The Rodding Roundtable
Motorhead Message Central => Rodder's Roundtable => Topic started by: enjenjo on July 25, 2023, 12:34:01 PM
watch these videos and give me your thoughts
Makes me scared to try breaking in my new lunati . I bought it and the lifters directly from lunati as I thought they would be more careful with the lifters they sent with a cam they are providing warranty on . I hope I am right . The lifter face video has convinced me to check the crown on mine before even using them .
I have watched several videos this year on this. I have a flat tappet camshaft in my 327 chev in my 1948 Simca.. The engine has not turned a lick in 2.5 yrs , so I worry about it even tho the camshaft was fully broekn in and run several passes on the drag strip before its hibernation..
I do not have the $$ to swap over to a retro roller camshaft set up. You have cam , lifters , pushrods to change
I've watched quite a few of these videos, and it seems to be everything. Soft lifters, soft cams, not enough taper on the cam lobes, improperly ground lifter faces, too much or too little lifter clearance to the bore, too much clearance between the plunger and the lifter body...anything. Someone can make a very rational argument, with evidence, for any of those things. No wonder there seems to be an epidemic of failed cams, and builders who control for one thing get bitten by something else. The lifter faces in that bottom video, though, when the light hits them it looks like a geodesic dome, a whole bunch of flat faces instead of a smooth face.
Had this realization around 2007. The curtain done fell on the flat tappet show a long time ago. Seems like a business opportunity where someone would step up with good lifters but that doesn't happen because money. If the cost of a make-do hit-or-miss brand fits ten times inside the price of a sure-fire top-notch brand... of air drill, speaking in my terms, I'll take my chances on having to buy ten drills. Everybody does. Thats the issue but not the only one. Waning interest / demand. Racing isn't a household word anymore and design advancements left lope lovers in the dust. Them engine guys are swallowing some hard nasty facts. I chose bodywork but nowadays the technology is nonsensical beyond comprehension for collision guys. The USS Flat Tappet is sinking. Mine were not lookin good a couple years back.
My take is we are on borrowed time, pretty much.
i pulled the lunati cam out of my rambler a couple of weeks ago, looked like new. replaced it with a Mellings RV cam and broke it in with rotella T1 and mellings cam lube...fwiw
What might be interesting to see is a comparison of machining precision on flat tappet vs roller lifters made at the same plant.
Would it mean anything if proper dimensions with less variation were found on the roller product?
A manufacturer's assumption must be that a buyer wants only the least expensive version of a product which in a picture appears to be like the desired item. (actual product may vary)
Is anyone asking these overseas plant managers or whatever if, for a higher price, a usable quality level product could be made available? Could it be as simple as not knowing the right sentence in a foreign language?
Could we pay half again more but not go roller for a stock smoggo build? Roller conversion was presented to me as an only option for a Pontiac that one might realistically put a hundred thousand miles on a decade ago.
Thats the while root meaning of I drive junk. There has to be a camshaft and it has to be the modern kind or stay home.
Interesting comments, Matt, as usual. It reminds me that General Electric at one time intended to close all their operations at Appliance Park, Kentucky. That was the high point of manufacturing being outsourced from the USA. It didn't work out that way.
What they discovered is that some things lend themselves to outsourcing far more than others. Low tech products which don't require extreme precision, absolutely. What they didn't have luck with was products which require much skilled work, great precision, very tight controls on material quality, or were in active development with frequent spec changes.
It wasn't just about availability of skilled workers, because the USA certainly isn't the only place in the world where people are capable of excellent craftsmanship. The more important thing was communication. When engineers and quality control experts have to communicate to factory managers 13,000 miles away, in a different language, with 12hrs time zone differential more or less, quality suffers.
Whatcha wanna bet theres a slippery coating solution for this that will never be explored. Theres such thing as piston skirt anti-scuff coatings. Nitriding is best left to HF drill bits that wouldn't make the first hole without it.
Aren't computer controlled electronic or hydraulic valve actuators already a reality? Direct injection is.
Again, money twarts efforts. First generation V8s are not given the advantageous design attention. Because while it may take decades more for users to admit obsolesence, manufacturers know that the dead horse won't suddenly snap to life and win races no matter how much whipping is done.
I have to wonder if some sort of anti-friction coating on the cam lobes or lifter faces would help. It could help keep the lifter and lobe from digging into each other until the parts work harden sufficiently to be operational. It could lower friction until the lifter fails to rotate and makes the problem worse. It may prevent oil from getting into the tiny crevices of the metal and cause problems that way. I sure don't have the technical expertise to know.
I'm devoid of that as well. :)
The jist of what I caught onto was that it is less about materials than dimensions.
I assume methods exist for truing / sleeving lifter bores in tired blocks and that that is a contributing issue with antique castings that will never improve.
Heres one for our residents who know their way around a machine shop:
If a guy was to take a set of common oh, say $300 flat tappet lifters, take .125 off the faces and install (thats my question, how to install) precisely machined caps on the faces, and could sell those for under $600 and consistently create lovely break in patterns when used in a fresh block or checked and corrected seasoned block's lifter bores... might that be a thing?
Tackling that manufacturing step here might allow adequate QC of lifter faces while using existing overseas castings. There may not be .125 of meat on existing faces so a body casting revision might be needed.
Lobes are one thing to worry about but the nitty gritty of what goes on at lifter to lobe interface that the guy in second vid explained has me thinking just about the lifter faces. Seems like thats what it boils down to. So make perfect faces, attach to milled down plain lifters, and if the caps didn't create other issues that'd be half the battle. Double the price but thats half of a roller conversion.
Just meandering thoughts that I am certain have entered minds of those who make livings on engines.
This link has some interesting thoughts on it. There's been a lot of attention paid to metallurgy, but what if it's other changes to engine parts? Cam lobes have higher ramp angles now, even when the measured timing remains the same. Spring pressures are higher now, and more consistent. higher rocker ratios present higher pressure at the cam lobe.
But what about failures with stock replacement parts? Again, I don't know. Maybe these stock replacements have been massaged in ways that don't quite show up in the specs? More aggressive ramp angles are so common now, maybe they're being incorporated in stock replacements. A lot of stock performance engines, like the Ford 5.0 HO engines from Fox bodied Mustangs suffered premature valve float which can be remedied with more spring pressure. Maybe some of these changes are in the "stock replacement" boxes?
https://www.camcraftcams.com/some-thoughts-on-cam-and-lifter-wear/
My random thoughts on the oil , lifter , camshaft wear :
When oil specs reduced the ZZDP and related additives for the catlytic converters... OEM manufacturers wwent to roller camshafts.
Us olde pharts with flat tappet camshafts started using ZZDP additives, diesel oils , specialty oils, etc. THings seemed fine till: It appears the camshaft - lifter manufacturers forgot how to build flat tappet cams and lifters?
Decades ago, when I broke in a new flat tappet camshaft.. I coated the lifter base and cam with the thick goo like everybody did. I also used a GM oil additive called EOS aka Engine Oil Supplement.
So: what happened?
8)
I have 2 thoughts to add to this: the 1st is about 5.0 engines. When I put my 32 together, I used LS springs. In talking to the Ford Performance people and telling them how high it would rev, they were surprised. The stock springs are good for around 4300 rpm. I believe that is about friction loss and cafe fuel milage. The 2nd: are all lifters the same. Absolutely not. I have some NOS lifters for a sbf. If you measure the crown on them, it's very obvious what is there. When you take the white box units and compare, you will notice the difference. There's so many factors involved in this that I don't think you will find one problem. I'm aware that there are way more failures than when I was young. I wonder if we used the same parts from 50 years ago and used today's oils and additives if we would get different results????
I have read about people sending out OLD lifters to get them re ground as they do not trust the metallurgy of the new stuff. Looking at the video of the guy grinding down lifter faces it is obvious there is a problem with the contour of the face . I wonder if it is being done on a machine that is not adequate for producing the proper contour . Many years ago I had projects where I had to dress a specific radius into a grinding wheel with a diamond dresser set to that radius . I would then surface grind that contour into hardened steel parts . I wonder if this could be done in a valve re facing set up . One problem with that would be dressing the stone to the right radius .
That ^^^ is why my thought is to cap run of the mill lifters with precisely made face wafers. Thick enough that the radius is fully included on the precise piece. Obviously a proper lifter face is a lost art so adequate quality is no longer available. Ceased to exist. Maybe in 7 or 800 years we will discover how again. Like with Ulfberht swords.
Seriously the solution is probably not unlike what Leno did just to drive a Sprint6 Firebird around a little... redesigned and re-engineered and made a dozen custom maybe cnc billet cam followers. Because the originals weren't good enough and aren't available.
Like when you go to Peru and the most astonishing masonry is at the bottom of walls. Them who came before us were better at some things. People die, knowledge is lost. Like how to make lifters.
So are these old news? Require using Snake Oil, maybe?
https://www.compcams.com/high-energy-dlc-hydraulic-flat-lifters-for-chevrolet-small-and-big-block.html
Someone commented that lifter/camshaft dimension, clearance and compatibility is a lost black art.
Not so yet. There are many shops across the country that still know how to do it right with the right parts.
You just have to seek them out. You also have to educate your self on what works for the application you seek.
Pick people that have ACTUALLY DONE THE WORK and have raced and won, to research. If they have an engineering background, that helps.
I didn't look at the video because I have seen it all over the 71 years I have been in the cam business.
When collecting parts for a build, stay with USA made parts that have a known reputation of success.
If nothing is available, find out what others are using and if it is working 100%. Sometimes you have to do it yourself.
When it comes to hydraulic lifters I can say I have never had one fail. That is because I have never built an engine with them in it.
Hydraulic lifters CAN be reconditioned. Candidates for reconditioning should be selected carefully. The face should be smooth, shiny and with no lines, marks or noticeable wear pattern. The body should be checked for diameter within spec. When assembling the engine, the lifter to bore clearance should be checked carefully.
The internals should be CAREFULLY checked for wear.
The face should be checked for hardness and should be at least 55 Rockwell C.
The face should be reground with .0002 taper. This is a TAPER, NOT A RADIUS as some people think. If you think about this, if it was a radius you would have a pinpoint contact area and the unit pressure would be extremely high resulting in almost immediate failure.
The taper on lifters and cams will vary slightly between OEM manufacturer's but .0002 will work ok.
An easy way to check this is put 2 lifters together face to face and rock them. If you can see light at the edge it will be ok.
After market offshore cast iron cam cores are noted for very poor heat treat. Hard spots and some spots dead soft.
If a soft spot is on a lobe nose, failure will be soon. Likewise for the gear area.
Some 49 to 53 flathead Ford cam cores had this problem.
Very few cam grinders ever checked this.
USA manufacturer's haven't all been lily white over the years
but for the most part when they had a problem it was fixed quickly.
In late 1956 Ford put out a factory bulletin to all dealers that they expected in excess of 3% of all cams in 1957 312 engines to fail within 500 miles due to lobe wear. (bad heat treat)
Their estimate was pretty close. There was never any info release on why this happened.
To the person that suggested a hard face material on lifters, it has already been tried but found not necessary and WAY too expensive for production use. John Deere tried facing lifters with carbide for awhile. While they would last forever, it was just too expensive to do.
Are there any US based flat tappet hydraulic manufacturers left?
It sounds like most of these failures are from off-shore companies, that sell through Summit, other online outlets. And mainly the failures seem to be via bad machining, wrong crown angle etc. Not hardness failures.
This article provides some insight on flat tappet cams.
https://www.chevyhardcore.com/tech-stories/engine/tricks-to-increase-the-quality-of-life-for-flat-tappet-camshafts/
That's one of the best articles I've seen on the topic.
Thanks for the link 8) 8)
As usual in tech articles. Some good info, some bad info, some left out.
They barely touched on the MAIN reason lifters rotate, lobe offset to centerline of lifter.
They mentioned shimming the cam fore and aft..That can get 1 or 2 rotating but screw up others in the process. Sometimes a new block is called for.
A LARGE percentage of cam lobe failures are due to poor production process. Most production cores are induction hardened. If the process is not done absolutely perfect the hardness will NOT be consistent throughout the length of the core. Some areas will be as they should be, some will be rock hard and others will be dead soft. A good example of this is the flathead Ford cams up to 1948. They were excellent. 1949 to 1953, not so much.
They talk like chilled iron lifters are a recent breakthrough.. Isky had them in the 50's.
Pressure oiling the lifter face is nothing new either.
Think about the millions of engines over the years that ran their total expected life with no problems. The small percentage of early failures due to cam and lifter problems are the ones you hear about though. Makes ya wonder if they were end of shift type or maybe cutting corners type or just done at home with used parts type.
In any event it is good tech articles like this that keep up my interest in gardening.
I'd say that induction hardening is a strong suspect in the failure problem along with improperly machined lifter faces. Shows that there are "experts" everywhere, and you can't necessarily believe those who claim to be experts.
I'm no expert, but I've said my share of things that just aren't right. On the other hand, I've seen multiple people who claim to be experts say there's no way it can be a soft lobe, because they're all ground from the same blank. That includes a guy who does YouTube videos now with a Mopar focus, but once wrote magazine articles with a drag racing focus and was very active in the AHRA.
Here are a couple of links I found about camshaft hardening. They confirm that the faces are hardened further after grinding to avoid brittleness.
https://patents.google.com/patent/US4720311A/en
https://performancewholesale.com.au/blogs/news/camshaft-heat-treatment-explained
https://www.roadandtrack.com/car-culture/a33179/the-secret-story-of-tuckers-failed-massive-engine/