 Rocker arm ratios, Researching my rebuild |
|
|
|
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. |
|
|
  |
| ScottD914 |
 Jan 31 2010, 10:11 AM
Post
#1
|
|
Member  Group: Members Posts: 69 Joined: 27-December 07 From: New London, CT Member No.: 8,506  |
With all the good advice on rebuilding my 1.8L, the best was: Research, research. After selecting a crank from Demello, I turned my attention to camshafts and on the Elgin website there is an obscure reference to Rocker Ratios, but they differ from Intake to Exhaust! Who knew? I verified this with measurements and found that they are different, and what a difference it could make if they were mixed up!
My rockers measure out at a 1 : 1.32 Exhaust and a 1 : 1.39 Intake. Thanks to all for the advise and especially the suggestion for researching everything (could've been Jake). ScottD |
   |
 
|
| ME733 |
Jan 31 2010, 11:35 AM
Post
#2
|
|
Senior Member Group: Members Posts: 842 Joined: 25-June 08 From: Atlanta Ga. Member No.: 9,209 Region Association: South East States |
QUOTE(ScottD914 @ Jan 31 2010, 11:11 AM)  With all the good advice on rebuilding my 1.8L, the best was: Research, research. After selecting a crank from Demello, I turned my attention to camshafts and on the Elgin website there is an obscure reference to Rocker Ratios, but they differ from Intake to Exhaust! Who knew? I verified this with measurements and found that they are different, and what a difference it could make if they were mixed up! My rockers measure out at a 1 : 1.32 Exhaust and a 1 : 1.39 Intake. Thanks to all for the advise and especially the suggestion for researching everything (could've been Jake). ScottD .................I am intrested in how you determined the ratios. The method by which intake and exhaust was measured.......MM. |
|
|
|
| Jake Raby |
Jan 31 2010, 11:59 AM
Post
#3
|
|
Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Its a well known fact that the intake and exhaust rockers have different ratios..
You CANNOT mix up intake and exhaust rocker arms, this is due to the offset of the rocker in relationship to the pushrod cup and the valve adjuster. |
|
|
|
| ME733 |
Jan 31 2010, 12:15 PM
Post
#4
|
|
Senior Member Group: Members Posts: 842 Joined: 25-June 08 From: Atlanta Ga. Member No.: 9,209 Region Association: South East States |
QUOTE(Jake Raby @ Jan 31 2010, 12:59 PM) Its a well known fact that the intake and exhaust rockers have different ratios.. You CANNOT mix up intake and exhaust rocker arms, this is due to the offset of the rocker in relationship to the pushrod cup and the valve adjuster. .................Yes...(from above)... But I,m still curious how he went about the process,and measurements that were taken/made.MM. |
|
|
|
| ScottD914 |
Jan 31 2010, 03:23 PM
Post
#5
|
|
Member Group: Members Posts: 69 Joined: 27-December 07 From: New London, CT Member No.: 8,506 |
To determine ratio, I simply measured with my vernier calipers from center of the pivot point to the center of each side. ie valve side and push rod side. Then it's just dividing one into the other. Interesting that this critical item is not mentioned in the few rebuild books I have purchased. Those rocker assembles fall apart easily and a "newbie" like me might never know the difference until startup and the engine runs a little funny. (IMG:style_emoticons/default/confused24.gif)
|
|
|
|
| Jake Raby |
Jan 31 2010, 04:49 PM
Post
#6
|
|
Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
It is impossible to install an intake rocker on the exhaust valve and vice versa.. They are not even close to aligning.
|
|
|
|
| ScottD914 |
Jan 31 2010, 05:41 PM
Post
#7
|
|
Member Group: Members Posts: 69 Joined: 27-December 07 From: New London, CT Member No.: 8,506 |
Good to know, thanks Jake.
ScottD |
|
|
|
|
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:
|
Lo-Fi Version | Time is now: 17th May 2024 - 03:51 PM |
Invision Power Board
v9.1.4 © 2024 IPS, Inc.