Piston / Valve clearance on a /6 |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Piston / Valve clearance on a /6 |
ahdoman |
Sep 15 2008, 11:51 PM
Post
#1
|
It's phonetic...Ah-D-O-Man (Audioman) Group: Members Posts: 667 Joined: 7-November 05 From: Santa Clarita, Ca. Member No.: 5,084 Region Association: Southern California |
I've been reading Wayne Dempsey's "rebuilding your 911 engine 1965 - 1989" book. Really good stuff! However, I do have one question in relation to piston & valve clearance; If I understand him correctly you add the copper shims at the bottom of the barrel to adjust deck height clearance. Does adding copper shims also lower the compression ratio as well? If so, is there any ratio formula for shim thikness to ratio decline? Then if you achieve proper deck height would piston / valve clearance only change if a head was machined?
|
Cap'n Krusty |
Sep 16 2008, 12:25 AM
Post
#2
|
Cap'n Krusty Group: Members Posts: 10,794 Joined: 24-June 04 From: Santa Maria, CA Member No.: 2,246 Region Association: Central California |
Yes, the CR drops as shims are added. However, you also must consider the reduction in chamber volume that results from surfacing the head. Lotsa math here .................. To reduce the problems caused by stacking shims, thick ones are available. Generally, a good machinist will record the cut and you simply add the appropriate shims. Remember, all the head cuts MUST be the same so all the barrels end up having the same deck height. The Cap'n
|
Lo-Fi Version | Time is now: 1st June 2024 - 01:48 AM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |