Technical Flat tappet cam failures

Had a new Crane cam fail [327 chev] after about 20 minutes...sent me a new one and it was fine. Had a bunch of stock chevy cams go flat over the years, most notably my old 72 nova 307. Lobes were almost round!

 

Right around 2007 when oils changed, had a Pontiac round a couple of lobes. Engine had plenty of miles on it, then oils changed, and once the fellow heard the rocker arm tick, it wasn't but just a few miles before it rounded all the way off.
I blamed the oil change, been using good race oils ever since with no problems.

joe

 

My 326 Pontiac rounded the lobes with old oil formulation in 1977, and 440 Plymouth did the same in 1981.

The manufacturers moved to rollers at least partially because of cam failures with mild OEM grinds, well before any oil formulation changes. Performance grinds have higher acceleration rates, so hertz stresses will be higher and wear worse.

Flat tappet cams are obsolete technology.

 

I lost a solid flat tappet cam in my BBC in 2006 or so. It was a Crane Blueprint series LS6 cam. Metal all through the engine, really bad. The only parts I was able to re-use were the bare block and heads. Went roller at that point and swore I'd never run another flat tappet cam.

In talking with my favorite machinist a couple of years ago, he indicated to me that he started seeing cam failures after OEMs went away from using flat tappets, so the only market for them was the aftermarket, and cores went overseas. Lacking the quality cores, many more failures became common.

With this information, my son and I recently built a 283 for his car, using a cam I bought new in about 1991, ran, then pulled and still had sitting on the shelf. Broke it in with new lifters, assembly lube on it and regular Chevron 10w30 oil. Has about 500 miles on it so far, runs great. 262/268 solid Crower with Z28 springs on 305 heads.

I have another small block I'm putting together, an early 327 Corvette motor, yes it really is, and causing me problems for that, but anyway, using a new Howards hyd flat tappet cam that I'm a whole lot more nervous about breaking in. Just don't have the cash to go roller on this one.

Devin

 

I guess I neglected to mention that the engines I was running didn't come "on cam" until just under 3000 rpm... built for h/p at 6000 rpm was very lumpy under 28 - 2900 rpm. my bad, in a stocker or street engine I agree 2000 to 2200 sounds good - cheers

 

'Built a SBF in 2007 with a Comp 268H and Melling lifters. Springs were new Comp High Energy. 'Used the cam lube (that comes with the cam) on the lobes, and assembly lube (don't remember the brand, but it's clear and thick as molasses) on the lifter faces.
Engine oil was Motorcraft (made by Valvoline) 5w-30. I didn't know about ZDDP additives back then, so none was used. 'Ran it at 2000 RPM for the first 10 minutes, and then varied between 1500 & 2500 for the next 10. A little over 3000 miles and so far, no problems.
I now add a bottle of Comp Cams break-in lube with each oil change...

 

my freinds have had cam failures from one company and even some solid rollers too , and I do not use that manufactuer they seem to have a QC problems and tell the customer tough luck when it comes to failures even when following there directions , I never had problems with Elgin , Mellings, Crane and Howards , but most of my newer builds are roller cams only, this way no way of a customer using non ZDDP oil and wiping one out .

 

OK I was also ASE Master tech and ASE Master Auto Machinist before retiring so we are talking man to man. First you didn't do anything wrong. PSE know that. Oils are not what they used to be and I suspect lifters are not either. I have gone in extreme situations like the little bugger to the left to having the cams nitrided, a service offered by Comp Cams by the way for approx. $100. That has proved to be the best solution as because I am always playing with cams I get to look in after a year or so and see. Recently I stepped up a notch with the slant six and removed the nitrided cam I put in a few years ago. I just installed it in my VW Gasser engine (225 slant six .100" over) about a month ago and I should have taken a photo for you had I known. No wear, zero. Cam was still black except for the very crest which was just shined but not worn.
I run a lot of spring pressure for a flat tappet and my cams are beyond what is commercially available so it isn't like a mild street type thing. I get them made to my specs. I am convinced beyond any doubt that the nitriding is worth every nickel spent. How did I discover this? I knew about nitriding from my 426 hemi days but had not heard of it for cams. I had a hunch it would work and went on the net looking for applications. I discovered VW air cooled guys have been doing it for years with great success. Then I discovered Comp offered the service and sure enough found it in the catalogue. Since then I started using it when possible. Some would balk at the extra $100 (and the extra order time as they are done on batches) however if you lose a cam that is nothing and you won't if it is nitrided. I feel your pain BTW as I also cared very much about my professional reputation. Is that worth a hundred bucks? Certainly, no question about it.
Don

 

No failues (knock on wood) , i use vr-1 oil on my solid flat tappet. I used gm eos during break in. . If I was putting in a new cam I would use the Crower cool face lifters with the oil hole on the bottom of the lifters and pay attention to spring pressures.

 

I'm confused. The whole "wear-in" process is about having the parts get to know each other by shaving some material off each other until they're happy in their new life together. My new cam had a rough lobe surface that I imagine was left rough so that there was friction between the lobe and the lifter to encourage the wear-in.

Nitride hardening is a really thin layer which leads to some questions:

1. Wouldn't the hardness of the nitride prevent wear-in?
2. If not, wouldn't the wear-in remove the hardened nitride layer?
3. Wouldn't nitriding be better suited to roller cams?

 

Even though my roadster with sbc is primarily a street cruiser with very little drag racing, I wanted a fairly radical cam for sound So I picked a Comp Cam grind with 230*i-236*e @.050 lift and .488i&.505e lift and the recommended springs. I went with the solid lifter version so that I could use the trick lifters with the .012" hole in the face for oiling. That won't work with hyd. lifters.
Reasoning that having 16 more oil bleed off points, I also used a high volume oil pump.
Used liberal amounts of CC's assy. lube on lifters and cam, Joe Gibbs break in oil, used the 2000 rpm break in procedure as mentioned above, and after driving for a bit, changed to Amsoil filter and Amsoil Prem. Protection synthetic 10-W-40 oil with a high ZDDP content.
Oil pressure is around 40-50 hot at cruisinf speeds and 35 or so @ idle now after about a year. I'm happy with the whole setup.

 

Would ifs I know nothing about. I do know from personal experience over 45 years or so this is by far the best solution I have found. when I said no wear I meant no wear. Not not much wear, not pretty decent condition but No visable wear of any kind. here is nothing more I can say. It is a sure cure.
The rest is up to you. I run the fastest rise lobes available for the 904 mopar lifter with the high spring pressures such and "active" cam requires. You can't even buy these cams off the shelf.If any cam had an excuse to fail this would be it. So while you guys are mixing your magic elixars and still having problems I am running down the rack smiling. I have had several done both for my six and other V8 builds as well.
There is the trough. Drink or don't, tis up to you.
don

 

1. no its a very hard surface and other material is of the same hardness so the surfaces would polish each other to a smooth surface .

2. no , as only soft materials would wear off , the only way the nitriding would wear is if the material that rode on it was harder like carbide and this is a sliding action not a stationary one the lifters are supposed to rotate to change the wear surface as its moving to prevent heat build up and galling .

3. no a roller cam sees less surface pressure in the area of the face of the roller vs the area the tappet would see and the roller prevents the heat build up as its rolling along the surface instead of sliding on it ( think of a tappet as dragging a cabinet across the floor top side down , and a roller as putting it on a dolly ) . plus the pressures are a larger surface compaired to a tappet and the ramps are easier to climb due to the rollers large radius . nitriding would make the surface more brittle and might cause spalling or cracking on the face. you want a roller cam to be strong because of the spring pressure but not brittle , think of nitiriding like a diamond . strong but can be shattered if pressure put on it wrong .

 

This is the way I see it too. Cams and lifters are hardened and need to be nearly the same hardness. The cams that others have shown me or that I've seen pictures of have one or 2 lobes that have worn down. If the oil or break in procedure is the problem, all of the lobes should be worn. It's much more likely that the cause is a cam lobe that isn't properly hardened or a lifter that is not compatible with the cam.

 

Had a couple of new box stock 1986 350 Chev 3/4 ton trucks wipe cams early in warranty. I had another small block 350 Chev with a flat tappet wipe a cam on the first break in cruise. I replaced it with a roller.

 

There are a few common reasons that just one or two lobes are first to go flat. When turning the engine over by hand any visible resistance of the lifter spinning in the bore should be investigated and remedied. Also it was pretty common in the past to see 5-10% variations in valve spring pressures. It use to take a couple of sets to get an acceptable match for installation

 

I think a lot of this failure rate has to do with the EPA and manufacturing emissions and trying to keep costs of manufacturing down as , I have some old NOS Pontiac cams ( mellings) from the 70's in the tubes still and they look different they look more metallic vs dull on the lobes and smoother surfaced ( . I know when we sent a cam that failed from one aftermarket manufacturer to the metal lab we found the face to be real thin less than (.005 ) of the heat treat they use compaired to the old oem cams ( which was .010 + and the hardness was almost like it was not carburized . but just put into a oven and heat treated .

 

the lifter bore is one of the most overlooked things when rebuilding a engine or recamming , people spend time to protect the cylinder bores but often do not protect the lifter bores and they are more critical and it only takes a little pitting to make it rough enough to stop the important spinning of the lifter .the spinning stops one spot gets hot the surface then fails and then it will act like a machine tool and start cutting .

 

As I understand it they took the Zinc out of oil because it was causing premature catalytic converter failure. EPA SUCKS!

 

Just went through all that. Don't know who's cam was installed by my engine builder but all but three lobes were wiped out. I can't believe it ran! It even sounded good but every time I put it in gear it stalled. After adjusting the valves three or four times in the first few hours of running I finally smartened up and pulled the cam out - looked like a roller cam except for the three lobes. It was broke in right too. Now, after pulling everything apart, washing everything and and installing new bearings and a Comp cam, it runs great. Just in time for the season to be over. Pisses ya off.

 

By the late 70's the bad Chevy cams were well know. Pontiac also had their problems. Even IHC 345's had some bad cams in the 70's.
The worst I remember the the early 70's Pinto 2000cc OHC engines. Very few to none made 25,000 miles on the original cams

 

Kind of a bitch they set it up like that .

Yes we have cams, any kind of cam you want too.
Ooh you want a cam that's not going to go flat? That will be 100.00 extra
Now please see Hellen , yes go to Hellen Wait while we fix you a cam.

 

I have the exact same cam and lifters. No problems so far.


Posted using the Full Custom H.A.M.B. App!

 

At least on a Chrysler you need to make sure the lifters rotate turning the engine by hand before firing it up. It'll eat the lifter if one or more don't rotate.

 

And some aftermarket lifters are too snug. I have run into that a couple of times during an engine build and usually junk them for my favorite brand.
I understand your frustration hemi with the concept it takes an extra hundred to get a cam that won't die. They could probably cut the price in half if the did all cams as a matter of course however the bottomline is I am responsible for the motors I build. If the cam fails no one will care who made it they will blame me and so a hundred bucks to insure it was never a problem was a no brainer for me. And for my own engine I was happy to pay it knowing I wouldn't be trying to pull cupped lifters, and disassembling a new engine to get the crap out of it. So yes perhaps taint right but tis practical. My Mother, former 1940s Flt Sgt "Danny" taught me almost from birth "An ounce of prevention is worth a pound of cure " and for some reason it stuck with me long after she departed.
don

 

I've bought "shot" SBC engines with flat lobes, minimal miles...Dirt cheap!
The right cam and lifters, total disassembly, close check, zinc additive and 283 spring break-in...
Wow! Another SBC sold, $2K the easy way...

 

I hear you Don and I could not agree more. My thinking is the cam manufactures should think the same way. "Failure is not an option for our cams" is what the should think. But, what they've done is given us an option to help insure they won't. In other words, they sell junk and know it.

 

Well, I dropped my block off at the shop yesterday. Dropped the crank, rods, pistons, flywheel, clutch, pressure plate, and balancer off to have the balance checked (why not just do it all from the get go, again)

Luckily the machine shop (who machined the block in 2012 when I originally built it) isn't bending me over trying to double charge on a lot of stuff. So the block is getting inspected, cleaned, new cam bearings. I will clean it again and repaint it. I have a new cam set coming. Comp k35-425-8 (pretty sure that's the part number, off the top of my head) Its a 351W cam so the firing order will change. I will be swapping the eddy RPM springs and putting the springs in that cam with the cam, I will have to remeasure for new pushrods due to going with a roller cam. I have all new Felpro gaskets (again), new Clevite M77 bearings. New FRPP cam thrust bearing retainer, I need to buy a thrust bearing and main bearing kit still. That will be tonight.

 

I think more of there philosphy (sic) is its not used as a DD anymore just as a low milage special occassion vehicle so they do not have to put the quality into it like they used too . when I order a cam If I had to spend $100 more to make it last thats on the edge of a custom roller , the only expense then is the lifters and springs and the performance is far better . ( even a stock style grind in a roller is more responsive due to the ramp speeds )

 

So, , since I am redoing it all......

Would you guys do a stock replacement oil pump or a high volume pump?