Zinc and flat camshaft lobes

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Truckedup

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I searched and found some info here on zinc in motor oils,I have an experience to share,I'm a new guy so bear with me
I have an old Chevy truck powered by a heavily modified 1950's 302 GMC 6.The performance cam lost a few lobes after about 1000 miles.I tore into the engine,yup,2 lobes galled badly.
Talking to several aftermarket cam grinders and engine builders,they all pointed to the lowered zinc levels in oil.They all had the same story,flat tappet cams,mostly used in older OHV American engines suddenly had problems,where they had none before the zinc reduction.We're talkin performance cams and stronger valve springs.
All the people I spoke to suggested using a pint of GM assembly lube poured directly into the crankcase along with brand name Diesel 15-40 oil for initial cam start up and then either 15-40 Diesel or Valvoline ZR conventional racing oil,the Valvoline appears to have more zinc than most any other oil.
I've read,that during the first 5 minutes of life,a flat tappet cam and lifter may have as little as .003 inch contact surface.With all the spring pressure pushing down on that dot,maxiumum protection is needed.
So,I have bottle of GM lube,Diesel and Valvoline oil,not gonna repeat the bad cam problem........
 
My little 4-banger Hyundai has, so I'm told (How would I know?), flat tappets to actuate the valves, but they also say my valves will open against the springs with a push from one little pinkie.

Do I need zinc? Or is my VSOT add giving me that?
 
It all sounds like a satifactory set-up for the time of original manufacture. Just how equal are the test regimins run today representative of the conditions of practices and specs that worked decades ago??? I gather they don't cater testing with much consideration to special vehicles, er engines...antiques. Perhaps it just doesn't seem worth the time and further expense, and perhaps some may feel it's better that such dated technology best be out of service?

Granted, the case in point is pertaining to aftermarket products and with different operating perameters. Special set-ups require special treatment and thus of course greater knowledge. Maybe to, such cam manufacturer's should step-up to meet the durability of OE's longevity for such situations of spring tension, or list recommended limits on such so as to not enable someone to put products in conditions that would be out-of-spec. and the operator not knowing there running a risk. I mean, just what kind of "wear-in" do OEM's do on all they engine's they build day-in and day-out anyhow? Could running anything aftermarket just come to mean one's playing with fire?

Sorry to hear of a scrapped cam, but perhaps you're in a better position to deal with your new engine set-up for the long haul. Good luck!


What could this all mean for technology that's but a decade old
dunno.gif
...needless to say I'll be keeping an eye on UOA's.

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I believe that flat-tappet cams will need additives like SX-UP from Speciality Formulations or Valvolines VSOT for any dino now including Diesel Oil.

Even diesels are now having the Cats OEM installed now. So extreme pressure additives must be added for flat tappet cams.

Not unless you want to run a synthetic oil!

CuriousKid is Right, the way of OLDIRON is being phased out...with gas and oil products,some would say "rightly so" others would say "there is room for both."
 
I agree with has been stated. I think that the HDEO oils will be around in their current form for a while yet, because demand will be there for them.

The additives that are currently available, I'm sure will be joined by NEW additions for supplimenting the new demand for strengthening these new oils, for our old iron.
 
I have a 351C4V in my restored 1970 Mach 1 but didn't rebuild the motor myself. I used Kendall GT-1 for the first 5000 miles or so without any issues and now use Redline 10/30. That is to say I don't think that I have a damaged cam as it runs great and is free of any valve train noises. What led you to the tear down initially? You would think that if it was an oil related issue you'd of had more than 2 lobes damaged in a thousand miles.


As you said good lubrication at first firing is critical to a good cam break-in and so do you think that there was any chance that those 2 lobes had too little break-in lube or were the valves a little too tight? Maybe you just had a bum camshaft out of the box. I agree with you on the diesel recommended oils as a good choice for a flat tappet engine but would go with a lighter weight than the 15/40 until your motor loosens up.
 
I have used GM Engine Oil Supplement as an assembly lube, especially pouring it directly on the cam lobes and dipping the lifters in it.

LargeCarMan,

How is synthetic alone going to make any difference? The SM formulations have the same Phosphorus limit.
 
I've been concerned about this issue myself. I have an older Chevy PU with a relativity new GM 350 replacement crate engine. I don't know what oil to use in a non-roller engine.
 
Jimbo, I suscribe to the idea that synthetics film strength/sheer strength acts like a barrier that additives like zinc do. I know some don't like the 4 ball test, but examples of synthetic vs. dino have proven synthetics are superior in film strength. I like the synthetics that are still rated SL for old muscle in the 10-40 range.
 
I would just like to note that I'm not trying to spark anxiety in those who care about lubrication/engines, but as I to have a flat tappet cam arrangement, have written based on some of my own concerns. For what little I know in the way of chemical interations, polar attractions, molecular shear strengths, etc...I have admitted to myself the reality that I JUST DON"T KNOW. With my background it would seem obvious, but it's easy to get carried away with the facinating world that presents itself in a machine such as the internal combustion engine.
 
Ummm... I don't know. There are plenty of flat tappet cams out there doing just fine with current oils. How was your cam heat treated? What about the tappet grind, flat or convex? Did the tappet grind match the cam? It seems much more likely that the cam/valve components are not harmonious or have poor heat treatments. This was a major problem 15 years ago when all oils had plenty of zinc. I have to say it is very unlikely that oil caused this problem.The components are to blame.
 
Carock,absolutely,it could have been mechanical components,and aftermarket cam grinders may find it easier to blame lubricants for problems than the parts they make. Camshafts are hardened before grinding,the most commonly used cast cams are hardened to the core.Cast cams are supposed to be used with hardenable iron lifters,steel forged cams use chilled iron lifter.With an old engine like my GMC,you're on your own with valvetrain components,everything ya buy is suspect
wink.gif
The cam that went bad is cast,was reground by a reputable shop,used brand new hardenable iron lifters,followed cam breakin procedures to the letter and then some.This isn't my first cam installation in these type engines, but it is the first failure.
SM oils? The Valvoline VR conventional racing oil is SM rated,says on the container it has increased levels of Zddp to prevent scuffing.
 
Only the "energy conserving", that is 5W-20, 5W-30 and 10W-30 grades of SL and SM have the phosphorus limit. So, blenders are free to add as much ZDDP as they wish to 30, 40, 20W-50, etc.

Lycoming had such a cam and lifter wear issue in some light aircraft engines that they require a phosphorus-based additive. "Ashless dispersant" oils otherwise contain no AW additives.
 
Jimbo,Valvoline racing oils have ashless detergents,what is AW additives.
I just had another camshaft reground by a different shop.he called me to say the NOS stock cam I sent for reworking has no taper to the lobe tips,and if the other cam was ground falt,it may be the cause of early failure.The lack of lobe taper was probably ok for low speed engines with weak valve springs.The lifters I'm using have a slightly covex surface.
This cam wear problem is pretty much only on high lift performace cams with springs in the neighborhood of 250 lbs of open pressure.
 
My only comment in this thread would be to add that any good modern HDEO will have plenty of P, Zn, Ca, etc to protect the cam lobes. They really don't have less antiwear additives or antiwear properties than oils in the 1960's........in fact I would wager these oils actually protect better.

Feel free to add the goodies mentioned, but only a UOA will tell the story (well other than tear down and measuring)
 
I went roller in my Pontiac..... how nice not to have to do a 20-30 minute break-in and worry about a lobe going flat. That and the power. "Once you go roller you never go back". Sure it's more $$$ initially but once you lose a cam the roller sure looks good.

HDEOs is what I used when I ran a flat tappet, Delo 15w40 worked out great. Cam & lifters always looked real good.
 
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