You really should post the model number of the engine you are talking about as there are multiple engines that could fit your description.

Assuming it is one of the OHV engines, did you let the push rod get out of the cam follower socket? Did the exhaust move before yo adjusted the valves? IF not, the camshaft may be bad. I have a test to see if the compression release is working as well as detailed instructions on adjusting the valves IF you would like them. Address below, remind me, model number and what you want.

Walt Conner
wconner5 at frontier dot com

The engine is a 311700 B&S 17HP in Poulan Pro riding tractor. A 1999 model. Yes the pullrod out when I changed the adjust nut. I don't if move before ajusting
It run ok. The adjusted nut was broke, just the around set screw. The was little loose. I think now the worked when adjusted them. I will run comprssion test tomorrow.
May be the pushrod is not in tappet.

Ifound my book, model no. PPR1742STA Thank you

Well, for tearing engine down I replaced the pushrod I'd
got in case I needed it. Everything worked. Thanks for input, got me thinking.