Small Engines (Lawn Mowers, etc.): valves, briggs stratton engine, dish shape

Question
could you tell me if the exhaust valve seats tight to the head on a Briggs & Stratton engine modle196702-type401501-code9304910-8.5hp. has some one removed the valves & i have now to put them back in & cant under stand that when i put the spring & then the part with the cullets in then their is like a beveled bowel & when this is fitted the valve does not seat tight i am only guessing that the dish shape bowel came from here. hope you can under stand what i mean thanks Gerald

Answer
With the valves installed, with the spring and retainer, what is you valve to tappet clearance at top dead center on the compression stroke?  Rotate the engine several times and re-check the clearance to get an accurate reading.
Are the valves new or are you using the old ones?
Let me know the clearance.
Eric