Originally Posted by kleen56
My next door neighbor states he never runs his Holley's with the power valve. He said Summit sells them and they are called block off plugs and they go in place of the original power valve. I do know you have to rejet the carb to two jet sizes richer if your going to go that route.
That's OK for a race engine, but running that kind of set up up on a street engine with richer mains will result in higher fuel consumption and emissions.
The valve in question, which today has become called the power valve because it's there to richen the mixture at WOT, used to be called an economizer valve as its presence allowed main metering to be leaned out which saved fuel during part throttle operation.
So yes you can run with out it if you richen up the mains, I rather doubt that 2 sizes up will provide sufficient coverage at WOT, one of the things engine designers do at WOT is to run the engine excessively rich, a bit beyond what's required for max power, for the purpose of providing some in cylinder cooling. The purpose of this is that it essentially makes the fuel act as if it were a higher octane, thus pushing the detonation limit up. If you run hard on the top end without this excess to the excess, you run the risk of buying some new pistons.