Reply to "4V CC head porting with pressed bronze valve guides."

I have witnessed many people setting-out to modify the Cleveland intake port (which is a highly developed intake port of a racing cylinder head) without understanding its design to begin with. I think it is cool that you're asking questions.

I do not know what you are referring to by the term "booster ring", its unfamiliar to me.

Never eliminate the throat in the intake valve pocket. The engineers who designed the Cleveland cylinder head knew more about cylinder head design than you or I. It is proper to have a throat (the port's minimum cross-sectional area) in that location. Smooth the throat, give it a radius, but reduce its diameter as little as possible. As-is it is 1.75" diameter, and 1.90" is the maximum diameter; there is very little room for modification or error. There is a theory that the intake valve pocket throat was cast as large as it is because it was originally designed for a 2.23" diameter valve. Its just a theory, I've never known anyone who could say for sure. Race engine mechanics/machinists I knew in the 1970s and 1980s did very little work in the intake port or valve pocket outside what I've described to you. The only other work they performed was to open-up the pocket to make it more round, center the pocket around the guide, and reduce the diameter of the guide. The valve pocket work I've described is simply detail work that was too time consuming for the factory to perform for a mass produced engine, its difficult to make a truly meaningful improvement to the Cleveland intake port beyond that.

In your picture the intake valve is shrouded at 7 to 8 o'clock and from 9 to 11 o'clock. The exhaust valve is shrouded from 2 to 4 o'clock. Un-shrouding improves low-lift flow. The canted valve geometry of the Cleveland head causes the valves to un-shroud themselves as they open ... they move away from the cylinder walls and the combustion chamber walls. But we want to achieve as much low-lift flow as possible if high output is the goal. If your only goal is a street engine with 400 horsepower don't worry about these details. Just avoid making the usual errors, like opening-up the diameter of the intake valve pocket throat too large.

If you closely examine the first picture I posted you'll see it has "3 angle" valve seat grinding.

Regards