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Old 11-29-2013, 07:56 PM   #1
mboulton
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Default My cam ate my bucket

Anyone experience a Kelford 220-C cam or similar profiled cam eating a bucket? Proper break in procedure and oil pressure present. Lash was all proper.

I had heard of this happening in the past, but nothing recent.

I am now dealing with this problem, and those involved are uncertain on how to prevent this from happening again.

It ate one of my intake buckets on cylinder three.


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Old 11-29-2013, 08:00 PM   #2
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Old 11-29-2013, 09:18 PM   #3
Junior2JZ
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Improper clearance, been there done that. I blamed Kelford, I was taught why it happens by a completely outside source and have not had any more failures.
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Old 11-29-2013, 09:24 PM   #4
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Quote:
Originally Posted by Junior2JZ View Post
Improper clearance, been there done that. I blamed Kelford, I was taught why it happens by a completely outside source and have not had any more failures.
What constitutes proper clearance?
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Old 11-29-2013, 09:29 PM   #5
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Quote:
Originally Posted by mboulton View Post
What constitutes proper clearance?
Give HeadGames a call. I can tell you though that it was a clearance issue, haven't had another one since.
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Old 11-29-2013, 09:48 PM   #6
mboulton
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Quote:
Originally Posted by Junior2JZ View Post
Give HeadGames a call. I can tell you though that it was a clearance issue, haven't had another one since.
Much appreciated.

Dave is a great guy.


Mel
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Old 11-30-2013, 05:38 AM   #7
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I'm curious, what valve spec did you use? What was actual clearance?

Subaru spec is I/E .008"/.014" and a lot of times I see people use .008"/.010". I would think it would have to be to tight of valve to cause wear like that as loose one would just be noisy
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Old 11-30-2013, 06:35 AM   #8
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Every time I see one of these posts makes me nervous lol. I installed mine at the crower spec which is tighter then Subaru spec. No issues yet that I know of but I haven't pulled it apart to look either
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Old 11-30-2013, 08:26 AM   #9
john 1badSTI
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did you allow the engine to idle at 1500-2000 for the first 15-20 minutes with a high zinc break-in oil?And were used buckets used with the new cams?And what kind of break-in lube was put on the lobes during assembly?
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Old 11-30-2013, 05:45 PM   #10
mboulton
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Kelford provided cam lube used generously on cam lobes for assembly.
First 20 minutes on engine are 2500 RPM in neutral on Brad Penn Break in Oil
After that Brad Penn 10w40 oil.
Oil changed twice before head noise started. No unusual debris found when first two oil filters were inspected via aircraft oil filter inspection tool.
Cosworth high volume oil pump
Idle speed 1000 RPM, minimum block oil pressure 40 psi, minimum head oil pressure 20 psi (monitored separately at all times) via multigauge.
Head oil pressure sending unit is in the head the cam had the issue on.

Lash Specs at assembly:
passenger head
exhaust .012-.013"
intake .008-.010"

driver head
exhaust .011-.012"
intake .007-.09"


I can't understand why only one intake bucket of two eroded on cylinder #3!!!!!

All eight exhaust buckets maintained their lash, as did 7 of 8 intake buckets.



The LACK of understanding bothers me, as I don't know what to change for this next round.


mel
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Old 11-30-2013, 08:05 PM   #11
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What's the bucket to bucket bore clearance?

Jay
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Old 11-30-2013, 08:21 PM   #12
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Quote:
Originally Posted by Storm View Post
What's the bucket to bucket bore clearance?

Jay
unknown. new buckets and brand spanking new heads. So most likely perfectly within tolerance.
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Old 11-30-2013, 08:28 PM   #13
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maybe it was simply bad luck with debris temporarily blocking the galley exit to that bucket…… resulting in scraping and erosion during an oil starved period…. then continued to erode


I am probably just going to replace the buckets (x4) and intake cam in the passenger side head and try again.


Nobody is offering similar experiences with concise answers.


Ahhhhh to live outside of OEM specs.



mel
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Old 12-03-2013, 05:06 PM   #14
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A surface harness issue on either the bucket or the cam lobe itself. We've also caught new "sticky" buckets and have had to replace them. This prevents them from spinning which will also cause that issue.

Thanks,
Phil Grabow
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Old 12-03-2013, 06:10 PM   #15
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Just a thought but what kind of retainers did you have? If you look at your bucket, it looks like you almost set your lash on the retainer instead of the stem. I've avoided using Ferrera retainers due to this possible reason since they are flat around the stem and if you tip the valves too much you could run into that issue. I always use Supertech retainers due to design.
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Old 07-07-2014, 02:24 AM   #16
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Quote:
Originally Posted by Junior2JZ View Post
Improper clearance, been there done that. I blamed Kelford, I was taught why it happens by a completely outside source and have not had any more failures.
Case solved!

Now we can end this thread: http://forums.nasioc.com/forums/show....php?t=2642831



Credits to subi STile for finding this thread!
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Old 07-07-2014, 10:58 AM   #17
mboulton
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Replaced my heads and using GSC S2 cams now. All new stuff. So far no issues at 5000 miles or so and a track lapping day.

Fingers crossed.
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Old 07-07-2014, 11:03 AM   #18
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Going to use the heads that failed to test changes to the oli feed office in an attempt to get more oil to the valve train. But I don't want to sacrifice global oil pressure while at idle.


Yes I know people are saying that this isn't a oiling issue.


Mel
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Old 07-07-2014, 11:05 AM   #19
mboulton
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This is the orfice in the galleys.
Attached Images
File Type: jpg image-4273925203.jpg (38.6 KB, 103 views)

Last edited by mboulton; 07-07-2014 at 02:13 PM.
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Old 07-17-2014, 03:39 PM   #20
mboulton
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UPDATE

With my GSC S2's running strong in completely new heads, I have been playing around with my failed set of heads that had Kelford cams in them. I have focused on oiling and even built flow rigs to play around with the galley orfices. I could not guarantee a reasonable idle oil pressure without committing to a real build rather than a mock up and therefore stalled in my quest for answers.

The cam clearance issue got me fired up again and seems to be the reason for my failure.

Using clay, I checked the clearances on my cam lobes relative to the case and bucket bores. The failed cam lobe had very little clearance such that the clay left only a smear on the nose of the lobe. The other lobe on cylinder 3 had thick clay remaining. I repeated this test many times and obtained the same results with both cam lobes on cylinder 3.

The machined clearances looked identical for every lobe in the head. I was stumped why the clearance was less for the failed lobe if the machining was uniform throughout. UNLESS......

so I measured the cams and here is what I found.


OEM cam
Intake- uniform at 46mm
Exhaust- uniform at 46mm

Kelford
Intake- 47.5mm rear lobe
48mm front lobe
Exhaust-47.5mm uniform

For a given cylinder the Kelford cams use a larger and smaller lobe combo. Probably to induce a swirl effect whereas OE does not and probably relies soley on barrel type flow.

The chewed up intake lobe on cylinder 3 was the 'larger' lobe that clearly had contact and rounded the shoulders of the cam at the tip of the nose.


So. This is new to me. Maybe everyone else knows that Kelford uses a asymmetrical cam lobe pair for each cylinder, but I did not.

When milling clearance for cams be sure to check each lobe and not just assume uniform lobe profiles.

I hope this helps prevent a future failure for someone.

Mel


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Old 07-17-2014, 04:36 PM   #21
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http://forums.nasioc.com/forums/show....php?t=2642831

EDIT: whoops, someone already posted this.
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