tapping on top of engine. valves??

Hi all,

i have a 1968 sears super 12. model number 917.25311. It has a 12hp. tecumseh model number 143.582132 in it. There seems to be a tapping sound coming from the front top part of the engine. Im almost positive its the intake valve, but not 100%. Could it be something else?? I took the valve cover off on the front of the engine to check the valve gap between the stem and lifter. Tecumseh manual says intake should be .010 and exhaust should be .020. The exhaust gap is fine, but the intake gap is at .019. Sounds like that may be the problem?? If it is the problem how would i go about adjusting the gap, bringing it closer??

Thanks for your help
Alan