Hi,
I have been dealing with a 4160 Holley carb for about 4 years now. It sits
on a 1968 429 cid. I live in Denver 6000+ above sea level. I have tuned
my carb using the holley manual and a vacuum guage and have dropped from a jet size of 69 to 63. I have changed the power valve to be half my vacuum. I have turned the idle jets in and the truck stalls like it should.
I open them up 1 1/2 turns to start over again......and still I am
too rich at idle. Can anyone give me a couple of pointers on what to do next? Please.

 

Here is a little trick. Open the secondaries up a little so more air gets in the carb and the motor tends to get leaner. That does it.
fixed.

 

Money says you have a blown power valve. All it take a is mini back fire thru the carb. To test just screw the idle mixture screws in until it dies, if you get to a half turn or less then you have a bad power valve. Oh and don't go screwing with the secondaries.