Flat tappet lifters, wear patterns, cam lobe taper and other things. Let's swap opinions and ideas.

[Kern Dog]

Most of us have heard of how engines with flat tappet camshafts have had increased failures in the past 15-20 years. There are a bunch of opinions on what is to blame but so far, I have seen no 100% smoking gun on the exact cause. The potential causes are numerous.
Reduced zinc in oil.
Camshafts and lifters made with softer metal than before.
Lower quality machining from Chinese factories.
Lifters that don't spin in the bores.
Valvesprings too stiff.
Improper break in.
Etc, etc....
While all of those things may be true AND if you have more than one of those situations together, the chances of a failure seem to grow exponentially.
I know that there are several threads on this site covering this topic, I was hoping to expand a bit on what has already been mentioned.
Being one with a curious mind, I wonder about a few things...
We have been told that with flat tappet systems, the lifters mate to the lobes. How? I've read that they establish a pattern to each other and that to swap in another lifter, it must be NEW and that the "break in" starts all over for that lifter.
Why? Has anyone ever published pictures and measurements of the actual wear patterns?
Who remembers Jim LaRoy/IQ52 ? he mentioned before that he has swapped lifters around and even reused them in dyno testing and had no failures. How is this possible?
I remember a buddy going out to the junkyard and pulling a couple lifters from an engine to swap into his engine. He had a couple sticky lifters in an old beater. I don't recall any future troubles that he had.
I did the same to a stock 318 years ago.

 

[Kern Dog]

In the red car, I started out with the famous/infamous 292/509.

This was my first Mopar big block. I had experience with Chevy 350s prior to this but Mopar engines were new so I was learning as I went. I wasn't on any car forums so what I learned was from magazine articles and word of mouth chatter. Back in 2001, I hadn't heard about how common that cam and lifter failures were. I didn't know about oil quality. I barely knew about tuning an engine aside from parts replacement. I had the infamous Mopar Performance electronic ignition conversion including the distributor with that crazy long 28 degrees of mechanical advance. I didn't know about limiting advance to allow a lot of advance at idle (for better idle quality and more pep) without pushing 44 degrees at 2000 rpms. I chose the 509 cam because it was the biggest hydraulic that MP had and it was available at Summit Racing. The car idled rough, was sluggish off the line and detonated at higher rpms. The fix? replace the antique 509 cam with a new design!
The Comp Cams XE285HL was a fast rate-of-lift design and high lift...

I used stock rocker arms with a .545 lift cam. Some will argue that I messed up there. I've read that the fast rate-of-lift cams are aggressive and are more prone to eating lifters. I don't know enough to say that is true or not. I don't think that I even thought about changing the valvesprings. Some people get on these forums and scream how Comp Cams are the worst. To that, I argue that since they have over 50% of the market of valvetrain products, they will have more failures but also more success stories. It is a simple numbers game. What really matters is the percentage of failures. Maybe they have a lower or higher rate of failures? Who knows? Nobody that I know of has compiled all the data to do a study and nobody ever will.
In retrospect, those cams of mine were destined to fail and not because of any defect in manufacturing.
The 509 didn't fail despite similar stupidity on my part. Maybe I was lucky? After the second Comp Cam went flat, I slipped the 509 back in. It was fine until I pulled it a few years later. Why did the 509 cam survive and the Comp Cams both fail? Was it because of the low lift and lazy ramps? I pulled the engine in 2011 for a refresh of new rings, bearings and gaskets and put the 509 back in...but then tried a wild Lunati cam while under the mistaken impression that a bigger cam will kill cylinder pressure and reduce detonation.
In 2022 I had a MP '528 solid in the engine. It ran fine for several years, thousands of miles and several long distance trips. Right after the Spring Fling show in 2022, the dang thing started misfiring and the valve lash got much bigger on several lobes. The diagnosis? Several lifters and lobes were failing. The only thing that I did that I can trace the blame back to was a change in the oil a few months prior. I went from using Valvoline VR-1 to a modern synthetic that claimed to have extra ZDDP.
I pulled the engine, bored it another .010 over to .040 and put the Lunati back in. I knew that the cam was bigger than ideal but my cheap tendencies got the better of me. I contemplated a roller cam to get around the risk of failures but the cost to make the leap was just too much for me to accept.

 

[Kern Dog]

The reason/reasons for cam and lifter failures are still a mystery to me, like an itch that I can't scratch.
Why is it that of all the stock, medium performance engines that I have had, NONE of them have ever wiped a cam?
Isn't the oil to blame for failures?
I currently have 5 classic vehicles out back with flat tappet cams. These two cars are build a bit hotter than stock:

To add, I also have a 67 Dart with a 360, a 72 Duster with a 360 and the 75 Power Wagon with a 440. I have not used any special oil in these three and have seen no failures.
Can we narrow the failure risk down to the higher performance engines? If so, what specifically increases the risk of failure?
I've considered that the stiffer springs may put a greater load on the cam and lifter interface. Maybe the greater pressures overwhelm the oil film and if the oil isn't up to the task, rapid wear starts to occur?
We have been told that on first fire, the engine MUST start right away because the longer that you crank it, the assembly lube goes away and you're just at metal to metal at every point. Even so, I've had engines of medium and high performance have problems starting and still have mixed results with success or failures later. To me, this muddies the waters and proves nothing. Extended cranking has occurred in engines that both lived and that failed.
I've started a few threads here about camshafts and lifters. One was the following:

Who has NEVER had a cam or lifter go bad?

I was surprised that so few members reported failures. I've heard about the rise in failures from a variety of places but when I started that thread, the failures just didn't seem as common as I thought or people just didn't feel compelled to post about it.
Part of the reason that I started THIS thread is that I am considering another cam swap for my 440/495. I've asked around about roller cams and once again, the sticker shock feels like a punch to the face. I'd easily spend $2000 to do this considering the different parts I'd need to buy and change to do it. I don't mean to be a cheapskate but I often factor in the value of an expense. Yes, there are reassurance that failures are far lower with a roller setup but at the same time, I've heard of how noisy these can be. I'm already tired of the clickity clack of the solid lifter setup that I have now so I'm interested in a change back to a hydraulic to quiet it down a bit.
Yeah...I know some will call me a hypocrite. I've teased some guys that posted here asking about how to eliminate the raw gasoline smell from their cars. I wrote about how MEN like the smell of gas and now here I am looking to quiet down a classic hot rod with 2 inch headers.
I've read lately about how some people have started going back to OEM hydraulic lifters after having them refaced by a professional.
This lit a spark in me. It seems like it could be a workaround for the problem of cam and lifter failures.
Think about this: You'd be using a genuine OEM quality part that has a proven record of durability. It would be machined to have the proper crown for adequate rotation. Right there you eliminate TWO risks of failure. Add to that the proper oil, make sure the lifters DO spin in the bores, make sure it starts immediately and you have eliminated almost all of the causes for failure.
Am I wrong? Please chime in with your opinions.

 

[493 Mike]

The worst issue I had was the lifter bores not being in the correct spots. It caused edge chipping on the tappets (solid), which I caught early as I lost the tip of that pushrod. I had a Hughes cam and kit so I called and spoke to Dave and he recommended I send him the cam for diagnoses. As he told me the misalignment of bores was my problem. With the mild OEM cam specs the system worked for years but, the higher lift and duration cam brought out the issue of alignment. I had the bores brass bushed (with a small slot for oiling-in case a lifter left the bore) and machined the bushings to correct positions. Problem solved.
Hughes related that as the BB engine production neared the end, the machinery used to bore the lifter holes probably got worn and wasn't replaced, due to costs, resulting in less than optimal dimensions
Mike

 

[Doorkicker]

This is going to be a very interesting thread!! Thanks Kern Dog for kicking it off.

All I want to add at this point is something I haven't seen discussed often here... or maybe I wasn't looking... who knows. Anyway...

One of the reasons flat lifters spin is a result of the relative angle of the cam bore to the lifter valley. These are not perfectly aligned. If they were, the lifter wouldn't spin, or at least not at a meaningful rate. The difference is small... 0.005 from timing chain to rear plug, but it is enough to put a slight increase of pressure on the lateral edge of the lifter to force it to rotate as the cam rotates. Since they are in constant contact and both rotating, and the cam isn't going to move, the lifter rotates creating a constant orbit and ensuring the tappet doesn't overly wear in one place.

Basically, here's what I'm getting to. Have you ever met that guy that has the worst luck with cams in his car? He's tried everything... and still shutters at the thought of breaking in that new rod... or just bites the bullet and goes roller.

In short, sometimes... it's just the block and as a result are more prone to cam failures.

 

[gtxrt]

one big reason is the camshaft is not ground with taper lobes. without the taper lobes the lifters will not spin in the lifter bores. some of the cam companies did not check that before leaving. you can measure the camshaft to check for taper.

 

[lewtot184]

I really believe that a good part of the problem is people. They want what a flat tappet cam was never designed to do. I blame a lot of this on Hugh's 904 lifter thing. You can't reliably push the limits with production parts . I'm one and done with the .904 lifter hype. A hydraulic tappet can't do what a solid does. A solid flat tappet can't do what a roller tappet does. Think before you buy into all the advertising/internet/magazine hype.

 

[Kern Dog]

As I lay in bed last night trying to get to sleep at an hour earlier than usual, I pondered this topic over and over, I had the following thoughts...
The cars out back that have not experienced failures do have mostly factory parts, They are either medium performance or slightly high performance with whatever technology was common at the time of their manufacture. One is a 360 with a MP resto 340 cam, another 360 has a MP 280/474, the 383 in Jigsaw has a 280/474 and the '75 truck has a mild cam of unknown specs. They all lack the aggressive ramps and high lifts that many modern cams have, traits that allow current builds to make the power that they do. In the interest of making more power, the more aggressive camshafts are pushing the limits as to what can be done while dancing close to failure. I doubt that many people built 500 horsepower 440s in the 70s without using rare and expensive roller camshafts.
I'm trying to narrow down the causes of failures to prevent future problems and to do so, I'm trying to examine what is the same and what is different.
I've driven the red Charger more than any other car and had more cams go bad. Does that mean it is the engine to blame or the miles driven have revealed weaknesses that have yet to show up in the other engines?
The red Charger is the highest performance car that I've ever had so is it the more aggressive cam designs that are to blame?
In 2022, I spoke at length to Dwayne Porter about my crappy luck. He thought that my most recent failures with the '528 cam going bad may have been directly caused by the change to this oil:

This oil may be just fine for a roller cam modern engine but the high detergent that modern oils have don't allow the ZDDP to cling to the metal and protect it.

The theory was that the ZDDP was in the oil and circulating but as fast as it touched the metal, the detergent wiped it off rendering it useless. Why would any company think that this was a good idea??

 

[snakeoil24]

The easiest item to check is lifter rotation in the bores. As too assembly lubes the factories never used them.

 

[RemCharger]

As I lay in bed last night trying to get to sleep at an hour earlier than usual, I pondered this topic over and over, I had the following thoughts...
The cars out back that have not experienced failures do have mostly factory parts, They are either medium performance or slightly high performance with whatever technology was common at the time of their manufacture. One is a 360 with a MP resto 340 cam, another 360 has a MP 280/474, the 383 in Jigsaw has a 280/474 and the '75 truck has a mild cam of unknown specs. They all lack the aggressive ramps and high lifts that many modern cams have, traits that allow current builds to make the power that they do. In the interest of making more power, the more aggressive camshafts are pushing the limits as to what can be done while dancing close to failure. I doubt that many people built 500 horsepower 440s in the 70s without using rare and expensive roller camshafts.
I'm trying to narrow down the causes of failures to prevent future problems and to do so, I'm trying to examine what is the same and what is different.
I've driven the red Charger more than any other car and had more cams go bad. Does that mean it is the engine to blame or the miles driven have revealed weaknesses that have yet to show up in the other engines?
The red Charger is the highest performance car that I've ever had so is it the more aggressive cam designs that are to blame?
In 2022, I spoke at length to Dwayne Porter about my crappy luck. He thought that my most recent failures with the '528 cam going bad may have been directly caused by the change to this oil:

View attachment 1749267

This oil may be just fine for a roller cam modern engine but the high detergent that modern oils have don't allow the ZDDP to cling to the metal and protect it.

View attachment 1749268

The theory was that the ZDDP was in the oil and circulating but as fast as it touched the metal, the detergent wiped it off rendering it useless. Why would any company think that this was a good idea??

Pretty far off topic but.... how many products do you guys use that has french on it? Is that common down there?

 

[dvw]

The cause doesn't have a magic fix. Contributing factors in no specific order: Lack of zinc in the oil, easily fixed. Poor finish on the lifter face. Can be reground if you can find a shop that has good equipment and the knowledge to do it, good luck. Cure; old stock lifters that are new. Worn lifter bores. Now this I can buy as a probable cause. Cure; bush the bores. Not enough taper on the cam. This one seems like it shouldn't be an issue. Cam company's have been grinding cams for well over 75 years. They didn't change the taper for no reason. Poor surface finish on the cam. Same answer as the last issue. That leaves us lifter bores being crooked. They are no worse now that they were when flat tappet cams were popular. They were either right or wrong when built new. Cure? Someone with high end tooling to properly locate the holes. Again personally I think this issue is far less an issue than some think. My thoughts.
Doug

 

[PRHeads]

If I’m counting it right, Kerns current BB is sporting a 3/2 ratio for cam survival.
3 wiped(2 Comps and the 528)
2 survived(509 and Lunati)

All you can do is try and stack the deck in your favor.
Don’t use the fastest lobes, only as much spring as you need, good high zinc oil, proper break in, and ……… hope for the best.

If you’re not feeling lucky…….. then it’s roller time.

 

[toolmanmike]

Wow!

 

[Kern Dog]

Pretty far off topic but.... how many products do you guys use that has french on it? Is that common down there?

On that note, I’ll add that a well trained dog can be taught to perform
Basic mathematics.

Kidding, of course.
To answer the question, it was common to buy a product that has instructions written in English, French and Spanish. I can only guess that was to cover the three most likely languages spoken here, in Canada and Mexico.

 

[Kern Dog]

If I’m counting it right, Kerns current BB is sporting a 3/2 ratio for cam survival.
3 wiped(2 Comps and the 528)
2 survived(509 and Lunati)

All you can do is try and stack the deck in your favor.
Don’t use the fastest lobes, only as much spring as you need, good high zinc oil, proper break in, and ……… hope for the best.

If you’re not feeling lucky…….. then it’s roller time.

To your first point, yeah… my record is three cams went bad and two have survived.
The problem that I have with that is that for the first two, I can’t be 100% positive about what led to the failures to prevent them from happening again. The last cam to fail had been fine for years but failed a few months after the change of oil. My bonehead logic and PRHeads experience point the finger at the oil. The valve springs must have been fine along with the lifters spinning, the hardness of the metal in the cam and the valve lash setting. This failure is the only one that I am reasonably comfortable with placing blame.
Going back to the two Comp Cams that went bad in 2006: One failed not long after break in, maybe 200-300 miles over a few months of short drives. The second one lasted longer. One of the cam break in sessions was in hot weather where the engine ran hot and boiled over requiring me to shut it down and finish the break in later after it cooled down. During that cool down, something caused another “no spark” episode and it took a few attempts to get it started again. In short, with the Comp Cams, the conditions for survival were not ideal. There were enough mistakes there to muddy the waters and make a smoking gun impossible to find. We all hope to learn from our mistakes and that is what I am trying to do here.

 

[lewtot184]

If I’m counting it right, Kerns current BB is sporting a 3/2 ratio for cam survival.
3 wiped(2 Comps and the 528)
2 survived(509 and Lunati)

All you can do is try and stack the deck in your favor.
Don’t use the fastest lobes, only as much spring as you need, good high zinc oil, proper break in, and ……… hope for the best.

If you’re not feeling lucky…….. then it’s roller time.

And then there's the bronze gear failure. I wouldn't buy a roller because of the available lobe profiles. It just sets you up for a different can of worms. This is all about going to the wrong place because we refuse to make sensible decisions. Blow big money to build the big stroker roller cammed antique and let some pimple faced creep in a supercharged Mustang knock your windshield, with air on. It's all nonsense.

 

[Kern Dog]

Ha ha.
I’m not interested in being faster than other people. I just want the car to be fast enough to scare me a bit.
I know that there are no absolutes. My resistance to going with a roller are two-fold. First is expense. Why spend the money IF all the risk factors of a FT setup are addressed and failures are no more likely than they would have been 40 years ago?
Secondly, part of the appeal of the FT setup is reduced noise. Are all roller setups noisy though? Is a solid roller just as noisy or is it the weight and complexity of the hydraulic roller that makes them clatter?

 

[1967coronet]

Not sure if I just got lucky .
My comp cam and lifters flat tappet, hydraulic is the XE 262H. 474 lift / 224 duration at 50.
Pretty mild compared to what most of you guys are running.
Comps instructions said to limit open spring pressure to 260lb.
I had purchased a set of crane springs # 99839 that pretty well mimic the mopar oem hp spring and damper. But at a crane advertised 280 lbs I used my old worn oem springs for the break in.

Used comps assembly lube, and Gibbs break in oil.
Timing was pre set and a known good carb primed.
I did a near 30min break in at a up and down rpm scale max aprox 2,500/ 2,800 rpm.
Few months later and a couple thousand miles I was swapping intakes so I got a good look .

 

[Kern Dog]

It may be obvious to some but why do milder cams survive while the bigger cams seem more likely to fail?
Is it because the bigger cams have a greater stress between the cam lobes and lifter faces? Is it that the springs place more pressure on the lobes and lifters that make the oiling even more critical?
I remember the factory recall that Chevrolet had in the 70s or 80s about the failed camshafts in their 350 small block engines. That was supposed to be due to the grade of metal used in the parts.
I’ve seen videos where modern cams and lifters have been tested for hardness and compared to readings taken from original vintage parts. The numbers are either identical or similar so maybe the problems actually do lie elsewhere. Has anyone actually measured lobe taper before installing a cam? How about the crown of the lifters?
That “love him or hate him” uncle Tony had a video where he bought some lifters from an auto parts store and tested them for crown. The ones he didn’t like were returned for a refund. Some time later he went back to the store and bought lifters again and was given the same exact lifters he bought the first time… the store didn’t send them back to the manufacturer as defects, they just put them back on the shelf to sell to some unsuspecting customers!

 

[toolmanmike]

Bad new lifters and bad lifter bores are the major causes. The lifters have got to spin freely and the lifters must have a crown on the cam end. The cams must have a certain amount of lobe taper as well.