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Old 09-17-2007, 09:38 PM   #1
BiGtUrBo
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Default Engine Gurus needed- wear on cam buckets

Can someone tell me why there are 2 different wear patterns on these buckets ? This is probably not normal wear. What can be causing this ? These are intake buckets from an STI.

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Old 09-17-2007, 11:07 PM   #2
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Different clearance and one spun more than the other?
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Old 09-18-2007, 09:43 AM   #3
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all the other buckets have wear similiar to the bucket on the right...only the left bucket had a different wear patern. It doesn't look like this bucket is spinning.Will this wear out the cam and what could be causing it not to spin ?
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Old 09-18-2007, 12:58 PM   #4
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Quote:
Originally Posted by BiGtUrBo View Post
all the other buckets have wear similiar to the bucket on the right...only the left bucket had a different wear patern. It doesn't look like this bucket is spinning.Will this wear out the cam and what could be causing it not to spin ?

What's the sides of the bucket look like?
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Old 09-18-2007, 06:25 PM   #5
Jeremy@Cobb
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The bucket on the right looks close to normal... towards the outside appears to look odd/ broken up (stress cracks).

The left bucket appears to have a slightly looser lash (more area on the outside which does not have contact with the lobe). I also agree this bucket is obviously not spinning.
- check for coil bind if buckets are cupped
- check OD of the buckets compare to factory spec.
- check for burrs in the bucket bores
- make sure there is no contamination blocking oil from getting to the bucket bores

1- always polish the bucket bores to make sure they do not have any burrs or scoring which could prevent a bucket from spinning or moving up and down.

2- when the valvetrain is installed make sure the valve spring compressor does not hit the lifter/bucket bore.

3- when a head is rebuilt, ported, etc.
Remove the plugs for the oil passages in the heads and clean these areas out with a brush in a solvent tank, use high pressure water afterwards, then dry with air.

4- before assembly make sure the buckets spin freely.
Also I like to Mic. every bucket, I have gotten a few new buckets from time to time which were out of spec.

- J.
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Old 09-18-2007, 10:36 PM   #6
BiGtUrBo
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Quote:
Originally Posted by Jeremy@Cobb View Post
The bucket on the right looks close to normal... towards the outside appears to look odd/ broken up (stress cracks).

The left bucket appears to have a slightly looser lash (more area on the outside which does not have contact with the lobe). I also agree this bucket is obviously not spinning.
- check for coil bind if buckets are cupped
- check OD of the buckets compare to factory spec.
- check for burrs in the bucket bores
- make sure there is no contamination blocking oil from getting to the bucket bores

1- always polish the bucket bores to make sure they do not have any burrs or scoring which could prevent a bucket from spinning or moving up and down.

2- when the valvetrain is installed make sure the valve spring compressor does not hit the lifter/bucket bore.

3- when a head is rebuilt, ported, etc.
Remove the plugs for the oil passages in the heads and clean these areas out with a brush in a solvent tank, use high pressure water afterwards, then dry with air.

4- before assembly make sure the buckets spin freely.
Also I like to Mic. every bucket, I have gotten a few new buckets from time to time which were out of spec.

- J.
thanks Jeremy, thats some good info there. What would happen to either the bucket or camshaft if one was to continue using a non spinning bucket such as the one on the left ? ie. if these 2 buckets were left in the heads as if nothing had happened ?
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Old 09-19-2007, 01:18 PM   #7
Jeremy@Cobb
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The bucket would have eventually faild, since it wasnt able to take the stresses evenly.

If the bucket faild and broke it very well could have taken out your whole engine.

- J.
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Old 09-19-2007, 04:25 PM   #8
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Quote:
Originally Posted by Jeremy@Cobb View Post
Also I like to Mic. every bucket, I have gotten a few new buckets from time to time which were out of spec.
I've gotten a few like this too and they can cause some expensive issues if you don't catch 'em.
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Old 09-20-2007, 01:48 PM   #9
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All of these clearances and tolerances are basic measurements that should be taken and checked.
Especially when you are installing new parts that were never ran in the engine before.

In my mind this is exactly why it is worth using an experienced engine builder, not someone who has built less than a handful of the specific engine you are dealing with.

This is not to say someone who hasnt built the specific engine before cannot acomplish the task, but without expereince there are alot of little things to look at asside from the basic standard measurements that are checked, noted, and adjusted if need be.

- J.
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Old 09-20-2007, 07:52 PM   #10
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yup...especially with our unusual boxer motors. They are by far the second most odd motor I have ever built.
They take the cake for odd porting though
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Old 09-20-2007, 10:35 PM   #11
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thanks for the info guys.....i put that left bucket back in to see if it would spin freely and it does....what gives ??

Would a faulty bucket wear down the camshaft lobes over a period of time ?

thanks.
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Old 09-23-2007, 02:52 PM   #12
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The wear pattern on the bucket on the left is most likely caused by an incorrectly ground, or worn, or broken in camshaft lobe...

Cam lobes are ground at a very slight angle to promote lifter rotation...
(There is an exception to this, on a true roller camshaft the lobes are either flat or slightly rounded...)

Look at the wear pattern on that camshaft lobe vs another lobe and see if it is worn different.... If it is, you found the problem...

This can also be caused by either the bottom of the bucket, or the top of the valve not meeting squarely... IE: machined wrong..

Post pictures of the cam lobe wear...
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Old 09-23-2007, 10:55 PM   #13
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Quote:
Originally Posted by shvrdavid View Post

Post pictures of the cam lobe wear...
this is a pic of the corresponding cam to those buckets, the lobe on the left corresponds to the left bucket....pic taken before disassembly.

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Old 09-23-2007, 11:11 PM   #14
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notice the wear on the lob on the left...surface looks different...almost like its scuffed...kinda hard to tell from the pic though
can you take a straight on silhuoette like picture of them ?
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Old 09-24-2007, 05:08 PM   #15
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Is it me, or is the lower side of the left lobe still shiny???
I am assuming by the picture that this is the rear intake valve on cylinder number 1....

What is the valve guide clearance of that guide???
Looks like it may be to tight and it was sticking...

What work has been done to the heads???
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Old 09-24-2007, 10:41 PM   #16
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You are both correct. The lobe on the left has a different wear pattern. Yes, it is shiny not all the way across the lobe but about 3/4 across.

The heads have 1 mm oversized intake and exhaust valves with dual springs and Ti retainers all from Ferrea. The valve clearance was in spec with the cam manufacturer's specs when checked before disassembly. Both sides(lobes) had the same clearance.

If it was too tight and sticking would it not cause the valve to stay open and not fully close ?

Thanks.
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Old 09-25-2007, 11:07 AM   #17
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I was referring to the valve to guide clearance, not the lash setting...
I looks to me like the valve was sticking in the guide, then slamming shut...
Were there any codes in the ecu???

Is the head off of the engine???
If it is, look at the piston to see if the valve has made contact with the piston...
Then take the spring off of that valve and check the valve stem to guide clearance... Looks to me like it was to tight by the wear pattern on the cam lobe and the bucket... I might be wrong, but I would start looking at the guide...
Let us know what you find...
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Old 09-25-2007, 11:23 AM   #18
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After my last post, I thought about something else...
Ferrea valves are available with different stem diameters...
I think 5.96mm and 5.97mm (for a 6mm guide)...
Ask whomever did the heads if all of the guides were sized for the stem diameter of the valves that you got from Ferrea...
0.0005 to tight on the clearance is all it takes for it to stick when the guide expands...

Last edited by shvrdavid; 09-25-2007 at 11:31 AM.
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