I can't find any record of the model number you have quoted, on the internet Pinelli, so I can't tell you the specified tappet clearance, or direct you to an owner manual (which contains the information). In principle you can get it by going here:
http://www.briggsandstratton.com/support/frequently-asked-questions/Engine%20Valve%20Clearance/ and selecting Engine Specifications Chart.
I have found in various internet reports that many people are using 0.004" clearance on both inlet and exhaust tappets. I am fairly sure this is wrong, but they have an understandable reason. My brother has a 16.5 hp 500 cc Intek, for which the specified clearances are inlet 0.003-0.005", exhaust 0.005-0.007" according to the owner manual. By experimenting he found that the decompressor stopped working when the exhaust tappet clearance was 0.008" or greater. He now sets it to mean specification (0.006") and has no problems - but he knows he will when that clearance increases just slightly. Internet reports say that the tappet clearances continually increase on that engine, hence Briggs insisting that tappet clearances must be checked once per year.
The problem with the popular practice of setting the exhaust to 0.004" is that it is below minimum specification and might therefore lead to a burned exhaust valve.
