Trashed a lobe on my cam..anyone else ?
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TECH Apprentice
Joined: Jun 2002
Posts: 355
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From: Earth
Trashed a lobe on my cam..anyone else ? After a little over 500 miles on my new 422 an unusual - and not too distinct tapping noise began to appear at idle. However, since the tapping went away after slight warming up, I ignored it as being nothing sufficient to concern myself or worry about.
Last week I decided to change cams, ordered the new profile and when it arrived today, pulled the first cam. To my horror one lobe, and only one lobe, was marfed up on the opening and closing ramps. The respective lifter is flat spotted and the plastic alignment tray has a divot worn in where the lifter indexes.
All the other lobes and lifters look virtually new...I mean you are hard pressed to tell they were ever run. The valve springs all have the same seat and open pressure (within 5 lbs) and the rockers arms and pushrods are all pristine.
Anybody else lose a cam and lifter this way? Any suggestions on the root cause?
Last week I decided to change cams, ordered the new profile and when it arrived today, pulled the first cam. To my horror one lobe, and only one lobe, was marfed up on the opening and closing ramps. The respective lifter is flat spotted and the plastic alignment tray has a divot worn in where the lifter indexes.
All the other lobes and lifters look virtually new...I mean you are hard pressed to tell they were ever run. The valve springs all have the same seat and open pressure (within 5 lbs) and the rockers arms and pushrods are all pristine.
Anybody else lose a cam and lifter this way? Any suggestions on the root cause?
Re: Trashed a lobe on my cam..anyone else ? Usually if you have a bad cam core, more than one lobe and lifter will show signs of wear. Sounds to me like the lifter guide started to allow the lifter to rotate slightly. Then the lifter wheel will lose indexing to the cam lobe which will cause excessive wear on the cam ramps. Change the pastic lifter guide on the one in question.
A year ago I had what I deemed a bad cam core. Several lobes on the core were excessively pitted around the entire lobe. The car had been drive no more than 300 miles. The cam in question was replaced under warranty.
Good luck,
Richard
A year ago I had what I deemed a bad cam core. Several lobes on the core were excessively pitted around the entire lobe. The car had been drive no more than 300 miles. The cam in question was replaced under warranty.
Good luck,
Richard
Staging Lane
Joined: Sep 2002
Posts: 61
Likes: 0
From: Highland Park, Illinois
Re: Trashed a lobe on my cam..anyone else ? I doubt you have a bad cam core. That's very rare with roller cams. I'm assuming that ample oil pressure exists and your running non-adjustable rockers. Since it's apart, I would first check for a collapsed lifter or bent pushrod. If both are OK then check your valve spring for breakage and retainers for contact with rocker arms. If they're OK then I would assume you have either a slightly bent valve or your valve stem to guide clearance is too tight. Hope this helps.
