Valve adjustment issues., Weird... |
|
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. |
|
Valve adjustment issues., Weird... |
Bob L. |
Aug 13 2012, 12:41 PM
Post
#1
|
Senior Member Group: Members Posts: 848 Joined: 7-August 11 From: Austin TX Member No.: 13,411 Region Association: Southwest Region |
I have been cleaning a new to me engine to put in my '73. It's a '76 2.0 D-jet- stock valve train. After re-installing the rocker arms I went around and adjusted the valves using Cap'n Krusties' Rocking method and it seemed to be going fine. After getting all valves done I decided to check them all again. This is where it gets weird. While checking one rocker/valve I notice that another one seems to be looser than it was when I set it. I understand how it could get tighter as the cam rotates and closes the valve.
According to the rocking method the Rocker being adjusted is on the backside of the cam (opposite the lobe) and therefor as loose as it should get. So, why Can I measure a greater gap when It should only be able to get smaller? (IMG:style_emoticons/default/confused24.gif) Apparently I'm not the only one who has run into this. Also, I get different gap readings when using the piston at TDC method. Some are the same, some loose or tight. This is my first time working on the rockers/valves, FWIW. Let the learning begin(continue)! |
Dave_Darling |
Aug 13 2012, 03:22 PM
Post
#2
|
914 Idiot Group: Members Posts: 14,991 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
In my case:
Engine still out of the car, with the transmission still on it. Valves adjusted at TDC, according to the mark on the flywheel. Re-checked valves using the opposite-rocking method. Any valve whose counterpart on the same cylinder was open had greater clearance than was set at TDC. I never could get an answer as to why that might be. The only thing I could think of was that the rocker shaft was moving. But I did torque it down to the correct spec, 10 lb-ft. I'm waiting to hear any good answers as well! --DD |
Valy |
Aug 13 2012, 04:37 PM
Post
#3
|
Senior Member Group: Members Posts: 1,677 Joined: 6-April 10 From: Sunnyvale, CA Member No.: 11,573 Region Association: Northern California |
In my case: Engine still out of the car, with the transmission still on it. Valves adjusted at TDC, according to the mark on the flywheel. Re-checked valves using the opposite-rocking method. Any valve whose counterpart on the same cylinder was open had greater clearance than was set at TDC. I never could get an answer as to why that might be. The only thing I could think of was that the rocker shaft was moving. But I did torque it down to the correct spec, 10 lb-ft. I'm waiting to hear any good answers as well! --DD Worn out cam bearings? The rocker shaft is not the only thing that can move... |
Lo-Fi Version | Time is now: 2nd June 2024 - 12:08 PM |
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 ... |