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Old 01-22-2023, 03:54 PM
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What has to be kept in perspective so the whole bad roller lifter theory doesn't run off the rails ( wait....too late) who'd a thought

Is that it wasn't the roller lifters fault that 64speed lost an engine, and he's aware. That whole mess could have been avoided with several other key factors. He very likely still could have had a failure with flat tappet given the reasons why that scenario started in the first place.

A flat out lifter failure without an actual root cause is actually pretty rare when you look at the percentage of issues, like with most anything.
So I don't buy into the whole "roller lifters are horrible" gloom and doom sillyness.
Basically like most everything else, gargage in, garbage out. The end result is what you make of it.

I'm sure 64speed is going to be fine with his current choice.

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Old 01-22-2023, 04:13 PM
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Originally Posted by geeteeohguy View Post
I like roller cams in late model engines that were born with them. They seem to last.
That's a great point that should be expanded upon. There is a huge difference between OEM and what hobbyists are trying to do.

Anyone that has actually played with the OEM roller stuff knows some of the reasons why they have a good track record.

On the LS and Ford stuff I've messed with for instance, after they've been run a while It's rare that I've seen spring seat pressure over 80 lbs. So what did they start with? 100lbs.?? 110?? The last LS I did there wasn't a single spring that tested 100lbs. on the seat. That's not even enough spring for a decent flat tappet in a Pontiac engine, especially those that run wide seat angles.

You can also look at the OEM lobe profiles on these camshafts, which are very slow and lazy, they don't need a bunch of spring anyway.

Add to that the valvetrains are light, again they don't need much spring. Low stress, low rpm in some cases, longevity has a better success rate.

Now look at what hobbyists are doing. How many actually rebuild their hotrod engine and put the stock cam profile back in? Even with flat tappets that rarely ever happens. Even if you did, the blueprint style OEM camshafts have still been tinkered with by the manufactures in some shape or form.
Most anything out there requires a different spring package. Some get more extreme than others. Some engines, like these Pontiacs, require more spring than a typical SBC or LS thanks to the heavy valvetrain to start with, that's before you even factor in a more aggressive lobe profile, or flat seats.
How many times have we heard these stories and not really know the full back round? How many actually go through the trouble to setup correct valvetrain geometry, valve spring pressures, or, better yet, even want to spend the money for the better parts. That's a big one!! Most go for what's cheapest and it's been that way on everything since about the beginning of time.

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Old 01-22-2023, 04:23 PM
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Originally Posted by Formulajones View Post
What has to be kept in perspective so the whole bad roller lifter theory doesn't run off the rails ( wait....too late) who'd a thought

Is that it wasn't the roller lifters fault that 64speed lost an engine, and he's aware.

I'm sure 64speed is going to be fine with his current choice.

I don't agree with the first part of this assessment. The weakest link (the link bar pivot) failed when over-revved, allowing the lifter to turn sideways, dig into the cam and shear off the thin casting around the lifter bore.

Had it been an HFT, the worst that would have happened is a collapsed lifter and/or bent pushrod.

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Old 01-22-2023, 05:09 PM
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Originally Posted by NeighborsComplaint View Post
I don't agree with the first part of this assessment. The weakest link (the link bar pivot) failed when over-revved, allowing the lifter to turn sideways, dig into the cam and shear off the thin casting around the lifter bore.

Had it been an HFT, the worst that would have happened is a collapsed lifter and/or bent pushrod.
I don't think the whole story was actually posted so I'll lay some of it out.

To start with, yes a flat tappet cam could do the same or even worse damage in an over rev situation when you have loss of valvetrain control. Ever seen an over rev situation kiss a valve, bends the valve, which then breaks the valve head off when it contacts the seat, then takes out the block and the head?? I have. Doesn't matter what camshaft was installed in it.

Now in 64speeds case, it wasn't a lifter failure. There was a root cause.
It goes way back when the build started, he had the camshaft spec'd by Paul C. Now Paul has been using that camshaft for a very long time and knows exactly the spring package it needs with his valve job and valvetrain. He's run that setup on the dyno more times than anyone here can count. Numerous people on this forum are running that exact package, including an engine I've built.
Here's where things take a turn. 64speed only bought the cam, and at the time didn't have the money for Paul to build the rest of the engine or even spec other parts.
Fast forward to 64Speed buying cylinder heads from Butler. Comes with Butlers spring package. That's a red flag to start with. What Butler thinks should work with that cam you could be pretty sure it's not what Paul would like to see. Was Butler consulted about this? Hard to say, when I brought that question up it wasn't answered.
Fast forward to engine assembly, 64Speed had decided to have yet another shop build the engine with supplied parts. Cam from Paul, heads and valvetrain package from Butler, and no telling if the engine builder checked to see if the spring package was satisfactory. Did anyone contact Paul on this? Again that question went unanswered. Now this engine has entered a 3rd party at this point.

So it's a pretty good bet the engine went together with springs that weren't up to the job.
Couple that with the fact that 64speed has no rev limiter, goes out and misses a gear, over revs the engine. Guess what...........loss of valve train control crashing the lifters and taking out the block. That's the gist of it, I'm sure 64speed could fill you in on more details, but this for sure was not a simple roller lifter failure all on it's own. It was just an unfortunate set of circumstances that created a domino affect and led to a vary expensive conclusion.

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Old 01-22-2023, 10:21 PM
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Originally Posted by Half-Inch Stud View Post
Polishing the lifter Bores of 50 year old Blocks ought to be a thing, a standard process.
It’s way too easy to remove too much material for the lifter bores. A “slick up” with an appropriate size and grit ball hone should do the trick. It beats the expense of having to bush sixteen lifter bores.

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Old 01-23-2023, 09:08 AM
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I started a thread on this - applies here:

"Flat Tappet Cam Failures?, we investigate why and check the hardness of several cams and lifters!" The short of it is the way the lifter is ground and the way the cam lobe is ground seems to be main culprit rather than hardness.

https://youtu.be/DMFikj-TAqo

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Old 01-23-2023, 09:10 AM
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No the whole story was posted. I revved it to 7200, it destroyed the lifter then destroyed the block. With that roller it literally revved so fast that before I could lift it was over.

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Old 01-23-2023, 10:28 AM
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The over revving is only part of the equation. Lifters don't just fall apart from RPM. You obviously lost valve train control. The series of events is above, with the unanswered questions included.

It was even asked if those springs were tested after the fact, now that it was apart and in pieces, that again as I recall went unanswered.

None of these type of threads does anyone any good without good investigation work. Otherwise it's just a bunch of conjecture and wrong conclusions drawn, usually blaming something that wasn't at fault to begin with.

Good ole internet rumors get started.

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Old 01-23-2023, 10:49 AM
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" I revved it to 7200, it destroyed the lifter then destroyed the block. With that roller it literally revved so fast that before I could lift it was over."

Inadequate valve spring pressure.

I agree with Larry.


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Old 01-23-2023, 10:52 AM
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Apologies for a little side story about roller lifters.

Early on in the Boss Bird project, we destroyed a roller lifter wheel. After discussions with nitro experts, we determined that the problem was too much valve lash. Recall that we had to use the straight-70 weight goop. Turns out that it has a pretty stiff film (good thing for nitro) and if you don't put a lot of downward pressure on the rocker arm to squeeze it out, you'll get a false (too loose) lash setting. After changing our lashing procedure, there were zero roller wheel failures. So the lesson from that is that roller lifter wheels don't like to be bashed into. Loose lash or valve float would cause that.

Back to topic.

Eric

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Old 01-23-2023, 11:06 AM
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Dave (64speed) also had BB Chevy rockers in that engine. Not saying this contributed to the issue but feel it’s important to note.

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Old 01-23-2023, 11:32 AM
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Autopsy synopsis by my builder was when the pushrods broke (not bent) the lifter jumped the bore totally. It was laying in the valley tray in big pieces.

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Old 01-23-2023, 11:38 AM
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So now you're saying it's a pushrod problem? They just broke on their own?

This really gets back to the old question, were the springs tested? Were they to the spec that Paul recommends on that camshaft? Were they tested during engine assembly or after it's demise?

What did you find when tested for seat and open pressures?

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Old 01-23-2023, 11:55 AM
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No I’m not saying it’s a pushrod problem. I’m saying the cam was top notch, the lifters were not. I agree the valvetrain lost control but if I’d had a more durable lifter than the cheap Lunatis in it I might have been ok, if I had been able to shut it off in time it probably would have been ok. Everyone is looking for one thing when it’s the dismal tide. I revved it way past it’s redline and a symphony of things took a ****

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Old 01-23-2023, 12:08 PM
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So as those questions linger again....

Valve train control is a real thing. I feel your pain, but this whole deal is made out to blame lifters by some, and honestly it's a scenario that is more involved than that.

Read post 44 again. It goes back long before the thread of over revving the engine.

If this whole flat tappet deal works out good for you that's great, hope it gives long lasting enjoyment. Best of luck on break in and many miles

It's just unfortunate that some people have to turn it into a "hydraulic roller is a bad idea" scenario and then post a bunch of misinformation not knowing all the facts. That's why I put post 44 up to lay the ground work and give a better idea where all this started, in hopes of clearing up the conjecture.

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Old 01-23-2023, 03:06 PM
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No I’m not saying it’s a pushrod problem. I’m saying the cam was top notch, the lifters were not. I agree the valvetrain lost control but if I’d had a more durable lifter than the cheap Lunatis in it I might have been ok, if I had been able to shut it off in time it probably would have been ok. Everyone is looking for one thing when it’s the dismal tide. I revved it way past it’s redline and a symphony of things took a ****
That is possible. When things go terribly wrong, there can be contributions from many parts in the system that when added together equal disaster. Marginal lifters, lifter clearance, BB Chevy rockers that may not have had ideal geometry, pushrods not up to the task, valve springs not ideal for the cam, lots of things to go wrong. On the flip side, with the best parts money can buy, matched correctly, and working in harmony, a Pontiac engine can survive extreme RPM abuse. We had a transmission failure on the 1-2 shift that allowed the Ram Air V Boss Bird engine to run up to 11,200 RPM. The tell tale electronic tach verified this as well as the computer data. Valve train and all engine components were intact, no failures.

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Old 01-23-2023, 03:11 PM
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Yeah it's not unusual these days to spin hydraulic roller lifters to 8500 or more with things setup properly on a street/strip engine. Bunch of guys doing just that, with boost even.

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Old 01-23-2023, 04:11 PM
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We had a transmission failure on the 1-2 shift that allowed the Ram Air V Boss Bird engine to run up to 11,200 RPM. The tell tale electronic tach verified this as well as the computer data. Valve train and all engine components were intact, no failures.
WOW!

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Old 01-23-2023, 05:54 PM
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I was running the springs/cam Paul Carter ordered and prepped for me along with oil pump mods. They were shipped to me from him. As far as the concern over valvetrain geometry with BBC rockers what I can tell you is I bought Voodoo rocker 1.65 and they were not even in the ballpark. I honestly think they were misboxed cause there was no way they would work. Wayne told me that he had great luck with BBC rockers in the past so we tried it and the contact pattern was beautiful. I have some pictures of valve tip contact IF I can find them but that’s a long time ago. As far as failures I admit I am an amateur but when the whole damn lifter is out of the bore laying on its side with broken pushrod pieces in the pan it’s not rocket science or at least I don’t think it is. My engine ran like a sewing machine…until the failure. I had very little valvetrain noise beyond the “noisy lifter” lunati noise that MysticMissle speaks of.

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Old 01-23-2023, 09:35 PM
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Missing a gear or having something in the drive terrain break, then free revving full throttle well past the engines intended power band is a lot different than making high RPM dyno pulls. A lot more acceleration on the valve terrain. It breaks stuff.

The same scenario, with a flat tappet lifter getting thrown out and having it get wedged in the rotating assembly is bad too. Really bad.

Get a rev limiter.

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