Square or staggered jets.

[mopartodd]

I've been curious how many people out there square up their jet sizes on Holley mechanical 4-bbl. carburetors. What's the reason for doing so? Or not doing so? Again this is on a mechanical carb.

[B1owner]

Originally Posted by mopartodd

I've been curious how many people out there square up their jet sizes on Holley mechanical 4-bbl. carburetors. What's the reason for doing so? Or not doing so? Again this is on a mechanical carb.

Holleys have power valves on the primary side so they get extra fuel through power valve channel holes in the primary metering block when the power valve opens up, as this helps fuel economy. The secondary side doesnt use power valves (some obscure models and a few dominators did) so to make up for not using a power valve it gets more main jetting.