Cam and valve stem tip pitting (long)
Thread Starter
Drifting
Joined: Sep 1999
Posts: 1,411
Likes: 1
From: Wylie TX
Cam and valve stem tip pitting (long)
Well, I pulled my motor apart to attempt to find the oil consumption problem and do a budget rebuild.
Here is what I did not expect to find (warning large pics):
Wiped cam lobe pic #1
Wiped cam lobe pic #2
Pitted valve #1
Pitted valve #2 (different valve)
The cam is a Comp Cams Xtreme Energy solid roller with their Endure-X roller lifters. The springs are Manley with 160/440 closed/open pressures. The rocker arms are 1.55 ratio Comp Pro Magnum full roller giving about .565"/.580" lift.
The cam/lifters have 30k miles on them and the lifters were fine at 20k miles, the last time I pulled the intake. The lash was adjusted 1k prior to the pull and were not out of adjustment at that time. Like an idiot, I didn't check the lash when I pulled the motor.
The biggest suprise about the cam is that the lifter wheel is still tight and spins just like new. There is some wear on the face of the wheel (forgot to get a pic of it), but for the most part it is fine. I really don't understand how the cam could have failed before the lifter. I'm also assuming that the pitting is from the trash metal that wore off of the lobe.
It does look like the lifter was riding towards the rear part of the lobe, but cam was limited to .006" - .008" of endplay with a roller cam button.
On to the valves. 6 of the exhaust valves have some pitting. None of the intake valves have any pitting. I'm really worried because it looks like the rocker arms were not centered (left to right) on the valve tip. I'm not sure how this could happen or how to fix it, especially since the intake valves all look fine.
Anything I'm missing about exhaust valves that would explain how the intake valves are all fine? Again, the only explanation I can think of for the pitting is some trash metal getting under the roller wheel of the rocker and pitting it.
Anybody have any ideas as to what could have caused either of these?
I'll also be sending Comp Cams an email to see what they have to say, but I don't really expect a reply.
Here is what I did not expect to find (warning large pics):
Wiped cam lobe pic #1
Wiped cam lobe pic #2
Pitted valve #1
Pitted valve #2 (different valve)
The cam is a Comp Cams Xtreme Energy solid roller with their Endure-X roller lifters. The springs are Manley with 160/440 closed/open pressures. The rocker arms are 1.55 ratio Comp Pro Magnum full roller giving about .565"/.580" lift.
The cam/lifters have 30k miles on them and the lifters were fine at 20k miles, the last time I pulled the intake. The lash was adjusted 1k prior to the pull and were not out of adjustment at that time. Like an idiot, I didn't check the lash when I pulled the motor.
The biggest suprise about the cam is that the lifter wheel is still tight and spins just like new. There is some wear on the face of the wheel (forgot to get a pic of it), but for the most part it is fine. I really don't understand how the cam could have failed before the lifter. I'm also assuming that the pitting is from the trash metal that wore off of the lobe.
It does look like the lifter was riding towards the rear part of the lobe, but cam was limited to .006" - .008" of endplay with a roller cam button.
On to the valves. 6 of the exhaust valves have some pitting. None of the intake valves have any pitting. I'm really worried because it looks like the rocker arms were not centered (left to right) on the valve tip. I'm not sure how this could happen or how to fix it, especially since the intake valves all look fine.
Anything I'm missing about exhaust valves that would explain how the intake valves are all fine? Again, the only explanation I can think of for the pitting is some trash metal getting under the roller wheel of the rocker and pitting it.
Anybody have any ideas as to what could have caused either of these?
I'll also be sending Comp Cams an email to see what they have to say, but I don't really expect a reply.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Comp cams are pretty good about replyng but I can see now what the reply is gonna be something like "you got 30,000 mile out of a solid roller and your compaining" 
Seriously if I get that out of mine I will be more than happy. That's 5-6 years ! You drove it for that long and just noticed now that the rockers were not centered on the valve tips ? How are the "ears" on those Pro Magnum rockers, usually if they are not centered for that long the roller will dig right into them until they fail.
If it was new engine I would say the valve stems look like the springs were binding but since you drove it that long they probably just wore out, constant banging of the valve train will do that, that is why I use lash caps and just replace the caps, much cheaper than replacing the valve.
The pictures also look like there is rust on the cam ?
Seriously if I get that out of mine I will be more than happy. That's 5-6 years ! You drove it for that long and just noticed now that the rockers were not centered on the valve tips ? How are the "ears" on those Pro Magnum rockers, usually if they are not centered for that long the roller will dig right into them until they fail.
If it was new engine I would say the valve stems look like the springs were binding but since you drove it that long they probably just wore out, constant banging of the valve train will do that, that is why I use lash caps and just replace the caps, much cheaper than replacing the valve.
The pictures also look like there is rust on the cam ?
