Home » Public Forums » GMCnet » Cam wear question. (Suspicious cam)
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| Re: [GMCnet] Cam wear question. [message #237702 is a reply to message #237690] |
Mon, 27 January 2014 19:29   |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Harold,
I don't qualify as a guru, but the wear patterns on those upper two lobes
did NOT get there while in the shipping box.
Maybe only the two lower lobes are new/no run? :-)
Ken H.
On Mon, Jan 27, 2014 at 7:47 PM, Harold wrote:
>
>
> Wondering if I could bug the motor gurus again for another opinion. This
> is supposedly a new, non-run/no break-in cam.
>
> http://www.gmcmhphotos.com/photos/mechanical/p52613-455-cam.html
>
> Whaddaya think?
>
> Thanks, Woody.
>
>
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Ken Henderson
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www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: Cam wear question. [message #237705 is a reply to message #237690] |
Mon, 27 January 2014 19:39 |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
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Just to clarify, this is in a motor you have and someone told you it was new?
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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| Re: Cam wear question. [message #237714 is a reply to message #237712] |
Mon, 27 January 2014 20:45 |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
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Well in my less than professional opinion that is significant cam wear, and certainly not what I would expect from a new cam. Show the photo to the folks you bought it from and see what they say.
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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| Re: Cam wear question. [message #237739 is a reply to message #237690] |
Tue, 28 January 2014 00:11 |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma: 3
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Harold,
I'm certainly not the engine guru but for what its worth here is my very recent experience with a new cam .
Did you try dragging your finger through what looks like a wear pattern on the upper lobes?
Earlier this month I helped Miguel at MGMGMC with the final assembly on my rebuilt 455. I was surprised to see the same "pattern" on the new cam lobes after we installed the cam, lifters, push rods and rockers and then spun the engine over by hand a few time.
Turns out it was just the cam lube smeared by the lifters and it wipes right off leaving no pattern..
The third lobe down in your picture has a gob of the lube not yet flattened and smeared.
I was also surprised at the appearance/texture/roughness of the new cam lobes as it comes out of the box. It looked like the lower lobes in your picture.
We finished the assembly and mounted it in the test stand. Next day it fired right up and ran like a top while breaking in.
If your intake manifold is still off-spin the crank a couple of times and then wipe a lobe off and see if the pattern disappears.
Please report back.
Good luck.
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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| Re: [GMCnet] Cam wear question. [message #237753 is a reply to message #237712] |
Tue, 28 January 2014 07:05 |
Jim Bounds
Messages: 842
Registered: January 2004
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The first couple of break in minutes were not good to that cam. Was not run with break in oil from what I can see. Surface wear is flatter are the lobe comes up, 2 surfaces are already pitted. Could be wrong, why did someone open the motor up?
Jim Bounds
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On Monday, January 27, 2014 9:43 PM, Harold <jal747@mac.com> wrote:
This is a fresh rebuild crate engine I picked up last week, which was special ordered with a new Comp Cams 42-207-4 cam installed. It supposedly had only been cold spun to test rotating body and compression. I only noticed the cam pitting and wear when I pulled the valley splash shield to replace it with a Mondello shield. Everything else (except for the rear galley plug hole and RWD main cap bolts) seems up and up. I'll reserve any further builder comments for now.
Otterwan wrote on Mon, 27 January 2014 18:39
> pyolet wrote on Mon, 27 January 2014 16:47
> > Wondering if I could bug the motor gurus again for another opinion. This is supposedly a new, non-run/no break-in cam.
> >
> > http://www.gmcmhphotos.com/photos/mechanical/p52613-455-cam.html
> >
> > Whaddaya think?
> >
> > Thanks, Woody.
>
>
> Just to clarify, this is in a motor you have and someone told you it was new?
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| Re: [GMCnet] Cam wear question. [message #237767 is a reply to message #237753] |
Tue, 28 January 2014 07:56 |
Jim Bounds
Messages: 842
Registered: January 2004
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Just read the rest of the thread. The problem is not fault of the cam if that motor has few miles on it, it's the way someone first ran it. Does not take much to lunch a cam. This was my flat tapped profile so I know the grind. It should not have gotten that much wear so fast. I would replace the cam and lifters. May also want to look at the main bearings. Does it have a bolt on oil pickup tube on the oil pump?
Jim Bounds
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On Tuesday, January 28, 2014 8:05 AM, Jim Bounds <gmccoop@yahoo.com> wrote:
The first couple of break in minutes were not good to that cam. Was not run with break in oil from what I can see. Surface wear is flatter are the lobe comes up, 2 surfaces are already pitted. Could be wrong, why did someone open the motor up?
Jim Bounds
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On Monday, January 27, 2014 9:43 PM, Harold <jal747@mac.com> wrote:
This is a fresh rebuild crate engine I picked up last week, which was special ordered with a new Comp Cams 42-207-4 cam installed. It supposedly had only been cold spun to test rotating body and compression. I only noticed the cam pitting and wear when I pulled the valley splash shield to replace it with a Mondello shield. Everything else (except for the rear galley plug hole and RWD main cap bolts) seems up and up. I'll reserve any further builder comments for now.
Otterwan wrote on Mon, 27 January 2014 18:39
> pyolet wrote on Mon, 27 January 2014 16:47
> > Wondering if I could bug the motor gurus again for another opinion. This is supposedly a new, non-run/no break-in cam.
> >
> > http://www.gmcmhphotos.com/photos/mechanical/p52613-455-cam.html
> >
> > Whaddaya think?
> >
> > Thanks, Woody.
>
>
> Just to clarify, this is in a motor you have and someone told you it was new?
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| Re: Cam wear question. [message #237790 is a reply to message #237690] |
Tue, 28 January 2014 10:02 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Woody,
While the apparent wear pattern on the cam is disquieting, the pitting is even more so. If the wear pattern over the lobes does not feel rough to a fingernail, it may be useable. Is there a chance that the cam or assembled engine was stored poorly at some point? That much of a wear pattern can show up just form the rolling required for a proper assembly. But, if the surface was pitted at the nose of the lobes, there may be real problems. Find a machine shop friend and borrow his surface finish comparator. (It is just a plate with different finishes to compare to what you have by finger nail.)
Someone suggested that you wipe the lobes carefully and see how much of that pattern goes away. That would be a very good idea.
Cam surface finish is real picky, and yours may (I wrote may for a reason) may have been damaged too much to be usable. If it is, it will finish off the cam followers in short order when you try to run it.
At this point, it would also be trivial (all things considered) to unload the valve gear and look at the faces of at least a few followers. If they aren't scarred at all, you may be good to go with what you have.
Matt - the engine lab refugee
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Cam wear question. [message #237837 is a reply to message #237806] |
Tue, 28 January 2014 16:31 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Harold,
The reason I asked if it was an S&J engine is because if you watch their video's they spin (not run) the engine on a test stand
before they ship it. According to the video below they spin it at 300 & 600 rpm. All the info I've ever read, seen, or heard about
breaking in a new flat tappet cam is that the engine needs to be run at 2000 rpm for 20 minutes.
https://www.sandjengines.com/
Disclaimer: S&J has been asked about this and they have noted they've NEVER had a problem with cams in any engine they build. To
back this up there are a number of guys in the Pacific Northwest that have S&J engines and are happy with them. IIRC Jerry Work is
one of them.
You mentioned that your builder spun the engine, and that the engine was not an S&J engine. Do you know the procedure he used?
Regards,
Rob M.
Sydney, Australia
-----Original Message-----
From: Harold
The mottled finish is not residual lube or rough to the finger tip or finger nail and covers every cam lobe not contacted by a
lifter during the spin-test. Assembler coated the entire cam with "pure zinc" prior to install, and had positive external oil
pressure during the spin-test on a dedicated spin-up test rig. Could it be electrolyzed zinc or whatever they used?
Spoke with Comp Cams Tech Supp, sent them pics and they're investigating....mtf.
Jim, the long block is in build up so never been operational or had the intake manifold on.
BTW thanks for all the replies guys. I have dreamed of a Koba motor for years, but way outa reach. I would've built the motor
myself if there was a decent machine shop near me. This crate long option seemed best after the research. Hope it pans out and I
can get on the road and head south soon. Back to painting accessories.
W.
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Cam wear question. [message #237844 is a reply to message #237690] |
Tue, 28 January 2014 17:30 |
pyolet
Messages: 78
Registered: August 2006
Location: Helena, MT
Karma: 0
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Rob, the shop I used has the same SimTest set up and procedures. They run the test until all the lifters pump oil. AFAIK, the reason for the 2000-2500 rpm break in is to insure adequate oil pressure and flow to the cam bearings and lobes. The tester provides 50psi warmed oil directly to the oil galley, so the bearings are floating for the most part, and the only issue is adequate cam lobe lubrication after all the assembly lube is wiped away.
I'm still stumped by the discoloration on all the lobes where they had not made contact with the lifters. I don't think it's pitting, but looks more like a micro build up or deposit, perhaps from the pre-assembly zinc agent they used. I added a couple more pics to the first post.
I've asked Comp Cams whether the SimTest procedure has had any history of detrimental effects with their flat tappet cams and they're looking into it.
For now, since the builder will warranty it, I'm going forward with the assembly and run it like I stole it....after I break in the cam per Comp Cams instructions that is.
W.
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| Re: [GMCnet] Cam wear question. [message #237854 is a reply to message #237844] |
Tue, 28 January 2014 18:47 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Harold,
This is the first time I've read this statement; "AFAIK, the reason for the 2000-2500 rpm break in is to insure adequate oil
pressure and flow to the cam bearings and lobes."
I did some poking around and found this:
http://www.youtube.com/watch?v=re-VqHO3cH8&feature=youtu.be
At 1:28 into the video the narrator states; "Bring the engine speed to 2000 - 2500 rpm"
At 1:30 into the video the narrator states; "Slower engine speeds will not supply and adequate amount of oil to the cam"
At 1:38 into the video narrator states; "Spend at least 30 minutes varying the engine speed from 2000 to 2500 rpm."
This begs the following question:
According to this video the 2000 - 2500 rpm for oil supply can one assume that if you "spin" the engine at a lower rpm WITH adequate
oil supply for 20 to 30 minutes you've broken in the cam?
Regards,
Rob M.
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: Harold
Rob, the shop I used has the same SimTest set up and procedures. They run the test until all the lifters pump oil. AFAIK, the
reason for the 2000-2500 rpm break in is to insure adequate oil pressure and flow to the cam bearings and lobes. The tester
provides 50psi warmed oil directly to the oil galley, so the bearings are floating for the most part, and the only issue is adequate
cam lobe lubrication after all the assembly lube is wiped away.
I'm still stumped by the discoloration on all the lobes where they had not made contact with the lifters. I don't think it's
pitting, but looks more like a micro build up or deposit, perhaps from the pre-assembly zinc agent they used. I added a couple more
pics to the first post.
I've asked Comp Cams whether the SimTest procedure has had any history of detrimental effects with their flat tappet cams and
they're looking into it.
For now, since the builder will warranty it, I'm going forward with the assembly and run it like I stole it....after I break in the
cam per Comp Cams instructions that is.
W.
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Cam wear question. [message #237869 is a reply to message #237854] |
Tue, 28 January 2014 20:36 |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma: 3
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Senior Member |
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Rob.
I believe the answer to that is "NO". Without combustion there is no significant heat generated which I assume is essential for the "break in".
The lower speed spinning of the crank or spinning the oil pump is a check to insure oil pressure and flow through the entire engine.
In my case it seemed to take FOREVER get oil to spit from the last push rod through the rocker. Only after that were we satisfied to install the rocker covers and fire the monster up for the actual break in.
I think that after Woody checks everything out with the builder he will be satisfied and "OK" to go forward.
New Melling cam lobes look surprisingly rough "out of the box" just like the photo of his Koba cam.
All the chatter on the net makes all of us paranoid.
That may be a good thing!
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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| Re: Cam wear question. [message #237889 is a reply to message #237690] |
Tue, 28 January 2014 22:45 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Senior Member |
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That Cam sure looks to me like the Parkerized Cams I used to get from a Local engine machine shop. (We used to get everything machined and then assembled the engines ourselves) (Looks rougher than it really is) The Parkerizing keepes the surfaces from corroding but if I recall it also seemed to feel a bit "slippery"
The coating comes off very fast and it might very well begin to look that way with only a few hand revolutions. (I don't really remember looking at the cam before actually running the engine.
BUT!!!
I can't be there to actually see the cam so this is only a possibility!!!!
Best Regards
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: Cam wear question. [message #237895 is a reply to message #237690] |
Tue, 28 January 2014 23:23 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Senior Member |
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For your Information: Here is one example of a camshaft regrinding Company that Parkerizes it's camshafts It's website is:
http://www.blakesreman.com/remanufactured-camshafts/
Here is a quote from the Web Page explaining the Parkerizing process.
| Quote: |
Pakerizing Process for Rebuilt Camshafts
The founder of Blake’s Remanufacturing, Robert Blake, discovered long ago that Parkerizing rebuilt camshafts and lifters helped them hold oil during the start-up process, thus making a smooth clean start-up that was less hard on the engine. Parkerizing is a three bath process that applies a non metallic absorptive coating to the outside surface of the rebuilt camshaft and lifters. This permits rapid break-in without scuffing the cam lobes. It also helps prevent against corrosion for the rebuilt camshafts and lifters in humid climates, and those stored for extended periods of time.
The mains on the remanufactured camshafts are taped and not parkerized. When the remanufactured camshafts have completed Parkerizing we spray them with a dry graphite film lubricant, this also protects against corrosion and acts as a lubricant to prevent scuffing, scoring and seizing. Both processes will give the reman camshafts a Dark Charcoal Color. It is important once the reman camshaft has been parkerized to not remove the graphite spray or Parkerizing. We stand by this process 100% and believe it to be the most effective way to protect our reman camshafts for long durability. If for any reason you don’t want Parkerizing or graphite spray applied to your remanufactured camshaft please let us know ahead of time and we can accommodate the request.
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Best Regards
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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