If you are going to do any work on your Holley power valve circuit, do yourself a favor and get one of these:
http://www.speedwaymotors.com/p/1240...ve-Tester.html
Use it to test your old valve to make sure that the valve is actually the problem. Use it to test any new power valve before you install it in the carb. I used to go through four to six before I found one which actually opened at the value specified on the package. Some of them were off by 50%. The local speed shop would let me test them in the store to make sure they were opening at the proper value before I paid for them.