Small Engines (Lawn Mowers, etc.): engine timing, cam lobes, push rods

Question
I have a B&S 17.5OHVthat I'm working own for someone and to get it to start, you would have to turn the flywheel back till you feel compression then try the start key. most times it would stop at next comp. I removed the engine from the frame and removed the bottom housing.I found the timming off be two teeth.As I put cam back in time I checked the valve rockers and found them very loose. the adj nuts are down all the way, one spacer on top the exhaust valve is missing. Why are the valves this way?

Answer
You can download the servie manual at the site below:

http://bgsengineclinic.com/brochures/276781SingleCylinderOHV.pdf

Did you check the push rods to see if they are bent?  A quick method to check the push rods is to roll them on a piece of glass and see if they wobble or not.  If the push rod wobbles then it it bent.

Are the push rods seated in the valve tappet.

Cams rarely jump teeth.  Are the cam lobes out of spec?

Eric