Is there any adjustment on the tappets when fitting new valves? I can't see anything in the manual or parts catalogue. Are valve clearances measured at all?

 

anyone?

 

Hydraulic valve clearance compensation....No adjustment....

 

As jpflip correctly pointed out there is no adjustment as the valve lifters are hydraulic and self-adjusting.

There can be another "adjustment" however.

If one fits new valves, this can involve refinishing the valve seats.

With new valves and seats that have had some material removed this could have the valve stem height higher than was with the original valves installed.

There could be a callout for the height of the valve. The new valve might have some excess material on its stem end that can be removed to bring this height into spec. This has to be done carefully to avoid any overheating of the tip as it is a real hard metal heat-treated to avoid mushrooming.

While the valve lifters are hydraulic and self-adjusting with no lash or clearance they have a finite amount of clearance they can accommodate. Thus the desire to have the valve stem height within spec.

However, I have no detailed info on this as Porsche doesn't publish engine info to this detail.

What one can do is before the valve job, before replacing the valves, is take valve height measurements and try to get the new valves as close to this as possible. But hogging out lots of valve seat material is to be avoided. If the valve stem can be ground down there is not that much adjustment available.

Besides sinking the valve deeper into the head/port doesn't help flow.

 

Thanks guys, much appreciated!