what would 2 small of a power valve cause ? could it cause idle air mixture screws to be un responsive? any one please elaberate. thank you :confused:

Originally posted by motown/malibu:
what would 2 small of a power valve cause ? could it cause idle air mixture screws to be un responsive? any one please elaberate. thank you :confused: =
No ;)
Power valves are not a jetting device in regards to 'size".
Think of it as an "on, off" main jet.
It adds fuel to the main circuit via the PVCR channels when open & allows you to run on just the jet during cruise & light throttle when closed.
The idle mixture screws usually become unresponsive because the throttle blades are too far open.

Hello,

As Mike said....the throttle blades are too far open.

The idle mizture screws control fuel discharge at idle. They are designed to work when the throttle blades are closed, resting on the idle speed screw. If the blades are open too far at idle, you are beyond the idle mixture discharge circuit....so adjusting the mixture screws is useless.

You can get your idle mixture screws to work by closing your primary throttle blades with the idle speed screw. If the motor does not like the primary throttle blades closed, you can open the secondary blades a bit to help the engive breathe at low speed / idle. The secondary blades rest against a set screw that is screwed in from the bottom of Holley cards. Remove the carb and screw the set screw in from the top of the base plate so you can get at it when you re-install the carb on the engine.

Once you have the primary and secondary blades in proper position, the idle mixture screws will work again.

....Joe

I have a question guys...If the throttle blades are open too much and you need to close them, how do you get the desired idle speed?

Use the secondary idle stop screw; or in extreme cases (way too much motor with way too much cam and too small of a carb) you can drill little holes in the throttle blades.

Increasing the initial timing will raise the idle speed and allow you to close the blades.

Also, if you replace the secondary set screw with a hex set screw you can adjust it on the engine with an allen wrench.

okay thanks guys will try that . already have holes they come that way on the new hp ..