How can you be sure when a cam is failing? - 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 09-20-2009, 06:42 PM
Member
 
Last photo:
Join Date: Aug 2004
Location: Kentucky
Age: 41
Posts: 212
Wiki Edits: 0

Thanks: 8
Thanked 1 Time in 1 Post
How can you be sure when a cam is failing?

I'm sure most know the signs of a bad cam. The excess valve noise from the extra clearances, engine running rough, pushrods not turning, and so on. However I pulled a cam out of my 406 last year that had only one bad lobe. It had at least .050 material worn off, however you could never tell it from the lifter. All 16 lifters looked the same and appeared to be perfect. The engine didn't miss either and I didn't hear any ticking from the valvetrain. The cam had maybe 300 miles on it, it could have been in the infancy of it's failure.
All of this is leading up to my current cam. I have a XE284 cam in my 406 now and my engine has always had a miss since installing the cam. I've checked and replaced everything but the cam. I had the intake off a few months ago and I pulled each lifter out and looked at the bottoms. They all looked great. However that doesn't mean anything since they also looked good on my other cam. All of the pushrods spin when the engine is running. I can hear a very mild ticking, but it could have always been there or could be an exhaust leak. All of the rockers move up and down when the engine is running. However there could be a couple that aren't moving as much as the rest. You can't tell by eyeballing whether a lobe is worn down a little more than the rest.
I don't have a good enough dial indicator to measure my lift on the pushrods. It looks like I may need to pull the cam and measure each lobe. I had thought about pulling the intake and then try to view the cam lobes thru the lifter bores. thats not real accurate, but it may work. I didn't need to measure the lobes on the other cam to know they were bad. They stood out like a sore thumb. I guess with the intake off I could measure how far up each lifter raises.
Any help or advice would be appreciated.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 09-20-2009, 07:44 PM
S10 Racer's Avatar
http://www.warsprints.com
 

Last journal entry: W.A.R. (Wingless Auto Racing) Sprint Car Racing
Last photo:
Join Date: Nov 2007
Location: At The Dirt Tracks
Age: 55
Posts: 1,881
Wiki Edits: 0

Thanks: 3
Thanked 59 Times in 54 Posts
Quote:
Originally Posted by 4speed57
I'm sure most know the signs of a bad cam. The excess valve noise from the extra clearances, engine running rough, pushrods not turning, and so on. However I pulled a cam out of my 406 last year that had only one bad lobe. It had at least .050 material worn off, however you could never tell it from the lifter. All 16 lifters looked the same and appeared to be perfect. The engine didn't miss either and I didn't hear any ticking from the valvetrain. The cam had maybe 300 miles on it, it could have been in the infancy of it's failure.
All of this is leading up to my current cam. I have a XE284 cam in my 406 now and my engine has always had a miss since installing the cam. I've checked and replaced everything but the cam. I had the intake off a few months ago and I pulled each lifter out and looked at the bottoms. They all looked great. However that doesn't mean anything since they also looked good on my other cam. All of the pushrods spin when the engine is running. I can hear a very mild ticking, but it could have always been there or could be an exhaust leak. All of the rockers move up and down when the engine is running. However there could be a couple that aren't moving as much as the rest. You can't tell by eyeballing whether a lobe is worn down a little more than the rest.
I don't have a good enough dial indicator to measure my lift on the pushrods. It looks like I may need to pull the cam and measure each lobe. I had thought about pulling the intake and then try to view the cam lobes thru the lifter bores. thats not real accurate, but it may work. I didn't need to measure the lobes on the other cam to know they were bad. They stood out like a sore thumb. I guess with the intake off I could measure how far up each lifter raises.
Any help or advice would be appreciated.
I had the same issue on a BBC with a solid FT cam. It would miss a little until I adjusted the valves and it would be fine for a couple runs (drag strip only). I finally broke a pushrod and was forced to rebuild the motor. That's when I found the cam had 1 lobe wiped but it also affected the lifter. You have covered all the tell-tale signs I know of for diagnosing without pulling the cam out. Are you running a good oil with high zinc content?
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 09-20-2009, 07:46 PM
Registered User
 
Last photo:
Join Date: Aug 2008
Location: Nova Scotia, Canada
Posts: 337
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
I wish I had a definite answer because I've wondered the same thing myself.

However, I suspect cam lobe surfaces are case hardened, or some sort of surface treatment that isn't very thick. So once you go through that, rapid wear subsequently begins. I'd say you caught that first cam during a very tight window between intial failure and catastrophic failure. In other words, it woldn't have taken much longer before a genuine missfire situation would have occured.

Better to use a dial indicator on the lifter shell than the pushrod with hyd lifters, but as you dont' have one, do you have a good digital vernier caliper? (You can get a decent one on sale for about $20.) If so, remove the intake manifold and measure the amount of lifter above the hole in the block at max lift and again at min lift, and then compare it to some others. Use the depth guage part of th calipers for this.

As far as your miss goes, double check your valve adj and also seriously look at your ignition system. You can start with the sparkplugs, but plug wires can go bad quickly, so the midnight look-for-spark-leakage is a good idea.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 09-20-2009, 07:57 PM
NEW INTERIORS's Avatar
Believe in yourself !!!!!!
 

Last journal entry: 41 WILLYS FRAME
Last photo:
Join Date: Jul 2007
Location: In My Shop..
Age: 49
Posts: 10,071
Wiki Edits: 0

Thanks: 1,226
Thanked 541 Times in 401 Posts
Popping out the exhaust or the carb is a good sign most of the time..
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 09-20-2009, 08:33 PM
Member
 
Last photo:
Join Date: Aug 2004
Location: Kentucky
Age: 41
Posts: 212
Wiki Edits: 0

Thanks: 8
Thanked 1 Time in 1 Post
Thanks for the replies. I've been using good quality motor oil And changing it frequently. I do have some calipers and I was thinking of trying the method you suggest Argess. It should give me an indication if anything is wrong.
I haven't noticed a pop out of the exhaust or carb yet. Would the cam have to be eroded pretty bad to produce a backfire?
I'll go back over everything one more time before I start tearing into it.

Thanks so much for your help guys.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 09-20-2009, 08:38 PM
NEW INTERIORS's Avatar
Believe in yourself !!!!!!
 

Last journal entry: 41 WILLYS FRAME
Last photo:
Join Date: Jul 2007
Location: In My Shop..
Age: 49
Posts: 10,071
Wiki Edits: 0

Thanks: 1,226
Thanked 541 Times in 401 Posts
I would try resetting the valves...
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 09-21-2009, 12:12 AM
Member
 
Last photo:
Join Date: Aug 2004
Location: Kentucky
Age: 41
Posts: 212
Wiki Edits: 0

Thanks: 8
Thanked 1 Time in 1 Post
I have an update.

I found the old lifters in my garage that went with my last cam that failed. I cleaned all the lifters really well and I found one that looked like it was sandblasted on the bottom. It didn't have the machined smooth, shiny surface. I'm sure it was the lifter that went with the bad lobe.
I also went out tonight and marked my pushrods again so I could see if they were spinning. I cranked the engine over a few times and it looks like the pushrods on cylinders 7 and 8 are barely turning. Both of them being the exhaust valves. All the other pushrods spun several times while these didn't. Last week I was pulling the plug wires off one at a time trying to pinpoint the miss. I noticed cylinders 7 and 8 didn't seem to pull the engine down when the plug wires were removed.
I'm going ahead and pulling the intake tomorrow and look at the bottom of the lifters. I'll also measure the lift of the lifters in the bores.
I've had my intake off so many times, I could do it in my sleep!

Thanks again for the replies.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 09-21-2009, 02:50 AM
S10 Racer's Avatar
http://www.warsprints.com
 

Last journal entry: W.A.R. (Wingless Auto Racing) Sprint Car Racing
Last photo:
Join Date: Nov 2007
Location: At The Dirt Tracks
Age: 55
Posts: 1,881
Wiki Edits: 0

Thanks: 3
Thanked 59 Times in 54 Posts
Quote:
Originally Posted by 4speed57
I have an update.

I found the old lifters in my garage that went with my last cam that failed. I cleaned all the lifters really well and I found one that looked like it was sandblasted on the bottom. It didn't have the machined smooth, shiny surface. I'm sure it was the lifter that went with the bad lobe.
I also went out tonight and marked my pushrods again so I could see if they were spinning. I cranked the engine over a few times and it looks like the pushrods on cylinders 7 and 8 are barely turning. Both of them being the exhaust valves. All the other pushrods spun several times while these didn't. Last week I was pulling the plug wires off one at a time trying to pinpoint the miss. I noticed cylinders 7 and 8 didn't seem to pull the engine down when the plug wires were removed.
I'm going ahead and pulling the intake tomorrow and look at the bottom of the lifters. I'll also measure the lift of the lifters in the bores.
I've had my intake off so many times, I could do it in my sleep!

Thanks again for the replies.
Are you running a hyd. or solid cam?
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 09-21-2009, 08:26 AM
Registered User
 
Last photo:
Join Date: Apr 2008
Location: wisconsin
Posts: 174
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
i had a miss since i put my motor together finally looked at the header bolts some were about to fall out tightened them up and it was gone sounded just like a lifter, i adjusted my lifters like 5 times for nothing put more oil in and then checked my plugs and wires and distrubitor and stuff wasted lots of time
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 09-22-2009, 03:12 AM
Member
 
Last photo:
Join Date: Aug 2004
Location: Kentucky
Age: 41
Posts: 212
Wiki Edits: 0

Thanks: 8
Thanked 1 Time in 1 Post
Well I pulled my intake off tonight and I got to the lifters. It appears my cam is toast. I had several lifters that didn't look very good on the bottom. I'm going to try and measure the lift from of each lifter. I'm sure that is a waste of time since it's obvious the cam is going flat.

Thanks for your time
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
Cam tight on insertion 70bird Engine 12 12-27-2008 07:51 PM
good cam? boatanchors Engine 6 11-19-2008 08:31 PM
roller cam selection for my monte ss redbandit98 Engine 37 06-21-2008 10:39 AM
Cam button length/clearance..? mrdreex Engine 1 04-12-2008 10:17 PM
Help Me Pick A Cam Canadian Charlie Engine 2 11-16-2005 01:11 PM


All times are GMT -6. The time now is 08:28 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.