Holley 94 power valve

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I recently bought a race car that was built in the mid 1950s, it has a flat top V8 with twin Holley 94 carburetors. The front carby was leaking fuel into the barrel on idle. When I stripped the carby I found that the power valves have been modified, the guts of it have been removed and a screw inserted to block it off.
The first of many questions, Why? Why would you block off the power valve? Could it be to stop over fueling issuses?
Apart from running rich the car runs well it does not lack power, hard to start as it does not have chokes and the float level is spot on.

Any info on what to do will be awesome

Brian