can someone explain the benifets/hazards of plugging the power valves in holley carbs. I keep hearing of people doing it but don't understand the reasons why.

 

Consistancy. Power valves open when vaccum levels reach the set level of the valve. They allow fuel to dump into the intake to counteract a lean condition. When drag racing, this can cause unpredictable ET changes. When removing and plugging power valves, the general rule of thumb is to go up 8 jet sizes to compensate for the missing power valves. On a typical DP carb, it's also better to square jet the carb for drag racing. If everything is the same size in the carb, why would you have different size jets in the secondaries than in the front? The same amount of air is going through each venturi. The carb is operating at WOT. You would want the same amount of fuel going through each venturi.

The downside of square jetting a carb is that you need 4 of each jet. This means having to buy 2 complete jet kits.

Setting up a carb for street use is totally different.