Motorcraft & Holley 2 Stage Power Valve 70-1000

Holley 4 barrel and Motorcraft 2 barrel two stage power enrichment valve.

Great choice for carburetor designed to use the 2 stage power valve.

Please be aware that you cannot replace a 1 stage valve with a 2 stage without replacing the valve cover with a larger one.

Price includes 1 power valve only.

When the engine is at idle the vacuum is at the highest and the power valve (enrichment valve) is closed. As the engine speeds up vacuum drops and the power valve opens allowing more fuel into the carburetor.

On a 2 stage power valve such as these, the 1st stage opens up at a certain vacuum, i.e. 7,0 HG. This is at partial power. At close to full power the vacuum drops to very low HG, i.e. .5. This is where the 2nd stage opens allowing even more fuel to get to the main circuit.

The carburetor kits that include a 2 stage power valve are using OE specifications.

For other applications you will need to test the HG by hooking a vacuum meter to the engine and operate the engine at power and full power.

Changing from a 1 stage power valve on a carburetor that requires a 1 stage, to a 2 stage power valve is not recommended. If you aren't sure of what you are doing, you could cause too much fuel to be dumped into the carburetor.