Big cam idle adjustment, Holly 4150

Yep! I did the blade drill a few times early on for moderately cammed engines.....until I got my mind right. :D

So Chrysler didn't have their minds right when they put holes in the throttle plates from the factory even on some 318 BBD applications? Sure you can get a little bypass by cracking the secondary seat screw but the vortex through the hole if positioned close enough to the idle fuel port helps aerate the mixture... Just start small. The main thing is not to expose the transfer slot at idle or you will never get a good mixture.