Hello everyone.
I just rebuilt a 305 for my 83 Firebird. I put in a Howards Cams Rattler cam, lubed everything with the included special sauce, primed the engine and did the magical rain dance Howards specifies; vary around 2500-3000 rpm for 10 minutes, let cool down, do it for another 10 minutes, don't let it idle.
I used a high zinc mineral oil and I did have to shut it down twice, to refill coolant and to adjust the carb.
After the break-in oil change I started hearing a tapping noise, and found the #1 intake lifter loose. Resetting all the tappet clearances I found it's short on lift- less than half at the valve, 0.232" when specified gross is 0.480". Checking another random valve netted 0.456", at which point I made myself a drink.
I fear wiped cam lobes from a bad break-in, the oil has more metallic flake than firemist paint. I have driven it maybe 5 miles in total, though not since finding the loose lifter. I don't think a collapsed lifter would cause this, though I don't know, I work with solid lifters and diesels mainly.
Anyone experienced something like this?

 

Sounds like a wiped cam lobe despite your effort to prevent it. With that much glitter in the oil, it's pretty mandatory to pull the intake and inspect the lifters and cam lobes.

 

Not great news. Will update tomorrow.
Thank you.

 

Been there - done that.
What was your valve spring setup? Did you measure all the valvetrain clearances - retainer to seal, coil bind, piston to valve?

DON'T run this engine any more. That "glitter" is hardened cast iron shrapnel and your oiling system has distributed it throughout the entire engine -
the oil pump, ALL the bearings, the cylinder walls and piston skirts, inside the lifters - EVERYWHERE! You have to clean it out completely before
you start over. And NO, the oil filter didn't trap it all for you.

 

Stock rockers and pushrods, with Howards single valve springs and accompanying retainers with custom shims to bring everything to 1.7" installed height. I have 416 heads with those deep spring seats on the exhaust valves. Everything measured out, everything clears.
I will not drive it; though I want to. Pulling the pan in the car sounds like fun.

 

Yep, the cam is wiped (sadly). And no, it's not because of improper break-in. It's most likely improperly machined lifters, or not spinning in their bores. Of course the cam manufacturer will try to blame it on you. That's what they do...

 

#1 intake and exhaust. No wonder it was short on lift.

I'll wash the engine thoroughly with diesel and put the old cam back in.
Does anyone have experience with Crower roller cams?Specifically their EFI-grinds? After this catastrophe I will not roll the dice unless I have to.

 

What information are you looking for? What about the efi grinds do you want to know? In general, they're like any other roller cam. Are you thinking of retrofit or something else?

 

VERY VERY VERY BAD idea. Especially if you aren't absolutely positively CERTAIN which lifters came out of which hole.

Crower has been making cams for over 60 yrs that I know of. A very reliable, "old-skool" type of company. Never the "cheapest" for anything, butt very often "the best" of whatever they make. Whether they offer a cam that will fit your needs, about which I know nothing besides that it's a 305 in a 83 Firebird, I can't be sure, butt I suspect they do.

If you're working on the original 83 305, you'll need a "retrofit" style roller, with link-bar lifters, and a cam button. If this is still a largely stock LG4 (base model carbed 305) or the CrossFire motor, look at their part #s 00400 and 00481. Their matching lifters for those are 66313. You WILL need good valve springs; in 2026, I'd suggest LS6 ones such as from TSP, with the Comp 787 "adapter" retainers and matching keepers, shimmed to the correct height.

 

Did you reuse your old lifters with that Howards cam, or new everything?

 

Good point: those look like they're MUCH more experienced than only a break-in run.

 

New everything sans the pushrods and rockers. Complete kit from Howards.

I did the break-in, changed oil and filter, and drove about 5 miles up and down the road before it started ticking (a lot) and I parked it. The lifter in the picture is the worst of them all, the cam lobe is almost gone. The lifter spun freely in the bore, I am not sure why it went so poorly as it did. My two theories are 1) rotten luck with the cam and lifter set and 2) (suggested by others) too much spring pressure and load on the cam.

Yes, I am looking at link-bar rollers. It's a "stock" LG4 with some newer replacement parts, better valve springs and retainers.
Got a new set of lifters from Comp and a mild cam from a 350 to go in it for now, most things should be better than the stock LG4 cam afaik. Not willing to put more expensive parts in until I know how well the rest of the motor has coped with this.
For now I'll run the Howards springs, I will look at the springs you recommended, thank you.
I was looking to convert to EFI in the future, I see Crower has specific grinds with wider LSA for more consistent manifold signal for a speed-density type EFI. Not cheap, but I've bought once and now cried twice. Looking at some medium grinds that will blend manual driveability and power.

 

Make sure you run a high zinc oil the whole time, not just for break-in. The flat tappet cam really needs it at all times. Might be some that disagree with me and that's fine, stick with high zinc and drive worry free about lubrication.

 

Not to start a debate here (I run a ZDDP additive at all times), but too much "zinc" is just as bad as not enough. Additionally; just like people that use flouride toothpaste still get cavities, people who use ZDDP still experience cam failures. I broke-in my newly-built smallblock Ford in 2008. I didn't know about the ZDDP thing, and just used regular motor oil (Valvoline 10w-30). I never had any problems with it.
The whole "zinc" thing was more of a scapegoat for cam manufacturers to avoid having to warranty their products. I've been lucky; I have done 4 cam break-ins (2 Ford & 2 Chevy) and so far have a 100% success rate...

 

I ran a "high" zinc (1200 ppm) 10w-30 mineral oil, some say to use a plain 30-weight and additive ZDDP for breaking in cams, Crowers among them. Afterwards I changed it for more of the same 1200 ppm, so that shouldn't be it.


I've both suspected and read as much, that it was and is an easy way to avoid warranties and excuse their "dodgy cores" and cheap raw materials. Some of their arguments are true, oil has changed since flat tappet cams were the norm, but cams went flat back then too.


I went to the machine shop in my lunch break and we gave it all a measure just for kicks. Half the lobes and lifters are "fine", the lobes show wear marks in the finish but no measurable wear. Half the lifters are still convex, nothing measurable. Three lifters and lobes are in varying states of death, with the two worst lifters showing heat discoloration; I would estimate they reached around 200 degrees celsius, between 350 and 400 degrees fahrenheit judging by their straw colour.
The rest have lost their convex tip to varying degrees and started to flatten out. There's no real pattern to discern, they aren't all intakes, exhausts, drivers or passengers side, towards front or towards the back.

Sometimes these just go wrong I suppose. David Freiburger says it's a 50/50 shot of the cam living and to "just buy a roller cam". Some are lucky and never have one fail, I've now had one of each.
Excited to see how my "new" cam will tip the ratio.

 

You said that your springs were set at 1.700".
Even if you chose the smallest Rattler camshaft, I suspect that you didn't have enough bottom of retainer to valve seal clearance.
You probably were also very close to coil bind. To use a cam with that much valve lift, your spring set heights should have been in the 1.750 to 1.800" range.

Here is a tip: (ready to fire engine) - next time paint lines on your pushrods (silver paint marker) and rotate the engine more than a few revolutions (not with the starter).
The pushrods should rotate a little bit for each revolution. That means that the lifter is rotating also. If even one doesn't rotate, that lifter/lobe combination will most certainly
become a lathe and you will be right back in the same situation that you are in right now. A flat tappet lifter must rotate and no amount of ZDDP will prevent the destruction.

 

I misspoke: I had 1.8" installed height on all my springs. I re-read my original post where I also called the rockers lifters by mistake.

It is still possible that it was too much lift/spring pressure for that head and cam. The retainer-seal clearance varies depending on who you ask with some saying they kiss at above .450 lift and others run .500 no problems, which leads me to believe the castings are inconsistent in that area. I don't recall my exact measurement but I did measure it on the bench and it came out over .520 on all of them, I had the mildest Rattler at .480/.488. It is possible this was still too tight, especially with RPM. It rotated over fine by hand, at least with the plugs out, and aside from the ticking of that lifter dying it never made any undue noise.

Next time I will mark my pushrods- the lifters all rotated fine by hand both putting them in and and taking them out, even the ones that had mushroomed and there were fresh wear marks of something having rotated up and down the bores on all of them, but I never visually checked if they actually did. I don't think this was the issue as put them on a surface table and they were all evenly destroyed all the way around, it didn't dig in on one side like I would believe they would have if they got stuck in the bore, the cupping was even all the way around on the bad ones. But I will still check to make sure, thank you.

I have refined my theory of "too much pressure on the valve train/cam" to me overtightening the rockers. I went to 0 lash and then one full turn as my Haynes manual is from the late 90s and said to do that, I later learned they went to half-turn due to cam wiping problems and for breaking in some advise to run 0 lash and set proper clearances afterwards.

 

Lifter preload (# of turns past zero lash) isn't a cause of wiped cam lobes, unless SO EXTREME that valves hang permanently open; and even then, the engine would run SO BAD, that it would be impossible to notice.

The whole point of a hydraulic lifter is to self-adjust, within a reasonable range, to randomness in rocker arm lash adjustment. As long as the preload leaves the plunger inside the lifter within that range (about a turn and a half to 2 turns wide), the lifter takes up all the lash, the valve motion remains essentially the same, and the cam/lifter interface sees the exact same loading.

"They" didn't "went to half-turn due to cam wiping problems". The factory always used 1 full turn past zero lash (or at least, whether that was the ACTUAL PROCEUDRE they used in the factory, that was their procedure's approximate effect). They did this because the more preload is used, the longer the engine's "regular maintenance" interval can be in that area. Think of this as the "100,000 mile" setting. Industry standard for repairs (Chilton's for example) has mostly been ¾ turn (75,000 miles). "Performance" aftermarket recommendations are more like ½ turn, because people in that bracket will generally be maintaining their valve train more regularly anyway, so high mileage isn't as much of a concern. Settings for pure racing type use, where maintenance will generally occur at less than 10,000 mile intervals, have used ¼ turn or even less. NONE OF THIS has anything whatsoever to do with destroying cam lobes in any manner way shape form or fashion.

Traditional advice for builds w double springs, with or without damper (a damper is NOT a "spring"; a single w damper has 2 pieces, and double w damper looks like a "triple" spring to the eye), has been to remove the inner spring for break-in, and put it back after that's complete. You don't have that though so it doesn't apply to you.

A "flat tappet" cam lobe isn't flat, and a "flat tappet" (tappet is an old word for "lifter") isn't flat either. The lobe is a few thousandths taller on the side toward the rear of the engine, and the lifter surface is spherical with a radius of about 60". The design intends to create theoretically only a single point of contact between the lobe and the lifter, and for that point to be near the outside circumference of the lifter face, thereby imparting a force to the lifter tending to rotate it. This makes the interface look kinda like a ball or roller bearing. There is NEVER supposed to be ANY "rubbing" kind of action on these surfaces. Of course the metal isn't perfectly hard, and so deforms slightly, such that the interface is more of a line on a radius of the lifter than a point; butt a properly working one produces a sort of "ring" around the lifter surface around 2/3 of the way from the center to the edge and maybe 1/8" wide, and wear on the lobe only on the rearward half of its surface at most.

As far as break-in oil, synthetic is considered a bad choice, because it's TOO good. The lobe and lifter have to "stick" together a little bit for the whole system to work; in a way, friction is actually our friend right there. The reason for straight 30 weight oil is that "viscosity modifiers" added to the oil to make it multi-grade, aren't lubricants; so, any multi-grade oil, and the wider the range of the grades the greater the effect, has less actual "oil" in it than single-grade oil. The whole zinc thing is due to catalytic converters: zinc, and several other elements that promote lubrication including phosphorus, will "poison" the catalyst, and therefore have gradually been eliminated from most oils, as emissions regulations have tightened. AFAIK there's an "optimum" level of zinc in the oil for pre-emissions engine features such as flat-tappet lifters and pre-emissions oils, which is, around 1200 ppm. Any more than about 1500 ppm is a waste, and any less is inadequate, for those older oil and engine parts types. Nowadays, with roller lifters being virtually universal, it isn't needed at all, and oil is just overall better anyway nowadays, so most consumer oils have virtually none at all.

I don't think anything you did about how you built the engine had anything to do with this. I doubt the oil you used did either. This whole deal has become almost like religion. Uttering the correct incantations with the proper reverence, bowing 3 times before and after the muttering, washing your body starting with one particular part and proceeding through all the others in a specific order. All that sort of thing, is merely human attempts to appease a mysterious unseen unknowable unpredictable (key concept: unpredictable) and nonexistent "power", that can produce rain, cause disease, promote long life, provide "happiness" and "peace", and have all sorts of other effects on the human condition, and must be propitiated and appealed to and kept happy at all times, and all those "worship" activities are the result. Cam lobe wipeout lore works about the same way. Wipeout is inherently unpredictable, and unfortunately, quite likely; so like disease for example, there are some things we can do to ward it off (stay clean, avoid eating spoiled food, get vaccinated, and so on), butt there's STILL an unpredictable probability that we'll get sick and die. You can separate the "lore" regarding cam wipeout the same way: things that promote the action of the lobe/tappet interface as described above, have an effect; all the rest of that, is like worshipping the god of rain while the priest with the feathered headdress distributes the correct number of sprinklings of freshly-drawn water from the sacred well toward the 4 points of the compass in the correct order and the chorus of virgins invokes the wisdom of the ancient chants, to generate rain to get your crops to grow. UTTERLY USELESS AND OF NO EFFECT except for emotional comfort, aka "I did all I can do, now it's up to providence".

We all used to use moly grease as break-in lube, SPARINGLY, since the "gritty" nature of the moly particles always seemed to help, while also coating those surfaces semi-permanently with the extremely hard material. Moly grease comes with a serious drawback however, namely, it plugs up oil filters FAST, like using your vacuum cleaner on drywall dust; as a result, "wisdom" these days therefore is, it's bad, since people who used too much used to kill their motors due to oil starvation. All of the "change your oil filter after the first 5 minutes of running" and that sort of stuff, which has become like ancient religious wisdom and lore these days, had its origins in the dim long-forgotten past of our ancestors, and has become "we've always done it that way" today for no reason anyone can remember, although there WAS good reason for it at one time. You might consider using moly grease SPARINGLY on your lifters therefore, and change your oil filter soon after first startup; say, after 100 miles. Another thing that's critical is not letting engine RPM drop too slow during break-in, which means, the engine must be COMPLETELY COMPLETE and ready to run, in particular the cooling system, before the first time you hit the key. My own personal discipline is, I assemble everything COMPLETELY COMPLETE, to the point that the car is as ready to drive as I can get it. By COMPLETE I mean, all accessories installed, all belts & hoses on and tight, preload adjusted as I deem proper for the engine's use (see above), valve covers on and glued down, all wiring in its looms and clamps and whatnot, cooling system and all other fluids full, down off the jack stands with the wheels on. I pour an ounce or so of fuel into the intake and install the air cleaner, set the idle deliberately too high, and literally CLOSE THE HOOD and reach through the window for first startup. Pay particular attention to the word "discipline": I'm meticulously careful about building the engine and timing the distributor and all that stuff so that I can be absolutely CERTAIN that the engine will start IMMEDIATELY, the FIRST TIME I hit the key, and will be READY TO DRIVE soon after; there's no "let's see if it runs", "I just want to hear it run", "make sure I got it right" (because I DID and I'm already sure of it), or ANY of that. Once it starts I watch for leaks with the hood closed, then after a minute or 2 I open the hood, check the transmission fluid and coolant and PS fluid and all such as that, all while the engine runs at fast idle, maybe 1800 - 2000 RPM or so, until FULLY warmed up (200°F or whatever, on the coolant temp gauge), WITHOUT letting the RPM drop below 1500. Then shut the engine off, clean up around the car, start it back up, and IMMEDIATELY drive it. Usually that's enough to promote development of the right behavior of the lifters (constant rotation), such that they'll act right afterwards. And although I haven't built a flat-tappet engine for over 30 years now, I STILL used moly grease SPARINGLY as my lifter assembly lube right up to the last one I built.

 

The engine is ready again. I flushed it with diesel and ATF, running the oil pump with a drill and screw driver, wiping down everything, flushing it again with some barely used 5w-30 and another flush with diesel, until what came out was metallic-free. Just for fun I strained it all through coffee filters (plural, they clogged very fast).

I put in a swap meet 350 cam with a liberal coating of moly grease and new Comp Cams DLC lifters that have soaked for a few days. I filled it with plain 30w mineral oil that alleges it is specifically for older/"antique" vehicles (API SG/CD) and Comp Cams own break-in additive. All is set for the beginning of the 30 minute rain dance that Comp specifies, perhaps it will bring better harvests than Howards'.

After setting the valve lash (0 play + 1/4 turn) I checked that the lifters/pushrods rotated. Turning the engine manually, I found some rotated, some not, and nearly all the lifters had collapsed and I could push on them and feel the spring. Will this cause an issue on startup, or will they just fill with oil and go?
I do not have a proper oil priming tool, I borrowed one last time and the owner of that one is now overseas.

As for the cam, I am not sure what it actually is; it was sold to me as a 350 cam making about 190 hp, it's an original GM unit with some coloured bands on it, and measuring the lift it bottomed out my dial indicator on #1 intake at 10mm (0.393"). Measuring the lobes with a caliper and scribbling on a napkin it should be closer to 0.372"/0.413" on the intake and exhaust valves, so I have no clue frankly. It has no other meaningful markings or numbers neither stamped on the end nor cast into the core itself.

So who has bets on it exploding immediately, sending another round of shrapnel around my crank case? Or that this old cam will be what does it? Or that the diamond-like carbon lifters just chews it up?

 

Hard to say if that matters until it starts up. That's part of the reason for not letting the RPM drop too low during initial startup. I think it's probably safe to guess that you weren't turning the engine by hand at anywhere near 1800 RPM, which is what needs to happen. If the lifters fit more tightly in their bores, it'll take more impetus to break them loose and start them spinning, than you can apply by hand, or even than what occurs at 600 RPM or whatever idle speeds.

Consider what would happen if you put a shaft in a roller bearing that rides directly on the shaft. (ahem, a 10-bolt axle bearing) If the lubricant was "too good", the shaft might spin in the bearing, and the rollers just sit there, and not turn. If that went on for very long, bad things would happen. In the case of flat tappets, if they don't spin on the cam, they start out by wearing a little bar-shaped divot in their face; the cam lobe, since its function is also not working correctly, loses its slight "ramp" shape (the taller side, toward the rear, wears down FAST); and before long, they dig into each other. Once the wear gets severe enough the lifter may spin a little, by accident, maybe even backwards, which is why a wiped-out lifter like yours, usually has a "cup" shape worn into it, rather than a "ditch" although sometimes they do wear that way.

Lifters don't "collapse". See "religion" above. Sometimes the little piddle valve in them leeeeeeeks and they don't hold pressure, butt whatever "collapse" is, it doesn't have any physical mechanical real-world analogs. Don't worry about it.

Sounds like an overly optimistic estimate of ye old 929 cam. .390"/.410", 194°/204°. I can't think of any motors that were "rated" at as much as 190 HP with that cam in them; the most I can recall was 180, butt memory grows dim after a few decades. It was the crappy cam that came in all the crappy 305, 307, 327, 350, & 400 smogger turds all through the 70s.

Not gonna place bets on your outcome. There's too many variables at play here to predict over the Interwebz. Everything from metal chips stuck in the oil passages coming loose and getting flushed into bearings and whatnot, to the lifter bores being damaged by previous wipe-outs, to bad factory machine work to the block that points the lifters somewhere other than straight at the cam. Like I said, "unpredictable". See "religion" above. "I've done all I can do, now it's up to providence". A truly revealing experiment was performed on pigeons that sheds considerable light on this phenomenon, mostly involving the "unpredictability" of events, and the effect it has on creatures such as those who all share this miserable speck of intergalactic dust and ash of ancient exploding stars, including ourselves. Creatures here, it seems, desire to seek out patterns in the events around them, and will invent patterns even if there are actually none.

https://www.all-about-psychology.com...he-pigeon.html
https://cultblender.wordpress.com/20...lled-religion/
https://en.wikipedia.org/wiki/Rorschach_test which it could be argued sometimes applies to those analyzing the responses to subjects under test

I hope you didn't use too much moly grease. It only takes a little to get the job done. I always used to just smear it on the lifters while putting the cam in dry (or with a little oil or transmission fluid on it). Be aware that the moly WILL plug up the oil filter, and next time you tear the engine down, there may be a layer of gray dusty sludge in the bottom of the oil pan, which is the moly particles. If you really slathered it on there, change your oil filter after 100 miles or so, and any time thereafter that the oil pressure seems to fall off for no reason you can determine.

 

"Lifter collapse" I suppose is a term too loosely defined to have a definition and thus should be avoided, however the way I have used it and heard it used is a little as you describe, the lifters little valve leaks and it loses its internal pressure, either it bleeds while on the up-stroke or just from sitting. Furthermore the plunger may stick and the lifter doesn't take up the slack, in catastrophic cases it may stick all the way down or refuse to hold pressure at all and you are pushing just with the lifters internal spring and you could lose valve train control, I've seen pushrods jump up out of the lifter on some diesels.
This is what I imagine by "lifter collapse"- the lifter is "collapsed", or essentially stuck retracted, and functions as a too short solid lifter or it just rides the spring, you may get too much tappet clearance and bad things occur.

As for that cam, what makes it crappy? Whatever this is lifts much more than the stock LG4 cam, but I don't know durations, rates or angles on it, unless it actually is the 929 you speak of.

I used a medium amount of grease, a light coat on every surface. I plan on changing the oil and filter immediately after this break in, as I know there are still shavings of the old cam around, thus I am not too concerned with it plugging the filter in the long-er term. Given that the gods are merciful and I succeed, I will be changing oil and filter often, perhaps every other week with daily driving, to try and prevent rod bearings from showing up in the pan next.
I will be starting it in what should be the american morning hours.

 

Go drive an ORIGINAL 76 Impala with a 350 2-bbl and you'll understand IMMEDIATELY. It's just ... lame. Butt hay, if it's what you've got, it's what you've got.

​​​​​​​Good luck.

 

Comp Cams' rain dance appears to have worked. The oil isn't Volvo 426 mystic silver metallic, and none of the rockers are limp on the deck of the head.
I know this isn't a race cam of any kind, looking at the rockers it's tricky to see which ones are trying to do what, but a slow cam is better than no cam. That will conclude the moral lesson for today.

 

'Glad this time was successful...

 

 

Way too much to read.

Was the cam replaced?

Flushing the engine will not remove all the glitter. You wouldn't believe the amount of metal that can find its way under main and rod bearings through the oil galleries. Changing your oil and filter weekly will not remove all the metal. The engine needs to be stripped down to a bare block and thoroughly cleaned. Its you money because right now you're rolling the dice. How much was the rebuild?

 

Yes, first original for a Howards, then that went flat, and I put in a 350 cam of some variety. $40 from a swap meet, it looked alright, and it's now driven those 5 miles that flattened the Howards without missing a beat.

I know the engine is still full of metal, I know the right thing would be to tear it all down and start again. I'm in $500 with rings, bearings, gaskets, and RTV, then $500 for the cam set (with springs) that went out, springs are still good. Of course not counting labour, which there was a lot of to keep the costs down.

Yesterday I got a second engine, a factory roller block I believe, and will be building that instead while this one probably erodes internally. If it survives for a month and a half that will do, and after I will do an autopsy.

 

Even if you have an older engine, invest in an aftermarket roller cam. My BBC uses a roller cam plus a lot of other high end goodies such as oversized pushrods, shaft mounted rockers etc. I also spin it to 7400 rpm and have close to 0.800" lift which need triple springs to survive. The joys of having a race engine. Never wiped out a cam or lifters but I have broken at least 1 valve spring and caught it before dropping a valve.

 

Yeah nah I'm done with flat tappets. Once burned.
I'm not sure what I'll build out of this, but it'll have a roller for sure, probably EFI. And rigid springs, probably LS6 ones with adapter retainers per sofakingdoms recommendation.

 

I am now on a road trip, so far driven over 200 miles.
It has a lifter tick when cold on intake #3, I removed the valve cover and ensured the lifters and pushrods all rotated. Tightening the rocker seems to quiet it down somewhat. It still lifts and rotates fine but ticks when cold- that is to say almost all the time, as my engine seems to run at 140°F.
Intake #5 however does not tick, but the lifter rotates very slowly in the bore, compared to the others. I pulled it up out of the bore through the pushrod hole with a magnet, it spins freely in the bore, is not mushroomed, or otherwise defective. Lifts just fine like all the others, and makes no noise, it just chooses to rotate very very slowly on the cam. Ideas are appreciated.
Otherwise, it's going beautifully. Due another oil change soon. No sign that it ate a cam last week.

 

Add some Marvel Mystery Oil at your next oil change.
#3 - probably debris in the lifter.
#5 - slow rotation is OK, as long as it rotates.
You're lucky that they all rotate, because using new lifters with a used cam is not supposed to work.
Look at these diagrams. What do you suppose happens to the contact pattern when using a new on a used camshaft lobe?
Answer: NO ROTATION




Look thru here - even if you just look at the pictures: cam wear,articles you need to read | Grumpys Performance Garage

And I'm not trying to discourage you but your pistons might look like this already. You will burn oil if they do.

 

I think you got that backward. You can put new, flat lifters on an old cam....you CAN'T put old, flat lifters on any cam, except for the same lobe of the same cam, that it came from.

 

A used camshaft, where the taper is worn and the lobe is now flat, the point of contact will be right at the center of the crown on the new lifter >>> NO ROTATION.
Some have gotten lucky in the past when doing so, but it is a less than ideal situation.

 

Debris? In my lifter? In my brand new rebuilt engine? With oil that looked like this?

I'm not quite convinced.

I've heard that you can, unless the cam is worn out, put new lifters on a used one, and then do the rain dance. If the lobe has lost its taper then that would be worn out and probably the reason the lifters would require replacement anyways, problems and symptoms.

It seems to have worked, I have done ~600 miles now. I did an oil change and I had to search to find traces of metal.
As for my pistons they looked almost like that when I put them back in anyways so I am not concerned. It doesn't make any undue noise, oil pressure is 30 psi at idle when warm and 45 when cruising, all the lifters rotate as before. I know it is on borrowed time, and that is okay.

After this I might trust it to take me to the grocery store on monday, maybe even to work. I do, in fact, feel lucky.

 

Then in that case, the cam was already doomed with the original lifter on it. NO flat lifter is going to last if it's not rotating. What you're talking about ^there^ is an already failed cam shaft. I was talking about a used cam.

I have put new flat lifters on used flat cams several times, in Chev's Fords and even an AMC....no issues.