Wednesday, February 26, 2014
How to Replace the Power Valve on a Holley Carburetor
Power valves on Holley carburetors are usually trouble free, but they do occasionally require replacement. Engine modifications may dictate the use of a different power valve. You may want to change your power valve if youve moved to an area that is significantly higher or lower in elevation than your previous residence. Also, power valves may rupture and require replacement if the engine backfires through the carburetor. There usually no need to remove the carburetor from the engine in order to replace the power valve.
Instructions
- 1
Remove the fuel line from the carburetors fuel bowl. Fuel line attachments vary. The most typical style is a slip-on fitting with a hose clamp. Use a screwdriver to loosen the hose clamp, and pull the hose from the carburetor. Use a rag to soak up any spilled fuel.
2Remove the fuel bowl from the carburetor. Remove the four hex head bolts that retain the fuel bowl and metering block using the 5/16-inch nut driver. Using the handle of the screwdriver, tap lightly on the fuel bowl to loosen it, and set the fuel bowl aside.
3Remove the metering block to expose the power valve. Again, tap gently on the metering block to free it from the carburetor main body.
4Unscrew the power valve from the metering block using a 1-inch wrench.
5Install a gasket on the new power valve, and thread the valve into the metering block. Tighten hand-tight plus 1/8 turn.
6Using new gaskets, reassemble the carburetor. Attach the power valve side of the metering block to the main body, followed by the fuel bowl. Insert the fuel bowl bolts into the fuel bowl, and tighten the bolts finger tight plus 1/4 turn.
7Reattach the fuel line to the inlet on the fuel bowl, and tighten the hose clamp.
Thursday, November 28, 2013
How to Find Model Numbers on Holley Carbs
Holley is one of the leading manufacturers of aftermarket performance carburetors in the United States. Holley carburetors come in a variety of different designs and functions, and you can purchase upgrades to your existing carburetor to make it work more efficiently in your vehicle. You will need to know the model number, otherwise known as the list number, of your Holley carb to order new parts for it from Holley and other aftermarket parts manufacturers. Holley uses the list number to identify their carburetors.
Instructions
- 1
Look at the right side of your carburetors choke air horn. You should see two numbers there, the top one is your List number and the bottom one is the date code location. The list number will begin with an R and consist of 6 to 8 digits. This is the number you need.
2Look for the list number on the top of the main body casting if your carburetor does not feature a choke air horn. If your list number is on the main body casting, your carburetor is probably a model 4500.
3Look up the list number on Holleys carburetor parts list. (See Resources.) You will find the model number in the column next to the list number.
Tuesday, October 29, 2013
How to Adjust the Idle Mixture on a Holley Carb
Adjusting the idle mixture of your Holley carburetor is an important procedure in the operation of the motor. The proper adjustment of the carburetor can improve your fuel mileage as well as keep the engine running more efficiently. Adjusting the two idle mixture screws of the Holley carburetor only takes a few minutes and requires only a couple of tools. Save the time and money it takes to visit a mechanic by adjusting the carburetor yourself.
Instructions
- 1
Locate the two idle mixture screws (one on each side) of the Holley carburetor and turn both screws carefully counterclockwise with a screwdriver until they bottom out and you feel resistance. Do not over-tighten the idle screws.
2Turn both screws one-and-a-quarter turns clockwise with a screwdriver to find the idle adjustment starting point. Start the motor and allow it to warm up for about five minutes.
3Remove the rubber vacuum hose from the metal vacuum port on the side of the carburetor and attach the vacuum gauge hose to the end of the port. Have someone place the car in gear and hold it still while you are adjusting the idle mixture screws.
4Turn the idle screws one quarter-turn clockwise at a time in sequence with a screwdriver until you have the highest vacuum readings for both idle mixture screws. Put the car into park and leave it idling.
5Repeat the procedure in Step 4, adjusting the idle mixture screws with a screwdriver while the vehicle is in park, until you get the highest vacuum readings. Remove the vacuum gauge from the carburetor vacuum port and reattach the vacuum hose to the port.