Restoration of an Olympia Cremina - Page 16

#151: Post by **opifan64** » May 28th, 2011, 9:52 am

Wow! Gorgeous restoration.

#152: Post by **Possepat** » December 29th, 2011, 11:27 pm

HB wrote:A Swiss engineer wouldn't dare leave behind holes as part of the casting process, so it's safe to assume they serve some useful purpose. I'll go for either (a) extending preinfusion, (b) reducing the puck temperature shock, or (c) both. Essentially I'm guessing that it's a poor man's expansion chamber, i.e., a space for the initial hot water to go, allowing the group a few extra seconds to stabilize without scorching the top of the puck.

the holes are used quite commonly with lip seals they allow water to preload the seal and push it out against the cylinder wall. 4 holes to preload the downstroke seal, 4 to preload the upstroke seal.