mullinax95,
They are the factory valves as you know in the late 340 and all 360 heads. The factory valves are good as long as you keep the spring pressures reasonable. I've been buying them for about $10.00 ea. from the aftermarket suppliers, and they seem to be a better quality piece than what they use to have. And I dont have and havent had any problems with them so far, but I'm sure theres always a first time.