As you guys may know the early holley carbs have some odd features that were quickly discontinued. The obvious outside one is the non adjustable float bowls which is pretty self explanatory. I was wondering what you guys were doing power valve and jetting wise? Do you guys go both power valves or block the secondary one and jet up like holley went to a couple years later?

Where the carbs have a secondary side power valve, my preference is to do away with the secondary side power valve and plug the opening.  The jet size increase depends upon the size of enrichment circuit holes under the power valve in the metering block.  To calculate this, I’ll determine the size or diameter of the holes, convert that to a square inch dimension and add that to the existing secondary jet size square area.  Using a chart that converts square inches of jet size to the number format, the jets are upped in size accordingly.
 
For the primary side power valve, I like to start with a #65 power valve as that’s the one that typically comes in a carb kit.  If there’s any kind of hesitation or flat spot, then a power valve with a higher number (earlier opening) may help assuming you’re not dealing with primary jetting that’s already on the lean side or a float level that’s low.

Lorena, Texas (South of Waco)