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opinions on cam breakin Pages: 12

mhamilton on Wed December 14, 2005 8:24 PM User is offlineView users profile

Year: 80
Make: Chevy
Engine Size: 229

I have been looking for opinions on proper cam breakin for a stock small block engine, I'm getting tired of all the super-technical race engine procedures, or those who think engine break-in is a gimmick. I know many of the people on this forum are very knowledgeable and can give me a straightforward answer.

Long story short, 20k miles ago I rebuilt the 229 V6 in my Chevy. Now valve noise and vibration is driving me crazy, I've narrowed it down to valvetrain (rough idle, vacuum gauge rapid fluctuation, ticking noises, decreasing performance). When I built the engine, coated the cam with Moly lube, my father and I dropped it in, and he preceded to adjust the lifters while it idled, no formal breakin period. I have not pulled the intake to look, but I have a feeling the cam lobes are wiped.

If I do find I have to replace the cam and lifters, I want to do it the right way. I will set the lifter preload per the GM manual and add GM break-in oil additive. What about startup? Is it really going to kill the cam if I have to crank the engine for more than 5 seconds before getting it up to 2000 rpm? How long is long enough to break it in?

Oh, if I have a 2nd bad cam, I will flush the oil galleys, if that will help clear out any metal particles.

Thanks for any suggestions,

-Michael

Chick on Wed December 14, 2005 8:34 PM User is offlineView users profile

I would pull the valve covers and intake and check the lobes. Just a thought but it may be bad lifters, or a burned valve..You have to know before doing anything..Also, may have a lifter to tight..
Questions
1. Did you change the oil pump?
2. Pre load the lifters before installation?
3. Adjust them properly?

As far as breakin, just drive it normally for the first 500 miles always worked for me..then change the oil, ad drive it like you stole it...

PS: Pull the valve covers and check that the rockers are all moving the same, feel each one by pushing on them and "feel" the throw of the push rod..Could be the rocker(s) loosened up a bit too....

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Edited: Wed December 14, 2005 at 8:50 PM by Chick

mhamilton on Wed December 14, 2005 9:00 PM User is offlineView users profile

Oil pump was changed.

Lifters were not fully pre-loaded before first startup. Lash was adjusted while the engine was idleing.

Since the rebuid I've adjusted the valve lash twice in an effort to stop the noise. First time did the adjustment hot, that made things smooth for about a week, but didn't change the vacuum fluctuation. It got very rough again, and the 2nd time I adjusted the lash exactly per the GM manual, with the engine off, etc, etc.

I have checked the rockers, and the studs. I was also thinking the lock nuts may be backing off, but the valve noise never goes away, so that doesn't seem like the root cause. I'm certainly hoping that I won't have to pull the cam out, but it seems more and more likely I will.

Chick on Wed December 14, 2005 9:08 PM User is offlineView users profile

Well, it's been a L O N G time since I worked on engines, but what you are describing sounds like a burned valve and/or collapsing lifters..But you will know when you pull the valve covers to check the throw,or the intake to visually check the lobes..On mechanical lifters, the cam would most likely be the cause, but hydraulic lifters "adjust" so the noise should not be as evident as the rough running engine

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Chick on Wed December 14, 2005 9:14 PM User is offlineView users profile

Oh, when you pull the valve covers, feel for the noisy lifters, and when you pull the intake take them out first and see if they are "cupped" on the bottoms..If they are, change the lifters if no sign of cam wear, as they can and will detroy the new cam...Whenever I changed a cam, the lifters got changed too, like changing an O tube if you retrofit an AC system.. Cam failures are not heard of very often any more......Hope this helps.

PS: Did you check the oil pump pressure? That is a more common failure, especially if a rebuilt or not properly loaded when installed..Just throwing out thoughts here..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Edited: Wed December 14, 2005 at 9:15 PM by Chick

clueless on Wed December 14, 2005 9:17 PM User is offline

Adjust valve lash cold (with lifters on back of cam lobes [Use valve adjust sequence] twist pushrod while tightening when it stops turning thats zero lash, now tighten 1/8-1/4 turn---Be paitent when you do this get the zero as close as you can).

Make sure EVERYTHING on engine is ready to run, coolant, fuel etc.

On FIRST start run at 1500-1800 RPM for 45 minutes, do not shut off.

Thats about all there is to it. Older pushrod V Chevy engine cams are real bad about needing this. Any other make and you don't need to do this.

clueless on Wed December 14, 2005 9:19 PM User is offline

All you can really do is measure the pushrod lift with a dial guage and see if some are way shorter than the others. Thats the only way to see if the cam has failed.

Chick on Wed December 14, 2005 9:54 PM User is offlineView users profile

You may also want to post the question over at Bat Auto they have some pretty sharp mechanics helping the DIY'er...Just a though.

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Tony on Thu December 15, 2005 1:03 AM User is offlineView users profile

First, what model is this engine in?
Second, why was the cam replaced and what other work was done on the engine when the cam was replaced? Were the cam bearings replaced?


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BAT Auto Technical

Chick on Thu December 15, 2005 6:41 AM User is offlineView users profile

Look at that, you didn't even have to go to Bat Auto, they came to you...You're in good hands now..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

mhamilton on Thu December 15, 2005 11:24 AM User is offlineView users profile

Quote
Originally posted by: Tony
First, what model is this engine in?

Second, why was the cam replaced and what other work was done on the engine when the cam was replaced? Were the cam bearings replaced?


80 Chevy Malibu

Engine was overhauled, original 'soft' cam was wiped clean, plus usual wear of a 120k mile engine. Block was dipped and bored over, all new bearings, heads were redone with new valves and springs.

Perhaps I'm opening a can of worms by asking what personal opinions people have about cam breakin... I guess my real question is what did GM do to break in the cams on their new engines?

bohica2xo on Thu December 15, 2005 12:26 PM User is offline

MHamilton:

Genital Motors forgot how to heat treat steel a couple of years before that car was built... But the smog BS exacerbated the problem.

The biggest reason manufacturers went to roller lifters, was the removal of ZDPP (often refered to as "zinc") from motor oils. It was supposed that the zinc might contaminate a catalytic convertor. Nothing supports this, but the ZDPP is gone anyway. ZDPP is a high pressure additive, and is cruical to the proper break-in of flat lifter camshafts.

Heavy duty diesel oils still contain zinc. Oils like Rotella T, Delo 400, and others that meet the same standards. Additional zinc should be added to a new engine build - the best source is GM EOS or Engine Oil Supplement, available at the GM parts counter. Use the whole can on a fresh engine, and be sure to use either more EOS or ZDPP containing oils when you change the oil.

Camshaft break-in on a stock engine is done any way you are comfortable. When that car was new, it saw several cold starts before you ever sat in it. I would just put it together with good oil, some EOS, and drive it normally. Change the oil at 2 to 3 thousand miles and carry on....


B.

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

mhamilton on Thu December 15, 2005 1:35 PM User is offlineView users profile

Thank you!

Yes, the EOS is something I will add to my engine.

I have heard about the original soft cams from GM, and that was the reason for the original problems. But during the rebuild I put in a fresh cam. I can't imagine a new cam having the same hardening problems as one from 1980, do you attribute this second failure entirely to lack of zinc in the oil, or just lack of any formal break-in period?

Would changing over to a synthetic oil help the problem at all?

bohica2xo on Thu December 15, 2005 2:07 PM User is offline

MHamilton:

The cam failures (both of them) could probably have been prevented by having enough zinc in the oil. Companies like Comp Cams now recomend either Rotella T, or "off highway use" Valvoline racing oil - which still contains zinc.

Synthetic oils do not have any great increase in carrying capacity over regular oils - they need zinc too. If you prefer synthetic, use Rotella T synthetic as it still contains ZDPP. In fact, it actually has MORE zinc, due to the extended drain intervals. Rotella T synthetic is available at WallMart, in the standard 15W40 grade. I ran this oil in cars when I lived in northern CO, year round. Never had an oil related problem, and my '86 ranger went 325,000 miles without anything more than a couple of timing belts.

If you live someplace so cold that 15w40 won't work, go the EOS route...

Good Luck.


B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

mhamilton on Thu December 15, 2005 5:58 PM User is offlineView users profile

I have always used Valvoline 15W40, I have no desire to use synthetic. Once I get past a couple oil changes with the EOS, do I keep using that, or will it be okay with regular oil?

Thanks again for all the help, as soon as I have time I will pull the valve covers and intake to see what I have left of a valvetrain...

-Michael

HerkyJim on Thu December 15, 2005 6:17 PM User is offline

As I understand it, you need to operate the engine at high enough speed to ensure good lubrication of the cam lifter contact. For cooling and friction reduction. The hot rodders seem to be having lots of trouble with the quality of the parts these days, but they run heavier springs and more aggressive lift profiles. In any case, its not a good idea to be cranking for a long time or to let it idle either. Good idea about the HD oils. I use Delo or Rotella or Wallyworld 15-40 whatevers on sale or cheaper in my 60s and 70s cars. Some people say that doing that in cat converter cars will lead to shorter cc life.

clueless on Thu December 15, 2005 7:55 PM User is offline

Chevy cam break in and wear issues have been around for a lot longer than the missing zinc in oils. While the zinc additive is good advice there is more to it.

Just curious how could zinc in oil destroy a cat? If your burning that much oil it will destroy the cat anyway.

HerkyJim on Fri December 16, 2005 1:49 AM User is offline

"...Just curious how could zinc in oil destroy a cat?..."

Did I say that? Nah. I've heard that about reducing the service life of the item though...

HECAT on Fri December 16, 2005 10:29 AM User is offline

Just to weigh in with a relevant story;

80 Camaro w/ 229 V-6. At 80,0000 miles it lost power, rough idle, etc. After checking ignition and fuel I removed the valve covers and started the engine more rockers were not moving than were and I could not believe the thing would run. Removed the cam to find 12 of 16 lobes to be round. I thought GM had figured out the heat treating process for cam lobes in the 40's

Got a Crane mild performance bump stick, new lifters, timing chain, fresh oil & filter. Pumped up the lifters with prelube using a old hand pump oil can. Set valve lash according to spec with everything cold, engine not running. Started engine and let it run on choke high idle for 20 minutes. Still running today with 250,000 miles. Where did the lobe material go and why did it not wipe out the rod and main bearings? All I can say is the filter must work pretty good.

My thought for this posters situation is that not setting the lash cold but rather starting the engine to run the valves may have allowed the lifters to pump up only to find the lash set too tight and wiped out the lifters or the new cam lobes. Is Dad an old Ford guy? My Ford friend (drinking my beer and supervising the cam install) told me to run the valves with the engine running but I chose to follow cam manufacturers instructions.

My Method for performance cam break in: I build my own 327 cu. in. small block Chevy racing engines for my drag car. I learned from old stock car guys to build them loose and run them hard. Set everything cold and breaking in occurs as it idles in and out of the trailer and to the staging lanes. Then it is in the burnout box at 6000 RPM followed by a run with shift points set at 9000 RPM. I loosen the load on the springs when parked for winter and reset cold in the spring. Motors last 2-5 seasons before they come apart and never due to a cam failure. Just my 2 cents.

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

mhamilton on Fri December 16, 2005 11:19 AM User is offlineView users profile

HECAT,

I have heard from a guy who works for GM that the cam manufacturing process changed, and the hardening process did not penetrate deep enough into the metal for proper wear. I can't say for sure why a 2nd cam would go, but I'm hoping that the filter caught the missing cam lobes.

Dad is actually an old Chevy guy, but will never hear of using a factory shop manual to build an engine. His method of valve lash worked in 1960 on a 283, so it should work on a 25 year old 1980 6 cylinder small block... or something like that

bohica2xo on Fri December 16, 2005 1:45 PM User is offline

MHamilton:

Unfortunately, the zinc is still needed after break in - if you want the best life from the cam & lifters. On a flat tappet cam, the contact area on the nose of the lobe is very small, and the force can easily exceed the film strength of the oil. This is why the EP additives are needed, so that the two metal parts do not begin to develop microscopic friction welds, and start shedding metal. This is mitigated somewhat by the burnishing that takes place during break-in, but can still be a problem depending on the specfic metallurgy at hand.

It looks like you will be doing a cam replacement. Since you have lost some lobes, be sure to do an oil change, and while the cam is out, run the oil pump by hand for several minutes. This will flush the oil through the filter, without spinning the crank. You should be fine - the junk created by the lobes is basically dust.




HerkyJim:

While adding oil flow does help cool the camshaft / lifter interface, the problem is still the EP quality of the oil.
Think of the "birth" of a factory car in the pre-catalyst days. It was assembled, then driven a short distance to rail or truck transport. Started again & again for short moves, finally parked at the dealership. It MAY have been run for 15 minutes or so at idle during the PDI. It may have been driven around the block (hard) and shut off.... You get the idea. Interestingly enough, most of those cars had a fairly long life, even with all of the excess fuel the carbs provided in those pre-catalyst days.

As for the ZDPP harming a convertor - hogwash. Just like the R12 mess, the EPA went way overboard. The zinc is present as a salt, and in small quantities. As Clueless said, if you are burning enough oil to compromise the catalyst, you have larger issues...



Clueless:

The biggest single problem with flat tappet camshaft assemblies today is the loss of EP additives like zinc. Sure, finish and heat treatment plays a part - and over the years some manufacturers have changed heat treat processes (or had bad batches), but the big change is the loss of the EP additives. If you chart the camshaft / lifter failures over time, you can see the zinc dissappear.

I know more than a little about this. My degree says Metallurgy, and my resume lists one of the larger lifter manufacturers. We have a dynomometer that is specifically built to test cams & lifters. There are several things that determine the life of a cam assembly. Most of them the consumer has no control over - metallurgy / heat treat / finish.... but the consumer does control the springs used, and the oil. On a more or less stock engine, the oil is the biggest life determining factor you can easily manipulate.

If you want more life from the camshaft, certain things can be done. A heat treating process called Salt Bath Nitriding can be applied. This will bring the surface hardness of the treated parts up to Rc70 or so, while improving lubricity. The finish can be refined before heat treat by polishing, and during heat treat by using the QPQ process.

Some specialty camshaft manufacturers (schnieder comes to mind) still "Parkerize" their camshafts. This helps during break-in, by depositing a layer of zinc phosphate on the lobes of the camshaft. While this eventually wears off, it allows for proper burnishing of the interface. Other manufacturers use various "solid film lubes" - which are things like moly sulfide bonded to the surface with a melamine resin. All of these treatments are temporary, and only enough to get the surfaces burnished, with the HOPE that the finish improvement & work hardening will be enough to make the cam last.

Another manufacturer (schubeck) has developed a ceramic faced lifter, that shows promise. By using a lifter face that is not metal (and bloody HARD), there is no chance of microscopic welds forming at the lobe interface. The ceramic material does not wear, and the lobe burnishes quickly - the down side is the cost. Those lifters are expensive right now, and I doubt there will be any use by the big 3 - so the volume will remain small (and the price high).



B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

mhamilton on Fri December 16, 2005 5:16 PM User is offlineView users profile

See, I knew this was the right place to ask my question!

So far I've only had time to pull off the driver side valve cover. The adjustment nuts are not even, some look like they're at least 1 turn lower than the others. A couple of the rockers have play side to side (well, play around the stud), and those pushrods are wearing on the head casting. Definitely have to take care of that problem. Over the weekend I will pull the intake and get a look at the cam.

clueless on Fri December 16, 2005 5:19 PM User is offline

Bohica

Very informative post. Thanks.

You still seem to miss one important empirical piece of data. There are plenty of engines that ran only EPA neutered oil that have very high mileage. If the zinc is a major factor why do these engines last as long as they do?

bohica2xo on Sat December 17, 2005 3:14 AM User is offline

Clueless:

Many of those engines you speak of have plenty of camshaft damage - they still run, but since they were doggy smog motors to start with nobody noticed half of the lift has gone missing....

Some of course are merely statistical outliers. A just hard enough cam, mated to some decent lifters that managed a good burnish during the first minutes of running. The fact that the failure rate took an exponential climb as ZDPP was phased out is the important part of the data. There were only a few years between "no zinc" and "roller lifters" across the board. Those years were the most obvious - that and the "new" problems in the hot rod world with killing flat tappet cams.

I can't disclose the names of the cam & lifter companies that get crates of metal parts from India. Lifters made from old bed frames, carburized so that they are hard on the surface..... Sort of like chinese stroker crankshafts that are machined in an CA beach city, you never really know what you are getting. If you build high performance engines for a living, I would invest in a decent hardness tester.


B.

.


-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

mhamilton on Sat December 17, 2005 5:10 PM User is offlineView users profile

Today I pulled the intake, the rocker arms, pushrods, and the lifters. Even though it never had any formal break-in, the lobes are just fine, and the lifters are perfect on the bottom. The tips of the lobes have a little wear, just visually smoother looking than the other parts of the cam, but all measure the same. Otherwise the cam looks like new. And all that with my father's method of adjusting valve lash while it idled brand new! (although I will break in the new valve train parts per GM specs).

Chick, I must say that you were right about break-in while driving it normally... although I didn't use kid gloves the first 500 miles, I just punched the gas right to the floor It seems that this cam survived.

Even though the cam is good, I am replacing everything else in the valve train. New lifters in case one of them was defective, and I'm going to replace the original pushrods, rocker arms, rocker balls, and lock nuts. Half of my lock nuts had no torque left in them, that's a likely cause for my lash problems. And the rocker arms have considerable wear on the tips, I think they might have been causing quite a bit of the clicking.

Well, I'll see what happens when I get the engine back together. I expect it to hum like a sewing machine!

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