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Motorcraft & Holley 2 Stage Power Valve 70-29 (8hg, 1.5hg)
Motorcraft 2 Stage Power Valve 70-29 (8hg, 1.5hg)

Motorcraft & Holley 2 Stage Power Valve 70-29 (8hg, 1.5hg)

Your Price: $24.95
1st stage 8Hg, 2nd stage 1.5Hg
Part Number: 70-29
Availability: In Stock
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Holley 4 barrel and Motorcraft 2 barrel 2150 two stage power enrichment valve. 1st 8Hg, 2nd 1.5Hg

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


TESTING VACUUM FOR POWER VALVE SIZE
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.

TECHNICAL HELP

Please be aware that you cannot replace a 1 stage valve with a 2 stage without replacing the valve cover with a larger one.
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.
Be sure the gasket is centered.
If the power valve has a recess for the gasket, then the gasket must fit into the recess.
Spray the gasket on both sides with silicon spray lubricant.
Spread a thin coating of Permatex gasket maker around the edge of the gasket. Do not get any on the face of the gasket. This will help keep fuel from leaking through the gasket.

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