The Truth about Flat Tappet cam failure

[tRustyK5]

While I still use Hi zinc oil, once the cam is properly broken in, and survives, the high zinc oil isn't as necessary.
Idk but what other engine makes are having high FT cam failures.
I am sure the bean counters didn't just skimp on Chevy flat tappets

It's not a brand specific problem, Mopars, Fords and every other brand out there are dealing with the same failures.

Back in the day you could severely fock up the break in and still be fine. Today you can have a perfect break in and still be focked.

Roller cams for peace of mind, and better power.

 

[tRustyK5]

New confirmation of theory...video is worth the watch!

 

[76zimmer]

Good to know!
I should double check my 30 yr old cam and lifters.

 

[Bent77]

Yeah. Probably not. They made it that far, they’re good

 

[76zimmer]

Seems like everytime I run the valves, the clearance is always the same +/- .002

 

[1-ton]

New confirmation of theory...video is worth the watch!

Tony Mentions DD Speed Shop YouTube channel. That cam failure may have been from a bent connecting rod making contact with the cam. In the video that DD Speed Sop discusses the cam failure when he shows the cam that failed the cam lobe is not only flat, but there is a chunk taken out of it. In the second video after the flat cam problem he announces that he found a bent connecting rod that the engine may have had the whole time. The cam lobe that went flat look like it was from the #8 cylinder, and the bent rod look like it was from the #7 cylinder, which could be close enough to make contact when bent.

 

[tRustyK5]

All good points, but the lifter that was the smoking gun for Uncle Tony was not #8, but one somewhere in the middle that had a wide wear stripe on it showing definitively that it was not rotating and was about to fail. That witness mark led Tony to his theory about poor machining being the true root of the cam failures.

Dan's big block was junkyard el cheapo stuff, which he knew and never pretended it to be anything but that. Even if the bent con rod was pre-exiting, and even if it did take a chunk out of the #8 lobe edge...it didn't eat that lifter, or the other four that failed. Dead flat lifters and not enough lobe taper on that cam did all that.

 

[1-ton]

All good points, but the lifter that was the smoking gun for Uncle Tony was not #8, but one somewhere in the middle that had a wide wear stripe on it showing definitively that it was not rotating and was about to fail. That witness mark led Tony to his theory about poor machining being the true root of the cam failures.

Dan's big block was junkyard el cheapo stuff, which he knew and never pretended it to be anything but that. Even if the bent con rod was pre-exiting, and even if it did take a chunk out of the #8 lobe edge...it didn't eat that lifter, or the other four that failed. Dead flat lifters and not enough lobe taper on that cam did all that.

None of what I posted was about Tony's cam failure problems...just the DD Speed Shop YouTube channel problems.

If a chunk of metal is taken out of a cam lobe, it will definitely kill that lobes lifter in no time flat. Dan from DD Speed Shop never mentioned any other lobe failure just that one was making the noise he diagnosed.

 

[tRustyK5]

Dude, the cam failure Tony talked about, and showed was Dan's bbc cam failure. The striped lifter was from Dan's big block. Dan's big block ate four or more lifters to varying degrees. The worst was the destroyed and chewed up # 8, but there were others nowhere near the bent con rod that also failed...and I know I'm repeating myself here...including the one lifter with the witness stripe on it from the middle of the engine. Again, all from Dan's engine. Dan and Uncle Tony are friends

To further expand on this Dan did a follow up showing the remaining lifters from that Comp set were all dead flat, no crown to them at all.

Dan did mention the other lifters, and showed them all btw...

Lifter autopsy showing multiple failures and where they were starting at 4:25

 

[1-ton]

Dude, the cam failure Tony talked about, and showed was Dan's bbc cam failure. The striped lifter was from Dan's big block. Dan's big block ate four or more lifters to varying degrees. The worst was the destroyed and chewed up # 8, but there were others nowhere near the bent con rod that also failed...and I know I'm repeating myself here...including the one lifter with the witness stripe on it from the middle of the engine. Again, all from Dan's engine. Dan and Uncle Tony are friends

To further expand on this Dan did a follow up showing the remaining lifters from that Comp set were all dead flat, no crown to them at all.

Dan did mention the other lifters, and showed them all btw...

Lifter autopsy showing multiple failures and where they were starting at 4:25

The entire cam was not bad. That happened only after the one catastrophic cam lobe and lifter failed. Then the rest of them went. Once one cam lobe and lifter has a catastrophic failure the entire lube circuit has is compromised , and then entire cam goes bad after that.

 

[Bent77]

I’ve never lost every single lobe on a cam

 

[fastazz81]

You should try harder.

 

[1-ton]

I’ve never lost every single lobe on a cam

An engine can loose 1, 2 or 3 at most cam lobes, after that most engines will stop running before it gets that bad.

 

[Bent77]

So what are we looking at? Bad heat treating? Non parkerized? Poor machining? Chinesium junk?

seems odd that 20+ years ago manufacturers made cam/lifter sets without issue. I know what I think.

Poor machining for most all of these


All the ones I’ve flattened lost 4-6 lobes, all in the front where the oil gets to last on a SBC. All factory 70s cams
The last flat tappet cam I installed was 2009, Edelbrock. No issues

 

[tRustyK5]

So what are we looking at? Bad heat treating? Non parkerized? Poor machining? Chinesium junk?

seems odd that 20+ years ago manufacturers made cam/lifter sets without issue. I know what I think.

Bad machining.

 

[K5Devil]

I'm reviving this thread because I am hunting down parts for my 383 build however I have been weary of Cam/lifter failure.

My dad built a 301 stroker for a customer of his 57' chevy. The main rotating assembly was done at a high quality and trusted machine shop here which unfortunately the old grey beard retired from a few months back.

My dad installed the heads/cam/ and lifters etc, (Comp cam and lifters from summit)

Well, after the first run within 5 minutes the cam was eating the lifters.

The engine was only ran for about 5 minutes.

the engine was taken apart, bearings inspected and reassembled.

he then went with a roller set up and haven't had any issues since.

To me it looked like the lifters were soft as the cam cut right through them like butter.

 

[1-ton]

I'm reviving this thread because I am hunting down parts for my 383 build however I have been weary of Cam/lifter failure.

My dad built a 301 stroker for a customer of his 57' chevy. The main rotating assembly was done at a high quality and trusted machine shop here which unfortunately the old grey beard retired from a few months back.

My dad installed the heads/cam/ and lifters etc, (Comp cam and lifters from summit)

Well, after the first run within 5 minutes the cam was eating the lifters.

The engine was only ran for about 5 minutes.

the engine was taken apart, bearings inspected and reassembled.

he then went with a roller set up and haven't had any issues since.

To me it looked like the lifters were soft as the cam cut right through them like butter.

Hard to say if the break in procedure was done right if not there to see it first hand. I had a person ask me to help with the break in of a new engine, and when I got there he had a friend there that was supposed to be his engine guru in charge of the whole deal. When they tried to start the engine it just popped and banged, yet they kept cranking the engine over and over again anyway. I tried to warn them that the engine needed to start up right away, and be run up to 2000-RPM instantly, but the engine guru friend got offended, and told me to shut up. I just sat there, and did not say a word for about another 1/2 hour watching the carnage happen, then I made an excuse to leave. I later found out that they lunched the engine, and it had to come out and be rebuilt again. The guy asked if I would help, but I just made excuses that I was busy.

 

[K5Devil]

Hard to say if the break in procedure was done right if not there to see it first hand. I had a person ask me to help with the break in of a new engine, and when I got there he had a friend there that was supposed to be his engine guru in charge of the whole deal. When they tried to start the engine it just popped and banged, yet they kept cranking the engine over and over again anyway. I tried to warn them that the engine needed to start up right away, and be run up to 2000-RPM instantly, but the engine guru friend got offended, and told me to shut up. I just sat there, and did not say a word for about another 1/2 hour watching the carnage happen, then I made an excuse to leave. I later found out that they lunched the engine, and it had to come out and be rebuilt again. The guy asked if I would help, but I just made excuses that I was busy.

It failed nearly instantaneously. Wasn't even enough time for break in.

We have a lot of engine builders in this town and we spoke with many of them after this incident and they all said there is a major lifter epidemic in the country they too are having engine failures after being rebuilt in the same fashion. most said the issue is the lifters not being heat treated properly.

I was wondering if anyone here had any luck on a new engine build recently

 

[1-ton]

It failed nearly instantaneously. Wasn't even enough time for break in.

We have a lot of engine builders in this town and we spoke with many of them after this incident and they all said there is a major lifter epidemic in the country they too are having engine failures after being rebuilt in the same fashion. most said the issue is the lifters not being heat treated properly.

I was wondering if anyone here had any luck on a new engine build recently

I installed a new GM Goodwrench small block TBI Chevy crate engine about 15,000-miles ago. I removed the stock cam, and put in a mild Comp Computer Controlled cam with AC/Delco lifters. I went with the Delco lifters due to concerns with aftermarket lifters. The whole thing went smoothly, and 15,000-miles later the engine still runs like a champ.

 

[K5Devil]

I installed a new GM Goodwrench small block TBI Chevy engine about 15,000-miles ago. I removed the stock cam, and put in a mild Comp Computer Controlled cam with AC/Delco lifters. I went with the Delco lifters due to concerns with aftermarket lifters. The whole thing went smoothly, and 15,000-miles later the engine still runs like a champ.

I am considering going Roller$ just to keep from getting hosed on this lifter debacle. Nice. I think If I do go flat tappet I will try to get the delphi lifters.