup script windows applications. Other Weber carbs have an accelerator pump by-pass that aids in controlling pump shot richness, but this is fixed in the DCNF carburetor. Accelerator pump jets for the carbd street 308 are typically sized at 45, although some later cars may have 35. Racing 308s may have as large as 60. Accelerator Pump Cam Part # “White” pump cam for model 4500 DOMINA T OR carburetors. Profile design gives a quick, early shot of fuel but it does not empty the pump. Accelerator Pump Cam Part # “Yellow” pump cam for model 4500 DOMINA T OR carburetors. Profile design delivers an early fuel shot and continues until the pump empties. Jun 8, 2009 - HOLLEY ACCELERATOR PUMP CAMS heres a needle and seat fuel valve. The pump nozzle screw, lift off the old nozzle and install the new. When you look down the carb throat you will see the jets sticking into the barrel from near where the barrels come together. You can watch them squirt when you advance the throttle to see if the pattern and amount look the same. To change, clean or inspect these jets if you have a flat spot on throttle opening, first remove the air box and velocity stacks (air horns) using your ever-handy 8mm socket or Craftsman ratcheting wrench. Using a 17mm wrench, remove the fuel feed hose (watch the gaskets!!). Next, using a screwdriver, unscrew and remove the tops of the carbs gently as not to bang around the float and easily set them aside. You will see a single brass screw holding the dual pump nozzles near the tops of the air corrector jets. Unscrew this gently and be mindful there are two small metal washers on each side of the nozzle assembly. ![]() These can be cleaned with carb cleaner and compressed air. NEVER use something to poke in the jet as it can lose its calibrated size (stamped on the jet body). Using new gaskets, re-assembly is the opposite of disassembly. Before putting the airbox back on, turn the key to the on position without starting the car and letting the fuel pump run filling the carbs with gas. Kirsty exercise bike instruction manual. Check for leaks around the carb top and fuel line attatchment (called banjo fittings).
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