Questions and Answers

GM 350 Valve Adjustment Q. Hi, I hope you can help me with this. I got a 1988 350 TBI truck and I have some troubles adjusting the rocker arm nut. After changing the valve stem seals and "O" rings to all the valves, I adjust the valve lash as it says in the GM service manual. The truck starts but it runs erratically. Then I adjust it when the car is running, turning the nut ½ turn more after the clatter stops and the truck runs fine, but it smokes.

Then I try ¼ of turn and it stop smoking so I keep this setting, but after 100 miles of driving the intake valves number 1 and 2 start to clatter. Now I'm going to adjust the rocker arm nuts again but now I don't know if I have to keep the ¼ turn or go for more or less?

The smoke that came out of the pipe indicates that they are too tight or too loose??? I just don't know now. When I adjust the rocker arm nut again is it okay if I adjust them at idle or I have to increase the rpm??

Thanks a lot. I hope you can help me with this.
Charles

A. Chevy's specification for the rocker arm nuts are 1 turn down after zero lash is achieved. That's one complete turn after all ticking is gone. You must turn them slowly as the engine will run a little rough until the lifter bleeds down.

I would suggest turning all valves to zero lash, no ticking. Then turn all valves a ¼ turn and let it recover. Keep doing this until all are 1 turn or 360°.