Quote:
Originally Posted by diegokid
I'll bite again, why would you need to drill holes in the first place and what would the symptoms be if someone needed to do this.
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If your engine now idles at 800rpm with 5 inches of vacuum instead of 800rpm at 16 inches of vacuum (after a cam change), it is consuming more air.
Opening the butterflies to compensate exposes the transfer slots and makes the mixture screws less responsive to uncontrollable.
It also shortens the idle/transition phase of the engine and produces off-idle flatspots etc.
Drilling holes in the butterflies allows the extra air, but you need to drill in small increments to sneak up on the optimum.
The transfer slots should have about .020 exposed when looking from underneath.