Checking pushrod length - pattern too wide? - 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 05-06-2012, 09:13 PM
Registered User
 
Last photo:
Join Date: Dec 2010
Location: New Mexico
Posts: 50
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Checking pushrod length - pattern too wide?

Hello all. I'm setting up my motown heads for a 232/240 @ .050, 525/543 lift 110 lsa small base solid street roller cam in my sbc. I'm using comp 930 springs (153 @ 1.9 - actually looks like about 140-145 lbs actually seated) with lightweight tool steel 10 deg retainers, rev-kit, and summit 1.5 full roller rockers. Valves are Manley race master 2.08 int and 1.6 exh with cast iron guides and viton seals. Pushrods are engine pro 6.5" 5/16X.083.

Anyway, I'm checking for pushrod length (with about .015 lash) and i'm getting a center pattern but is is a wide sweep - more like 3/32-18" wide pattern with about 3.32+ away from the end of the valve stem. Is this too wide a pattern or am I concerned over nothing. I'm looking for a narrow pattern (more like .060-.080 max) but I'm not getting it. Any opinions or experiences appreciated. Thanks.
Attached Thumbnails
Click image for larger version

Name:	rocker_tip_pattern.JPG
Views:	109
Size:	87.3 KB
ID:	65224  

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 05-07-2012, 12:59 AM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 597 Times in 546 Posts
Quote:
Originally Posted by leverhead
Hello all. I'm setting up my motown heads for a 232/240 @ .050, 525/543 lift 110 lsa small base solid street roller cam in my sbc. I'm using comp 930 springs (153 @ 1.9 - actually looks like about 140-145 lbs actually seated) with lightweight tool steel 10 deg retainers, rev-kit, and summit 1.5 full roller rockers. Valves are Manley race master 2.08 int and 1.6 exh with cast iron guides and viton seals. Pushrods are engine pro 6.5" 5/16X.083.

Anyway, I'm checking for pushrod length (with about .015 lash) and i'm getting a center pattern but is is a wide sweep - more like 3/32-18" wide pattern with about 3.32+ away from the end of the valve stem. Is this too wide a pattern or am I concerned over nothing. I'm looking for a narrow pattern (more like .060-.080 max) but I'm not getting it. Any opinions or experiences appreciated. Thanks.
Use an adjustable pushrod to try different lengths. Brief instructions for making an adjustable pushrod length checking tool are here. Also there is another link (post #3) to a short Crankshaft Coalition article on valve train geometry.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 05-07-2012, 07:52 AM
Registered User
 
Last photo:
Join Date: Dec 2010
Location: New Mexico
Posts: 50
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Thanks for the reply. I also tried a slightly longer pushrod and the contact pattern is narrower but towards the exhaust side of the valve stem. So I'm trying to figure if it is better to have the wider pattern in the center or narrower pattern towards the outside. It seems the rocker needs to be higher up on the stud for the ideal pattern but the more I move the rocker 'up' on the stud the closer the roller tip is to the outside of the valve, so I'm wondering if I have the wrong rocker (too long?). I believe the center of axis on the trunnion to the center of the roller tip is about 2 1/4".
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 05-07-2012, 08:06 AM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 597 Times in 546 Posts
Quote:
Originally Posted by leverhead
Thanks for the reply. I also tried a slightly longer pushrod and the contact pattern is narrower but towards the exhaust side of the valve stem. So I'm trying to figure if it is better to have the wider pattern in the center or narrower pattern towards the outside. It seems the rocker needs to be higher up on the stud for the ideal pattern but the more I move the rocker 'up' on the stud the closer the roller tip is to the outside of the valve, so I'm wondering if I have the wrong rocker (too long?). I believe the center of axis on the trunnion to the center of the roller tip is about 2 1/4".
The general concensus is narrow is better than centered. Maybe someone else will chime in.

I'll give you a couple more links for you to take a look at in the meantime:

Mid-lift rocker theory HERE.

THREAD on geometry.

There have been many threads on this, you can use the google custom search engine at the top of the page for more on the subject.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 05-07-2012, 08:45 AM
Registered User
 
Last photo:
Join Date: Dec 2010
Location: New Mexico
Posts: 50
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Thanks. I've googled the heck out of it and get the same conflicting opinions...some say narrow-anywhere, some say centered, others say as long as the roller tip stays on the valve. I guess there will have to be some compromise at some point.

I guess if I use the mid-lift theory I would use the shorter pushrod as this starts the tip on the intake side of center then rollers over to the exhaust side at max lift....just the pattern is wider...like 1/8".
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 05-07-2012, 08:54 AM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 597 Times in 546 Posts
Ideally centered and narrowest. But as you've suspected, different rockers- even rockers having the same ratio- can also give you a different pattern. It's just that most of us cannot justify buying three or more different sets of rockers looking for the one "best" set.

But if you're stuck w/one set of rockers, my best advice is still to use a checking p-rod and use whatever length that gets you the narrowest pattern, regardless of the location on the valve tip unless the rocker is rolling off the tip itself.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 05-07-2012, 09:09 AM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 8,876
Wiki Edits: 0

Thanks: 17
Thanked 307 Times in 287 Posts
Quote:
Originally Posted by leverhead
Thanks. I've googled the heck out of it and get the same conflicting opinions...some say narrow-anywhere, some say centered, others say as long as the roller tip stays on the valve. I guess there will have to be some compromise at some point.

I guess if I use the mid-lift theory I would use the shorter pushrod as this starts the tip on the intake side of center then rollers over to the exhaust side at max lift....just the pattern is wider...like 1/8".
NARROWER is better unless your roller is going off the edge. Centered is ideal but it would require different rockers or moving the stud location, but you need a narrow pattern first and foremost.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 05-07-2012, 09:10 AM
Registered User
 
Last photo:
Join Date: Dec 2010
Location: New Mexico
Posts: 50
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Thanks. Like you said, I cant keep buying new parts just to 'test' them so at some point I'll have to compromise. The rockers I have are like new with no miles on them so I'd like to make them work. I've tried the adjustable rod and it looks like the longer rod will give me the narrowest pattern (about .080)even if it is off center.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 05-07-2012, 12:28 PM
Registered User
 
Last photo:
Join Date: Apr 2007
Location: Seattle, Wa
Posts: 6,750
Wiki Edits: 0

Thanks: 4
Thanked 417 Times in 360 Posts
Quote:
Originally Posted by leverhead
Hello all. I'm setting up my motown heads for a 232/240 @ .050, 525/543 lift 110 lsa small base solid street roller cam in my sbc. I'm using comp 930 springs (153 @ 1.9 - actually looks like about 140-145 lbs actually seated) with lightweight tool steel 10 deg retainers, rev-kit, and summit 1.5 full roller rockers. Valves are Manley race master 2.08 int and 1.6 exh with cast iron guides and viton seals. Pushrods are engine pro 6.5" 5/16X.083.

Anyway, I'm checking for pushrod length (with about .015 lash) and i'm getting a center pattern but is is a wide sweep - more like 3/32-18" wide pattern with about 3.32+ away from the end of the valve stem. Is this too wide a pattern or am I concerned over nothing. I'm looking for a narrow pattern (more like .060-.080 max) but I'm not getting it. Any opinions or experiences appreciated. Thanks.
Depends on what the purpose of the engine is. The wider pattern in the center minimizes side load on the stem which is best for maximum stem and guide life but it compromises max lift about .005 inch. A tight pattern off to the side introduces some higher side loads onto the stem which increases the wear rate between stem and guide, but this optimizes the lift.

If you need lots of miles between rebuilds the wide centered pattern is the one to use. If you need every last pony the engine can possibly make then the narrow off center pattern is the one to use.

Bogie
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 05-07-2012, 01:34 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 8,876
Wiki Edits: 0

Thanks: 17
Thanked 307 Times in 287 Posts
Quote:
Originally Posted by oldbogie
Depends on what the purpose of the engine is. The wider pattern in the center minimizes side load on the stem which is best for maximum stem and guide life but it compromises max lift about .005 inch. A tight pattern off to the side introduces some higher side loads onto the stem which increases the wear rate between stem and guide, but this optimizes the lift.

If you need lots of miles between rebuilds the wide centered pattern is the one to use. If you need every last pony the engine can possibly make then the narrow off center pattern is the one to use.

Bogie

How does the centered wide pattern produce LESS side loading? It has much more force perpendicular to the valve stem. For wear reasons alone I choose the narrow pattern, the extra lift is just an added bonus.

I see the argument for a centered contact point, but wouldn't minimal scrub be more imporant for wear? Centered with minimal scrub is best of course, bu most people (including myself) don't want to get into moving the rocker stud.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 05-07-2012, 03:28 PM
dave171's Avatar
Registered User
 
Join Date: Sep 2006
Location: Alabama
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I was having the same problem and some one told me my studs may have been flexing. I put my stud girdle on and rechecked it and it helped a lot.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 05-07-2012, 06:28 PM
Registered User
 
Last photo:
Join Date: Dec 2010
Location: New Mexico
Posts: 50
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
For what its worth here are a couple more pics...... the wider pattern in the center (shorter pushrod) and the narrow pattern closer to the exhaust side (longer push rod). I tried the mid lift technique but lining it up that way puts the tip of the roller on the outside (exhaust side) almost at the edge of the valve stem.

I set up a dial indicator and measured the lift (at zero lash) with both pushrods and after a couple attempts each way found that the longer pushrod gave me .005 - .010 more lift. Obviously I can't verify anything when it comes to the loading on the valve/guides either way.

Next I'll check into the rockers....I may try the comp pro magnum rollers (self aligning) as the rollers I have been testing with (1.5) have no markings whatsoever other than the ratio and barely clear the retainers. I may try to up the ratio to regain the lift I am losing with the valve lash.
Attached Thumbnails
Click image for larger version

Name:	rocker_tip2.JPG
Views:	91
Size:	95.1 KB
ID:	65288   Click image for larger version

Name:	rocker_tip3.JPG
Views:	107
Size:	95.5 KB
ID:	65289  
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 05-07-2012, 09:33 PM
dave171's Avatar
Registered User
 
Join Date: Sep 2006
Location: Alabama
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I don't know if this will help but it's worth a try. http://www.compcams.com/Pages/417/va...-geometry.aspx
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 05-08-2012, 06:24 AM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 8,876
Wiki Edits: 0

Thanks: 17
Thanked 307 Times in 287 Posts
Quote:
Originally Posted by dave171
I don't know if this will help but it's worth a try. http://www.compcams.com/Pages/417/va...-geometry.aspx
the diagram the supply is wrong if you're looking for minimal scrub.
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:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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
Confused on checking pushrod length Silver Surfer Hotrodding Basics 1 05-04-2012 09:33 AM
Checking pushrod length with checking springs? v8hed Engine 1 01-22-2011 06:20 PM
checking pushrod length w/ hyd. lifters awoodman Engine 9 11-05-2007 05:42 AM
Pushrod length? Trav Engine 2 10-07-2003 10:50 PM
@@@Pushrod Length@@@ lakecityg Engine 1 06-21-2003 07:50 AM


All times are GMT -6. The time now is 04:12 AM.


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.