Shiming Valve Springs

[devin3200]

Hello Folks, i was wondering if anyone can tell me if One: Is shimming your valve springs a hard job( ie with the head on?) and Two what is the procedure to do so. I believe i need to add a shim or two to my valve springs. I'm getting a tapping at the top end and the engine runs rough. I have done the valve job, but i thing i need a few shims.
Also are the shims the washers at the bottom of the spring? Or are the type that stick under the lifters? I see washer types currently but some parts houses are showing the under lifter type buttom design. Any help thanks.

[PA_944]

Your car should not need shims as it has hydraulic lifters.

[alfadoc]

Shimming valve springs and shimming lifters serve two very different functions. Valve spring shims are used to modify the spring pressure. Shims between lifter and valve stem, as you mention,are used on cars with solid lifters to set the lifter to cam lobe clearance, a la Alfa Romeo. A 944 has hydraulic lifters, so no shims are used.

I would suggest doing some reading and research on basic cylinder head theory and construction before delving into any more repairs.

[devin3200]

Thanks to all who responded to my question. I was under the impression after talking to my local porsche shop. That shims would be needed to solve the tapping noise. So i will do some more research before going back into the top end again. Thanks