Timing chain hitting timing cover!
Thread Starter
Intermediate
Joined: Jun 2000
Posts: 33
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From: Newnan Georgia
Timing chain hitting timing cover!
I have a bb with a Comp Cams xe 268h. It has about 500 miles since rebuild. Lately, I have started hearing a metallic pinging noise. It would last for about 15 seconds, then go away. It might come back about 5-10 minutes later. At first, from the sound of the noise, I thought the fan might be hitting the shroud. One day I happened to have a timing light on the engine as the sound came back. The timing mark started to jump all over the place. When the noise went away, the timing stayed steady. I took the timing cover off, and sure enough the chain had been hitting the cover.
I called the Comp Cams help line and the tech said he had never heard of a flat tappet cam walking and hitting the cover. He said he had no clue and his only suggestion was the distributor gear could be worn letting the cam move forward. I looked at the gear and it doesn't appear to be badly worn. It does have some wear, but without a new one to compare it with I am just guessing.
Has anyone come across this problem before? Any suggestions would be greatly appreciated.
I called the Comp Cams help line and the tech said he had never heard of a flat tappet cam walking and hitting the cover. He said he had no clue and his only suggestion was the distributor gear could be worn letting the cam move forward. I looked at the gear and it doesn't appear to be badly worn. It does have some wear, but without a new one to compare it with I am just guessing.
Has anyone come across this problem before? Any suggestions would be greatly appreciated.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Make sure the distributor is fully seated. I have heard of a distributor sitting just a bit too high in the bore and causing all kind of problems. May not be the case but it's something to look into. Also, have you had any block work done where maybe the cam plug at the back might have been installed too far forward?
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Maybe pull the valve covers and run the engine with oil splash clips, and watch the lifters to make sure they are all spinning.
I did that once and saw that several were not spinning as they are meant to. Wasn't causing problems but it might be a symptom of something you have going on.
Thread Starter
Intermediate
Joined: Jun 2000
Posts: 33
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From: Newnan Georgia
Maybe pull the valve covers and run the engine with oil splash clips, and watch the lifters to make sure they are all spinning.
I did that once and saw that several were not spinning as they are meant to. Wasn't causing problems but it might be a symptom of something you have going on.
I did that once and saw that several were not spinning as they are meant to. Wasn't causing problems but it might be a symptom of something you have going on.
Burning Brakes
Joined: Dec 2007
Posts: 952
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Burning Brakes
Joined: Dec 2007
Posts: 952
Likes: 0
Maybe pull the valve covers and run the engine with oil splash clips, and watch the lifters to make sure they are all spinning.
I did that once and saw that several were not spinning as they are meant to. Wasn't causing problems but it might be a symptom of something you have going on.
I did that once and saw that several were not spinning as they are meant to. Wasn't causing problems but it might be a symptom of something you have going on.
NCM Grand Opening Veteran
Joined: Sep 2005
Posts: 20,979
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From: South of giving a damn
St. Jude Donor '11, '17
Makes me wonder if the cam is a roller & not a flat tappet grind. Did you buy the cam & lifters as a kit or separately? Even if the rear plug was installed too far in, the cam should still stay to the back & not move around. How much slop does the chain have in it?
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Burning Brakes
Joined: Feb 2000
Posts: 1,246
Likes: 1
The cam sits in the block under a slight angle and therefore the flat tappets pushing down on the (ground tapered) lobes keep the cam from moving forward. This is also what makes the lifters spin. Like was said above, a non spinning lifter is a lifter wearing into the cam.
The chain has nothing to do with keeping the cam in the block. If anything you could install a cam button.
Are you absolutely certain you have a flat tappet cam in there?
The chain has nothing to do with keeping the cam in the block. If anything you could install a cam button.
Are you absolutely certain you have a flat tappet cam in there?
Last edited by V-Twin; Oct 28, 2008 at 11:53 AM.
Thread Starter
Intermediate
Joined: Jun 2000
Posts: 33
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From: Newnan Georgia
I will need to go back through my receipts and check the cam part number. The chain has very little slop as it is brand new also.
Thread Starter
Intermediate
Joined: Jun 2000
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From: Newnan Georgia
The cam sits in the block under a slight angle and therefore the flat tappets pushing down on the (ground tapered) lobes keep the cam from moving forward. This is also what makes the lifters spin. Like was said above, a non spinning lifter is a lifter wearing into the cam.
The chain has nothing to do with keeping the cam in the block. If anything you could install a cam button.
Are you absolutely certain you have a flat tappet cam in there?
The chain has nothing to do with keeping the cam in the block. If anything you could install a cam button.
Are you absolutely certain you have a flat tappet cam in there?
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
You might have to 'dimple' the cover with a socket if it's too tight. You can also buy a timing cover for a Gen1 engine block using a retrofit roller cam, and they are stamped for the extra room you might need for the button. You buy the buttons with a retainer clip that bolts to the front of the cam on top of the gear.
Burning Brakes
Joined: Feb 2000
Posts: 1,246
Likes: 1
You might have to 'dimple' the cover with a socket if it's too tight. You can also buy a timing cover for a Gen1 engine block using a retrofit roller cam, and they are stamped for the extra room you might need for the button. You buy the buttons with a retainer clip that bolts to the front of the cam on top of the gear.
Burning Brakes
Joined: Jan 2007
Posts: 1,057
Likes: 4
From: Concord Calif
The cam sits in the block under a slight angle and therefore the flat tappets pushing down on the (ground tapered) lobes keep the cam from moving forward. This is also what makes the lifters spin. Like was said above, a non spinning lifter is a lifter wearing into the cam.
The chain has nothing to do with keeping the cam in the block. If anything you could install a cam button.
Are you absolutely certain you have a flat tappet cam in there?
The chain has nothing to do with keeping the cam in the block. If anything you could install a cam button.
Are you absolutely certain you have a flat tappet cam in there?
Well almost right. The cam shaft does not or is not suppose to be on any angle, it should be square to the crank. But the lobes them selves do have an angle to them to cause them to spin when in use. This same angle is one way on some lobes and the other way on the rest of the lobes. So when the lifter is loaded to the cam lobe it will push the cam back to the block. If to many lobes are angled in the wrong direction depending on which way they are off it will either over load the front of the block or push the cam forward. But in all the years I have been building engines I have only seen this prolem one time on a slant six engine. Now if the cam has a lot of lobes wearing down and worn this taper off as Durango Boy suggested this could be your problem. Also if the chain spockets are out of alignment this would also cause a prolem like you seem to have, check them closely.
Drifting
Joined: Oct 2007
Posts: 1,254
Likes: 5
From: Brown Summit North Carolina
COMP owed you more of an attempt to help than what you described.
David
Thread Starter
Intermediate
Joined: Jun 2000
Posts: 33
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From: Newnan Georgia
The number on your receipt is not conclusive. The critical # is what is on the cam. Packing / picking errors can occur. You may not have got what you ordered or were billed for.
I agree, their help line certainly was not much help.
I agree, their help line certainly was not much help.
Thread Starter
Intermediate
Joined: Jun 2000
Posts: 33
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From: Newnan Georgia
Instructor
Joined: Oct 2008
Posts: 187
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cam button install
some cam buttons are held in place with a cam lock plate,it depends
on which one you prefer to use.
One type uses a thrust bearing I had one of these come apart ,I won,t use them again.
The one I recommend is the solid aluminun type.You will have to set the clearance on any of these buttons.
5-10k run out works for me.
I would purchase the longer button so as to adjust the length properly
If you have access to a lathe it makes it very simple to fit it.
Also don,t try to put a dimple in a cast aluminum cover it can and will crack ,done that.
Hope i was helpful
on which one you prefer to use.
One type uses a thrust bearing I had one of these come apart ,I won,t use them again.
The one I recommend is the solid aluminun type.You will have to set the clearance on any of these buttons.
5-10k run out works for me.
I would purchase the longer button so as to adjust the length properly
If you have access to a lathe it makes it very simple to fit it.
Also don,t try to put a dimple in a cast aluminum cover it can and will crack ,done that.
Hope i was helpful