The stock valve sizes are escaping me at this moment, but a typical bowl cut below the valve seat area is usually between .75-.80 of the diameter of the valve. This will help maintain a venturi shape passage into or out of the port, helping to retain a relatively high air speed through it, and not having "dead air". Also, since much of those early concepts and ideas on air flow technology have been shown to now not be considered good practices,ie... (using a shell reamer to enlarge the port opening).First,nothing is wrong with a shell reamer to enlarge an opening. But, what is does to a 235 head is that it lowers the port floor,which has been proven in modern times to not be a wise move as far as air flow is concerned. My thoughts would be to either shift the port upward while at the same time enlarging it, or stretch it from side to side,forming an oval shape while keeping and maintaining the stock floor height! As soon as I recieve my 848 head for science purposes, I will be able to show and dispell many myths regarding these early mods and show that modern technology and concepts will be the way to progress with these engines.
