Some insightful info is available in picture form at the website;
systemsc.com\pictures.htm about the secondary injection
problem. The pictures include;

1. the small air outlet hole next to the exhaust valve guide
2. the small air inlet hole to the head from the cam housing
3. the small air outlet hole at the cam housing
4. the air connection fitting from the air pump to the
cam housing

The pictures indicate how not so easy the carbon buildup
removal process can be. They were taken at a Porsche dealer
and an independent shop both doing valve jobs on 993s.
I'll provide a followup post on what I've discovered
from conversations with Porsche techs on a later post.

Note: The four jpeg files are large (about .5M each), so
the downland time may take a minute or two.

Loren
'88 3.2

 

Loren,
Thank you for sharing these valuable info. and looking forward to your followup post.

-------------------------------
'97 blk/blk C2S

 

Sorry for large picture files. Smaller ones now "up".

http://www.systemsc.com\pictures.htm

Loren