Let’s just say it’s the one you hear about all the time and the place home porters hit first and call them ported heads. The pinch to me is the next spot that needs addressing. Open the pushrod pinch the short turn area becomes the pinch. Address it and the pushrod pinch is the pinch again. Back and forth you can go but Dont forget the throat area that can become the pinch along the way. When you get the throat to a max of 91% of valve size then a bigger valve is needed to keep raising the cfm. For a guy that ports for a living we can quicken if the back and forth as we have been down this road before.
