How do I know what size power valve I need?
How do I know what size power valve I need?
To know which power valve you have, all you need to do is look at it. Each power valve is stamped with a number that indicates the correct vacuum opening point. For example, a power valve with the number 65 stamped on it will open at 6.5 inches of engine vacuum.
What happens if my power valve is too big?
Problems: The incorrect size power valve, or a blown out power valve can cause problems such as poor fuel economy, black smoke emanating from your exhaust, dark or fouling spark plugs and a poor idle. If you suspect that your carburetor has a blown-out power valve, you can perform this simple test.
What happens if my power valve is too small?
If you run too low of a power valve value, the symptoms will be a lean transition as the power valve opens “late”. You usually have a lean popping and possibly even a backfire when you punch the accelerator. It will have poor acceleration.
How do I know if my Holley power valve is blown?
A blown Power Valve acts like it is open all the time resulting in a Dramatically over rich mixture at Idle and no response when adjusting the Air Screws. If your Vacuum at Idle is say 10Hg’s you should run something like 6.5 Hg Power Valve so that it only opens when you blip the throttle when the Vacuum drops.
When would you use a power valve plug?
The answer is the power valve rating that is best for your application. This will provide idling and proper fuel flow under wide open throttle conditions when manifold vacuum seldom rises above 1 inch Hg. To correct for a manifold vacuum of 5 inches or less, remove the power valve and install a Holley power valve plug.
What should vacuum reading be for Holley power valve?
The face of this power valve has the numbers 6 and 5 on it. That means that this valve opens at 6.5 inches of vacuum. Stock engines typically have a high vacuum reading (10-18 inches at idle) and the Holley power valves with higher readings like 6.5 to 10.5 will work correctly.
How many power valves does Holley manifold have?
A 6.5 InHg power valve would open anytime the manifold vacuum is lower than this value. Holley offers multiple power valves rated at points from 1.0 to 10.5 InHg.
What makes a Holley carburetor work so well?
How to ensure your Holley carburetor is using the right power valve for your engine. Holley carburetors have a power enrichment system that provides fuel to the main power circuit during heavy loads or under full throttle situations.
Where is the blow out valve on a Holley?
Finally, most of the popular Holley carburetors incorporate a power valve blow-out protection system. This is a special check valve that is located in the base plate, expressly for this purpose. This check valve is designed to be normally open but will quickly close off the internal vacuum passage when a backfire occurs.
