measure valve lift at retainer - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 05-25-2008, 09:48 AM
GMR GMR is offline
Registered User
 
Last photo:
Join Date: Sep 2006
Location: florida
Posts: 290
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
measure valve lift at retainer

I'm measuring for pushrod length and have a dial indicator set up on the valve spring retainer. I'm using a solid lifter, adjustable pushrod, Proform full roller rockers, the real valve springs I will be using.

When doing the pushrod length checking the most valve lift I'm seeing is .448 and that's with a pushrod that's way too long. I've tried 3 different rocker arms from the package and got .444, .446, .448.

When using a pushrod length closer to what I'll need (roller rocker tip pattern located in middle of valve tip), I'm getting only about .439 lift.

Cam card states .311 lobe lift (.467 with 1.5 rocker). I've previously checked this by placing the dial indicator on the edge of the lifter and it's ok (.311).

I'm thinking I'm not placing the dial indicator properly on the retainer.

Is this lower lift I'm seeing to be expected or do I have a problem?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 05-25-2008, 10:13 AM
68NovaSS's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Working with chromed bolts
Last journal entry: New to me T-Bucket
Last photo:
Join Date: Sep 2002
Location: Nine Mile Falls/Suncrest, WA
Posts: 5,285
Wiki Edits: 9

Thanks: 113
Thanked 139 Times in 130 Posts
I don't understand why you have a dial indicator on the spring, but the lift measured there should match what you see at the lifter, with solid lifters. It sounds like your pushrod maybe flexing/bending slightly? Regardless, I'd do the checking with lightweight checking springs, or remove the inner damper spring.
__________________
Boost adds dignity to what would otherwise be a vulgar brawl...

Midnight Sun Street Rod Association
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 05-25-2008, 11:09 AM
Registered User
 
Join Date: Mar 2007
Location: Iowa
Posts: 134
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Pushrod lenghth should have no affect whatsoever on the lift at the valve, except on extreme examples where pushrod flex is a problem.

What I would suspect is that your rocker ratio is not exactly 1.5, woldn't be unusual at all, especially with "off-brand" rockers. Rocker flex is also a possiblity if your springs are really heavy.

Set up a test stand to check your rockers with very little spring pressure, I'll bet the ratio is actually closer to 1.44 as indicated by your measurements.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 05-25-2008, 04:04 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 13,321
Wiki Edits: 326

Thanks: 839
Thanked 1,153 Times in 952 Posts
Quote:
Originally Posted by tdkkart
Pushrod lenghth should have no affect whatsoever on the lift at the valve, except on extreme examples where pushrod flex is a problem.

What I would suspect is that your rocker ratio is not exactly 1.5, woldn't be unusual at all, especially with "off-brand" rockers. Rocker flex is also a possiblity if your springs are really heavy.

Set up a test stand to check your rockers with very little spring pressure, I'll bet the ratio is actually closer to 1.44 as indicated by your measurements.
Bingo, we have the correct answer
I've known guys to make friends with the parts counterman at the local Chevy dealer so they could take a set of rockers home, check the ratio and return for another load of rockers until they find the highest ratio for a complete set.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 05-25-2008, 08:08 PM
Stroke Meister
 
Last photo:
Join Date: Mar 2007
Location: MI, USA
Posts: 703
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
There is more to this along with what has been stated already. IMO, subtle changes in VT geometry will cause the things you are seeing here. Not always will max lift occur when the pattern is centered, nor will a centered pattern be the absolute correct geometry. Flex in the valvetrain components along with tolerance stacking play into this deal, as well as parts used. Checking springs do not load the components as do actual springs and their pressures and will net a different number, most always. I have tons of data in regards to this matter, and have sought to compile data for different rocker mfrs, as well as map (graph) lift at the retainer in 5* increments for 720* crank rotation for each, with up to three different pushrod lengths as well as varying valve lengths . They all net different results and give much to look at. On the geometry end of it, things are not as simple as most believe, and the only way to see these things is to actually check. Seeing is believing (read - actual measurements). My PC suffered a major meltdown though, and all the data from my notes etc. are still in that PC. I could redo all of the noted material, but that took a looong time to enter and all of that, and I've not had the chance to recover the entered data from the toasted PC, but I'll get to it - looks like in my extra spare time. This topic is a good source for debate and is much like the 'more than one way to skin a cat' deal. That being said, you may never see the advertised lift for your app, and if you do, I'd hazard a guess your geometry is wabi sabi, or, imperfect, impermanent, and incomplete. JMO
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 05-25-2008, 08:18 PM
GMR GMR is offline
Registered User
 
Last photo:
Join Date: Sep 2006
Location: florida
Posts: 290
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks for the responses fellas.

I hope the pushrod isn't flexing. The spring is 115 lbs seat and 300 lbs open and the pushrod is Trickflow 5/16 chromemoly .080 thickness. I get identical results with the adjustable pushrod as I do with the Trickflow one piece unit.
But if you still think I should change the springs I'll try it.

I'm missing how I'm going to check the rocker arm ratio. I kind of thought I was doing that with the dial indicator on the retainer. Is there an easier/better way?
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 05-25-2008, 09:25 PM
carsavvycook's Avatar
My 2 cents worth
 
Last photo:
Join Date: Sep 2007
Location: Lakeside, CA
Age: 58
Posts: 2,855
Wiki Edits: 3

Thanks: 2
Thanked 2 Times in 2 Posts
I would say you are checking it real close to as accurate as you can get. Your problem is most likely the Proform rockers. I understand they are made in China and would not be surprised if they are junk.

Last edited by carsavvycook; 05-25-2008 at 09:26 PM. Reason: word correction
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 05-25-2008, 09:30 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 13,321
Wiki Edits: 326

Thanks: 839
Thanked 1,153 Times in 952 Posts
Stroke, I see you have zero wiki edits. When you recover the information, you could do us all a good turn by posting it on the wiki for all to see When a certain question keeps coming up, I research what I don't know about it, then compile it into a (hopefully) comprehensive, intelligent format and post it on the wiki. The thread titled "intake manifold gasket" that can currently be viewed on the engine board is a good example. I read the poster's problem, went to the wiki and copied the URL to an article I had posted earlier, then went back to the thread and pasted the link. Quick, easy and correct.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 05-26-2008, 07:41 AM
Stroke Meister
 
Last photo:
Join Date: Mar 2007
Location: MI, USA
Posts: 703
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Good call techinspector1. I decided to look into that stuff originally because of arguments etc. Let me say this, until I did the data/measuring etc, I thought things were good to go the way I'd done it for years. However, upon digging into things a bit deeper, comparing, measuring and so forth, I have a little different view of this than before. I spent a whole lot of time doing this stuff, looking at over arcing under arcing comparing max lift and geometry etc etc etc. Some have said it's a waste of time, but having gone through the trouble, I hardly find it a waste of time. Like I said, seeing is believing. When I toasted the old PC with about 25+GB of stuff on it I was quite disturbed. Going through everything is going to take a bit but I know it won't be as tedious as when I did it the first time. It's just a matter of slaving that HDD, learning this new OS and it's 'ways' along with the time thing. Your Wiki suggestion is a good one, who'da thunk?
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 05-26-2008, 09:13 AM
GMR GMR is offline
Registered User
 
Last photo:
Join Date: Sep 2006
Location: florida
Posts: 290
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Seems you fellas are pretty much in agreement I made a mistake with the Proform rockers. They were recommended to me by the tech at Competition Products.

Anyway, good information, very helpful, thankyou.

Stroke, I might take a shot at graphing the lift vs. crank degrees and then combine those results with the pattern/witness mark I see at the valve tip to determine pushrod length. Sounds like fun. Any particular reason you chose to use an increment of crank degrees and then write down the lift, instead of an increment of lift and then write down the crank degrees?

I know the results will be the same but wondering if looking at it from the different perspectives presented by the two methods - if one makes it easier to interpret the results. Just wondering why you chose one method over the other.

Last edited by GMR; 05-26-2008 at 09:27 AM.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may 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
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
master cylinder interchange runn141 Suspension - Brakes - Steering 7 05-03-2009 06:15 AM
Valve Springs Lift juiced66malibu Engine 2 03-08-2008 12:54 PM
how to properly measure the lift of a cam ? NOW WITH A MULTIPLE CHOICE POLL!!! lowROLLERchevy Engine 6 10-02-2007 08:30 AM
valve spring lift stfinney Engine 1 10-30-2002 06:14 AM
Max valve lift (chevy) americanfreedoms Engine 3 06-24-2002 01:02 PM


All times are GMT -6. The time now is 11:49 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.