Moparchat - Home of MOPAR enthusiasts worldwide!



Go Back   Moparchat - Home of MOPAR enthusiasts worldwide! > Technical Forums > Performance Talk

Click here to search for Mopar cars and parts for sale.


Reply
 
Thread Tools Display Modes
  #1  
Old 08-14-2007, 06:41 PM
Dukes2fast Dukes2fast is offline
Inactive User
 
Join Date: May 2005
Location: Burke, NY
Age: 57
Posts: 233
Default Valve stem tip height

I got my heads back from the shop and I noticed that the valve stem tips are not all exactly the same height. I laid a straight edge across the valve stem tips and found there was quiet a bit of variance. Won't this effect pre-load etc..? I have non-adjustable rockers. What is the fix? can the tips be ground down to the same height? How much variance is tolerable?
Reply With Quote
  #2  
Old 08-14-2007, 08:04 PM
dwc43's Avatar
dwc43 dwc43 is offline
Banned
 
Join Date: Sep 2002
Location: Shelbyville,Tn.
Age: 54
Posts: 23,987
Biggrin

IT will effect pre load, the tips can't be ground that much cause they are only hardened so deep into the stem. Did you install new valves or seats? Most likely the reason. If hte seats have been ground on a lot or the valves have been ground on then that causes them to sit deeper than some and it changes the stem height. New valves and seats will cure it for sure.
Reply With Quote
  #3  
Old 08-14-2007, 10:34 PM
wilks3 wilks3 is offline
Inactive User
 
Join Date: Sep 2006
Location: Nashville,Illinois
Posts: 385
Default

I've never used them,but would valve stem lash caps on the short ones fix the problem? How much difference is there? You might have to take back to machine shop and have them fixed.
Reply With Quote
  #4  
Old 08-14-2007, 10:47 PM
dwc43's Avatar
dwc43 dwc43 is offline
Banned
 
Join Date: Sep 2002
Location: Shelbyville,Tn.
Age: 54
Posts: 23,987
Biggrin

You could use lash caps, but that's a cruch. Better to take it back and fix it the right way.
Reply With Quote
  #5  
Old 08-15-2007, 03:39 AM
DartGT66 DartGT66 is offline
Inactive User
 
Join Date: Sep 1999
Location: vantaa,finland
Posts: 4,622
Default

If your valves are the same length, it means that in some chambers the valves have been ground deeper than in the others. This will also affect piston to valve vlearances, chamber sizes etc, and grinding valves deep will also usually make the heads flow worse.
Reply With Quote
  #6  
Old 08-15-2007, 11:39 AM
ehostler's Avatar
ehostler ehostler is offline
Registered User
 
Join Date: Jan 2000
Location: Annandale, VA
Age: 57
Posts: 15,212
Default

The machine shop messed them up. Have the machine shop make them right.
Reply With Quote
  #7  
Old 08-15-2007, 12:00 PM
sanborn sanborn is offline
Inactive User
 
Join Date: May 1999
Location: shelbyville,tn,USA
Posts: 2,880
Default

In defense of the machine shop---they usually only grind the seats enough to clean them up. If you want to "equalize the seat depth", that usually requires more $$$. And that should be discussed before the work begins.
Reply With Quote
  #8  
Old 08-15-2007, 01:23 PM
turbododge turbododge is offline
Inactive User
 
Join Date: Feb 2000
Location: Minnesota,USA
Posts: 1,198
Default

Like Sanborn said, the seat work for a standard valve job does not equalize the depth. You will also find they sometimes use replacement valves that aren't exactly the same length or have some that have been ground and some not.

Just went through the same thing myself with over .010 difference in height. Since I needed to shim the shaft anyway, I had them shorten the long ones to match the shortest and then shimmed the shaft to get good contact patch.

Be sure to do all the shimming and contact patch work before you check your pushrod length.
Reply With Quote
  #9  
Old 08-16-2007, 08:40 PM
The_Dakota_Kid The_Dakota_Kid is offline
Inactive User
 
Join Date: Aug 2006
Location: Inside my engine
Posts: 57
Default

How much are we talking about here? Lash caps will work fine, just make sure they dont touch or "lay" on the retainer, this would be bad.....if more than .050 you might have problems, with lifter pre-load,
Reply With Quote
  #10  
Old 08-17-2007, 06:37 AM
Dukes2fast Dukes2fast is offline
Inactive User
 
Join Date: May 2005
Location: Burke, NY
Age: 57
Posts: 233
Default

The worst one is almost .020 higher than the rest. The others are within few thounsanths of each other. I talked to the shop (I know the guy pretty good)and he said he is confident it won't be an issue with hydraulic lifters. I am going to check the preload tonight and see what the differences are there.
Reply With Quote
  #11  
Old 08-17-2007, 08:11 AM
DartGT66 DartGT66 is offline
Inactive User
 
Join Date: Sep 1999
Location: vantaa,finland
Posts: 4,622
Default

Out of the box mopar performance Stage VI's had .060" difference.
Reply With Quote
  #12  
Old 08-17-2007, 10:44 AM
Dukes2fast Dukes2fast is offline
Inactive User
 
Join Date: May 2005
Location: Burke, NY
Age: 57
Posts: 233
Default

Quote:
Originally Posted by DartGT66 View Post
Out of the box mopar performance Stage VI's had .060" difference.
What did you do to fix them?


I checked an old set of 906 heads I had lyning around and they are almost perfect, maybe .003-.005 difference.
Reply With Quote
  #13  
Old 08-17-2007, 04:27 PM
The_Dakota_Kid The_Dakota_Kid is offline
Inactive User
 
Join Date: Aug 2006
Location: Inside my engine
Posts: 57
Default

.020 isnt that bad, if this is a typical rebuild dont worry about it. what cam and lifters are you going to run, some of the Xtreme comp stuff requires very little preload, but they also suggest adjustable rocker gear.....

run it!
Reply With Quote
  #14  
Old 08-17-2007, 04:56 PM
turbododge turbododge is offline
Inactive User
 
Join Date: Feb 2000
Location: Minnesota,USA
Posts: 1,198
Default

You do need to check the contact pattern on the valve tip with the rocker. .020 is plenty enough to mess up the contact and shorten valve guide life, or even eat pushrods. The rebuilder books will give a tolerance of something like .030, but just because the lifter can handle it, doesn't make it a good idea.
Reply With Quote
  #15  
Old 08-18-2007, 06:53 PM
Dukes2fast Dukes2fast is offline
Inactive User
 
Join Date: May 2005
Location: Burke, NY
Age: 57
Posts: 233
Default

Quote:
Originally Posted by The_Dakota_Kid View Post
.020 isnt that bad, if this is a typical rebuild dont worry about it. what cam and lifters are you going to run, some of the Xtreme comp stuff requires very little preload, but they also suggest adjustable rocker gear.....

run it!
It is a MP .509 cam. I am replacing the lifters with new CompCam lifters.
Reply With Quote
  #16  
Old 08-21-2007, 10:48 PM
YellowDuster YellowDuster is offline
Inactive User
 
Join Date: Aug 2007
Location: Crowley, TX
Age: 56
Posts: 11
Default

I would try to get them closer than that! Trying to make up the diff. with lash caps doesn't work too well. I've tried that before and it's more trouble than it's worth.
Reply With Quote
  #17  
Old 08-22-2007, 09:59 PM
djswwg djswwg is offline
Inactive User
 
Join Date: Apr 2000
Location: in my garage
Posts: 1,401
Default

If the valves are all the same length the problem is with the seats or the area on the valve head that seats on the head. You could try grinding all the valves to match the shortest one and then use lash caps to get the height back. A lot depends on how much power you want to make. If it's a high output engine better fix it right and use lash caps for added valve tip life. If it's just gotta run pretty well then patching it as I suggested here will likely work just fine.......djs
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Valve stem size? Ray Bell Slant Six Chat 2 02-21-2008 07:18 AM
Valve stem hight 85shelbycharger Front Wheel Drive Chat 1 04-29-2006 01:30 AM
Valve Stem Oil Seals boboh1 Slant Six Chat 18 12-22-2005 07:40 PM
changing valve stem seals? Chache876 Performance Talk 5 09-05-2004 04:24 PM
I need some help with valve stem seals rallye72 Performance Talk 2 12-09-2003 02:35 PM




All times are GMT -4. The time now is 08:37 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
. . . . .