[Gunter]

Originally Posted by Brotok

I made a typo in the original post (now corrected): Porsche recommends re-adjusting the valve clearance after 30 minutes, not the timing - my apologies. This is in a short paragraph on page E79 of the workshop manual, and pretty much states what I have reproduced here.

Does it actually say in the workshop manual to adjust the valves at 0.25mm for a break-in?

There is some logic behind ignoring Porsche's recommendation to re-adjust valves after 30 minutes of running the engine, and I doubt that this would be the first time that Porsche's recommendation is controversial. The logic follows:

Nothing wrong with checking the valve clearance per recommendation but I cannot buy into setting them two and a half times normal clearance

- It is dangerous to run valves that are too tight, e.g., tighter than 0.1mm
- It is not dangerous/harmful to run valves a bit too loose, e.g., slightly less than 0.25mm (actually, 0.25 is the clearance used on many BMWs for normal operation).

Appels and oranges. Different engine, cams, overlap. Valve-lash for exhaust valves is more critical than the intakes but 0.25mm is not just a bit loose, it's over the top. Did you time the cams with 0.25 or 0.1mm?

Does anyone agree?

Anyone ever went with very loose valves for a break-in?

Thank you for bringing all of this up

Input, please.