Greg, that is what I was afraid people would look at and think it is acceptable. Even on a 2 1/2" car valve, it looked to wide. Like you ask, a sharp line is the best. A wide line like the photo is going to be a leaker. The least little speck of carbon will prevent it from closing all the way. A sharp line will crack the carbon in half, and still seal.

A couple years back, I bought a set of plans for a 1/6th scale P&W Wasp Jr engine. It uses the bronze valve guide/seat combo. Some of the guys building it complained about the valves wheezing as the engine was cranked over by hand. All reported that lapping only made things worse. These valves were cut by individuals making the engine, or by a guy that makes the valves for that engine and a couple others. They are not the precision CNC cut valves and seats you would expect in engine today, so they probably represent the quility of the parts back when the Wasp Jr was in production, and the need to lap and fit parts. That just isn't the case today.

Another thing just popped to mind. That is the ring. It used to be that when you purchased a set of rings for a car, you had to set the gaps for each ring in the cylinder it was going to be in. That is a thing of the past also. Now, if our guy who stated this thread happened to have pulled the piston out of the sleve, he may have broken the ring replacing it. That could be the source of his problems, not the valves. If that was the case, lapping the valves isn't going to accomplish much other than reduce the life of the head by several years.

Don