v alve guides
 

A long time a go I used to race Formula Vees and rebuilt a lot of VW engines and I always changed valve guides. I always used a reamer to open up the guides a little bigger so to keep the valve from sticking in the guide. For the life of me and getting older I can not remember how much bigger I reamed the guides . I am rebuilding a porsche 2.0 engine and have replaced the guides. Can someone tell me how much bigger I need to go on the guides
Thanks