 tolerance when cutting pushrods..... margin for error |
|
|
|
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. |
|
|
  |
| mike373 |
 Aug 8 2007, 04:44 PM
Post
#1
|
|
Member  Group: Members Posts: 198 Joined: 3-August 05 From: san diego, ca Member No.: 4,536  |
Ok..... So, I did the rocker geometry, and got my adjustable pushrod dialed in and locked. It has the same exact ball ends as the ones im using (manton chromoly).... so there will be no guessing with regards to radius of the ends. I took everything to my machinist, and he said that because his lathe bit was on the dull side.... from cutting flywheels.... that he could only get them within .008 or .010 from the adjustable pushrod I gave him. MY QUESTION.... What is acceptable tolerance....or margin for error.... before the geometry starts getting affected. I took these to a couple other machine shops, who said they could get it within .005 . This is crazy making.
Mike |
   |
 
|
| mike373 |
Aug 9 2007, 12:04 AM
Post
#2
|
|
Member Group: Members Posts: 198 Joined: 3-August 05 From: san diego, ca Member No.: 4,536 |
QUOTE(mike373 @ Aug 8 2007, 02:44 PM)  Ok..... So, I did the rocker geometry, and got my adjustable pushrod dialed in and locked. It has the same exact ball ends as the ones im using (manton chromoly).... so there will be no guessing with regards to radius of the ends. I took everything to my machinist, and he said that because his lathe bit was on the dull side.... from cutting flywheels.... that he could only get them within .008 or .010 from the adjustable pushrod I gave him. MY QUESTION.... What is acceptable tolerance....or margin for error.... before the geometry starts getting affected. I took these to a couple other machine shops, who said they could get it within .005 . This is crazy making. Mike No one....Eh??? |
|
|
|
| orange914 |
Aug 9 2007, 12:09 AM
Post
#3
|
|
http://5starmediaworks.com/index.html Group: Members Posts: 3,371 Joined: 26-March 05 From: Ceres, California Member No.: 3,818 Region Association: Northern California |
QUOTE(mike373 @ Aug 8 2007, 11:04 PM) QUOTE(mike373 @ Aug 8 2007, 02:44 PM) Ok..... So, I did the rocker geometry, and got my adjustable pushrod dialed in and locked. It has the same exact ball ends as the ones im using (manton chromoly).... so there will be no guessing with regards to radius of the ends. I took everything to my machinist, and he said that because his lathe bit was on the dull side.... from cutting flywheels.... that he could only get them within .008 or .010 from the adjustable pushrod I gave him. MY QUESTION.... What is acceptable tolerance....or margin for error.... before the geometry starts getting affected. I took these to a couple other machine shops, who said they could get it within .005 . This is crazy making. Mike No one....Eh??? mike have you posted ? on jakes site? i'll be doing this soon on my 2056. the chromoly came as a set of 8, right? keep us posted (IMG:style_emoticons/default/poke.gif) mike |
|
|
|
| Jake Raby |
Aug 9 2007, 12:20 AM
Post
#4
|
|
Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
+/- .001
If you don't use insane accuracy there is no reason to do the geometry process at all.. Remember that any pushrod length variation will be multiplied by the rocker arm ratio, so that .005 will net you .008 or so of a variance and that can lose you .020 valve lift or compromise the geometry completely. |
|
|
|
| Joe Ricard |
Aug 9 2007, 11:40 AM
Post
#5
|
|
CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
Just a clarification question on your kits Jake. Do the push rods come cut or do we have to do this step ourselves.
|
|
|
|
| mike373 |
Aug 9 2007, 05:15 PM
Post
#6
|
|
Member Group: Members Posts: 198 Joined: 3-August 05 From: san diego, ca Member No.: 4,536 |
Found a great machinist in Santee, Ca. He will get the pushrods within .001 . Yipee!
Ballistic Machine and Fabrication 619-562-8750 if anyone is interested. Mike |
|
|
|
| davep |
Aug 9 2007, 06:33 PM
Post
#7
|
|
914 Historian Group: Benefactors Posts: 5,143 Joined: 13-October 03 From: Burford, ON, N0E 1A0 Member No.: 1,244 Region Association: Canada  |
Just a dumb question here, since I have yet to order a kit, do the ball ends all measure the exact same so that when installed into the newly cut tubes the finished pushrods will all be the same length, or do you have to carefully measure them also to ensure the tubes are not cut too short.
Being anal, I'd assume the latter, and err on the long side, fit the end, measure total length, and adjust as necessary to get a perfect length on each one. |
|
|
|
| G e o r g e |
Aug 9 2007, 06:35 PM
Post
#8
|
|
Dr Group: Members Posts: 1,905 Joined: 20-September 05 From: Southern Cal Member No.: 4,832 Region Association: None 
|
QUOTE(Joe Ricard @ Aug 9 2007, 10:40 AM) Just a clarification question on your kits Jake. Do the push rods come cut or do we have to do this step ourselves. Joe, you cut them yourself (IMG:style_emoticons/default/sawzall-smiley.gif) |
|
|
|
| Joe Ricard |
Aug 10 2007, 10:31 AM
Post
#9
|
|
CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
Damn it.
Something to not look forward to when I order a kit. Maybe I should get better tools. Yea that's it get more and better tools. Brilliant!!!!!!! |
|
|
|
| Borderline |
Aug 10 2007, 10:57 AM
Post
#10
|
|
Senior Member Group: Members Posts: 720 Joined: 8-February 05 From: San Juan Bautista, CA Member No.: 3,577 Region Association: Northern California |
I don't know if I understand what you're doing. You set up one valve/pushrod and are now going to have all 8 pushrods machined to that length? I did each one individually on mine. They aren't all the same! especially if you're trying to get within .001"
|
|
|
|
| orange914 |
Aug 10 2007, 03:42 PM
Post
#11
|
|
http://5starmediaworks.com/index.html Group: Members Posts: 3,371 Joined: 26-March 05 From: Ceres, California Member No.: 3,818 Region Association: Northern California |
QUOTE(Borderline @ Aug 10 2007, 09:57 AM) I don't know if I understand what you're doing. You set up one valve/pushrod and are now going to have all 8 pushrods machined to that length? I did each one individually on mine. They aren't all the same! especially if you're trying to get within .001" i'll be doing this shortly also. the feed back i've got from various experianced builders is this: you can do each and every one BUT if you arent PRECISE to each (and you probably wont be) i've been told it's good to do just (1) exhaust and (1) intake. from there have exhaust and intakes done as sets. the basic idea is to adjust geometry to new cam base/lift. unless you really are anal on each one you could go backwards. feedback? (IMG:style_emoticons/default/confused24.gif) mike |
|
|
|
| JPB |
Aug 10 2007, 08:00 PM
Post
#12
|
|
The Crimson Rocket smiles in your general direction. Group: Members Posts: 2,927 Joined: 12-November 05 From: Tapmahamock, Va. Member No.: 5,107 |
There are afew steps to be taken and all tubes are custome cut to length. I think Jake has the info you need to do the job correctly and it might take a tool also. He has mentioned this in his Fourth Dimension shows. (IMG:style_emoticons/default/beer.gif)
|
|
|
|
|
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:
|
Lo-Fi Version | Time is now: 18th May 2024 - 06:14 AM |
Invision Power Board
v9.1.4 © 2024 IPS, Inc.