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Discussion Starter · #1 ·
I saw this article in Engine Builder Mag and thought maybe you guys know this already and may be not. Want to give credit to Engine Builder Shop solutions and to Norm Johns.


Along with the use of assembly lubes, break-in oils with ZDDP (Zinc Dialkyl Dithiosphate), and a lifter bore grooving tool our shop does this; on all flat tappet cam engines our shop has added one step before final assembly.

With the block in a bare and clean state we’ll put in the two end cam bearings and install the cam with only light oil. Next we install the lifters with only light oil. Install a bolt in the front of the cam and spin it quickly clockwise with a speed handle and observe each lifter’s spinning action when the engine is running. You can use a felt pen to mark the lifters so it’s easier to see them spinning. If you find any of the lifters not spinning, this could be a potential problem if it leaves your shop like that. Lifter bore or even cam bore alignment could be the problem.

Many times the cam bearing bores get closer (fall) towards the crank centerline going front to back, (especially on BB Chevys) which in turn causes the taper on the cam lobe to be lessened towards the back of the motor. Zero or too little taper can keep the lifter from spinning, and this can cause the cam to fail shortly after fire-up.

To remedy this problem without reboring lifter or cam bores check local listings or the internet under custom cam grinding to have the cam reground with more taper grind into the lobes. After regrinding we do the test again. We’ve had great luck and no flat cams when all of the lifters spin before we fully assemble the engine, even with today’s lousy oils! Yes this will cost more, but what will really cost more – an extra cam grind, or a flat cam, or a comeback and angry customer? Thanks and good luck.
 

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flat cam

My room mate in college rebuilt his Ford Fe and the cam went flat in 100 miles, he pulled it apart at their farm shop and got another new cam from the dealer and it went flat again in about 100 miles. I went to his house for weekend to help and found that the cam was catching two lifters with the same lobe. Factory replacement cam and original block, it only got new rings and bearings the first rebuild. I ended up getting a transmission thrust washer from a box of spare pieces the dealer had in their parts room, and every since then I drop in one lifter at a time and rotate tthe cam to check.
 

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I saw this article in Engine Builder Mag and thought maybe you guys know this already and may be not. Want to give credit to Engine Builder Shop solutions and to Norm Johns.


Along with the use of assembly lubes, break-in oils with ZDDP (Zinc Dialkyl Dithiosphate), and a lifter bore grooving tool our shop does this; on all flat tappet cam engines our shop has added one step before final assembly.

With the block in a bare and clean state we’ll put in the two end cam bearings and install the cam with only light oil. Next we install the lifters with only light oil. Install a bolt in the front of the cam and spin it quickly clockwise with a speed handle and observe each lifter’s spinning action when the engine is running. You can use a felt pen to mark the lifters so it’s easier to see them spinning. If you find any of the lifters not spinning, this could be a potential problem if it leaves your shop like that. Lifter bore or even cam bore alignment could be the problem.

Many times the cam bearing bores get closer (fall) towards the crank centerline going front to back, (especially on BB Chevys) which in turn causes the taper on the cam lobe to be lessened towards the back of the motor. Zero or too little taper can keep the lifter from spinning, and this can cause the cam to fail shortly after fire-up.

To remedy this problem without reboring lifter or cam bores check local listings or the internet under custom cam grinding to have the cam reground with more taper grind into the lobes. After regrinding we do the test again. We’ve had great luck and no flat cams when all of the lifters spin before we fully assemble the engine, even with today’s lousy oils! Yes this will cost more, but what will really cost more – an extra cam grind, or a flat cam, or a comeback and angry customer? Thanks and good luck.
It's looking like the days of running a flat tappet cam, on the street at least, are about closed. Around the Seattle area it's getting increasingly difficult to find heavier weight oils including 15-40 and 20-50 as the EPA wants all the ZDDP carrying oil off the market plus these new engines use very light weight oils with no ZDDP. We just put in a supply of 15-40 DELVIC cause our local distributor says when that's gone boys there ain't gonna be any more.

I'm thinking the race sanctioning bodies are going to very shortly have to rethink their ban on roller lifter cams as well. I guess the 60's truly are over.

I have for decades used a cam button on Chevy flat tappet cams, I feel the lobe and lifter, as well as the distributor gear have plenty enough to do without also holding the cam in the block. The two things that come out of this is that we hardly ever experience wiped lobes and lifters even with today's low ZDDP oils while the so called spark scatter problem even with the 7 tooth SBC oil pump is mostly gone. We, also, do not use oil restrictors even with solids and we use standoff vents rather than closing the drain back holes in the valley along the cam. This does shut off the mid block drain back from raining on the crank while allowing some breathing space so all the blow by isn't trying to get into the valley on the ends where I'm also trying to get the drain back oil to drop into the pan.

Bogie
 

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Most cams factory oem and aftermarket are made by Camshaft Machine Corperation in michigan. They are top quality manufacturer of cams. Most bad grinds come from old templates and in house ground cams. Not sure about the lifters but they usally fail and wipe out the cam. For most cases of failure its either inproper installation or bad lifters. Possibly before and after the heat treatment.

Since they are mostly cnc ground. Its kind of hard to convince your cnc not to do what its told. They are also scanned with lasers to make sure grind was correct. This is the same process and companies that ford and chevy use.

that being said there is alot of junk out there. With a big lathe and some skill you can make your own cams. Regrinds are even easier. And alot more common than you may think. This where you get into trouble.

Isky is a great cam but i bet they make just as many bad ones as anyone else. But they do alot of quaility control to make sure they never reach the public. And that makes a world off diference. I did not see anything on isky site saying they make them in house. But that is fine.

there is so much misinformation in this post, I'm not even sure where to start.
isky, comp, bullet, elgin, erson, crane. that's a large amount of the aftermarket and they are NOT ground at that place. and I'm not even mentioning any of the smaller custom grinders that do their own in house. not saying anything bad about it, but they certainly don't grind cams for these places.
next, you cannot, no way, not physically possible, make a camshaft on a lathe.
i have been a machinist for many years, run everything from small lathes to
mills bigger than a house, and a lathe simply can't make a cam. maybe you could rough one out, but without getting into the technical aspects of it, it just can't be done.
and just to clarify, isky does manufacture in house, and is among the top cams out there.
they all have issues, any manufactured part will to some extent, but their stuff is top quality and i see very few issues with them.
 

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My engines have never had a cam go flat. Never use assembly lube just 30wt oil. Prime good while rotated and have a break in procedure. The thick pastes might impede the lifter rotation and cause the failures I read about. There is alot happening and the hobbies regulating itself, slowing to a standard. Hydraulic flat tappets are long term and not going anywhere.

Nothing i build sees more than 5500rpm, and not per say, raced.

Flat hydraulic cams from edelbrock, comp and lunati have beem my choice. Almost always staying under .500" cam lift and racing high seat spring pressures. That could have something to do with the margin for error.
 

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My engines have never had a cam go flat. Never use assembly lube just 30wt oil. Prime good while rotated and have a break in procedure. The thick pastes might impede the lifter rotation and cause the failures I read about. There is alot happening and the hobbies regulating itself, slowing to a standard. Hydraulic flat tappets are long term and not going anywhere.

Nothing i build sees more than 5500rpm, and not per say, raced.

Flat hydraulic cams from edelbrock, comp and lunati have beem my choice. Almost always staying under .500" cam lift and racing high seat spring pressures. That could have something to do with the margin for error.
You must be living in an alternate universe, the SBC has had so much trouble with wiped lobes/lifters it became the foundation of a class action law suit which the consumers lost to GM but never-the-less it was a huge problem up till GM started using roller cams in car engines in 86 and they neutered the truck cams to very low lifts less than .4 inch and durations of less than 170 degrees till the roller Vortec came on line in 96 with baby buggy valve springs to reduce the load between the lobe and lifter.

Bogie
 

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Discussion Starter · #8 ·
There are shops that turn down jobs that are not rollers. With the potential of customers bad mouthing the shop and the losses due to comebacks,it just isn't profitable to do flat tappets.
 

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CMC DOES grind most of the flat-tappet hydraulic cams ground in the USA today. Comp AND Lunati have told me this. CMC was the main "vendor" to the car companies prior to the advent of rollers. It made perfect "sense" to use their equipment. Comp, Crower, Lunati, etc. (the "big" cam companies) own their own "masters" and CMC uses them for propietary grinds (like XE and VooDoo). Most of the generi-grinds (Elgin, Wolverine, Edelbrock...) are "re-hashes" from older grinds.

There are MANY applications for flat-tappet hydraulics. We still sell a bunch. The cost of rollers runs many people away. Pop had a "saying" that fits here. "When all else fails, follow instructions!" If one were to follow specifically, the instructions for "break-in" provided by Comp, Crower, Lunati, etc., most "flat lobes" wouldn't have happened. Excessive spring pressure is another cause. Many believe you "need" more spring than you really do...

FWIW

Jim
 

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You must be living in an alternate universe, the SBC has had so much trouble with wiped lobes/lifters it became the foundation of a class action law suit which the consumers lost to GM but never-the-less it was a huge problem up till GM started using roller cams in car engines in 86 and they neutered the truck cams to very low lifts less than .4 inch and durations of less than 170 degrees till the roller Vortec came on line in 96 with baby buggy valve springs to reduce the load between the lobe and lifter.

Bogie
I vividly remember my father and uncles replacing several broomstick cams in 307s; that and the plastic geared "silent running" timing sets used to drive people nuts around here
 

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fe cam isues

My room mate in college rebuilt his Ford Fe and the cam went flat in 100 miles, he pulled it apart at their farm shop and got another new cam from the dealer and it went flat again in about 100 miles. I went to his house for weekend to help and found that the cam was catching two lifters with the same lobe. Factory replacement cam and original block, it only got new rings and bearings the first rebuild. I ended up getting a transmission thrust washer from a box of spare pieces the dealer had in their parts room, and every since then I drop in one lifter at a time and rotate tthe cam to check.
if the engine is 1963 and older it should have a spring and buton on the end,had a simler isue and builder had left them out.1964 and up have a thrusr plate and a diferent gear that holds the cam in place.pre 64 fes can be easly converted as hard to find the spring and button as well as clip'i have 1 left cliff
 

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My room mate in college rebuilt his Ford Fe and the cam went flat in 100 miles, he pulled it apart at their farm shop and got another new cam from the dealer and it went flat again in about 100 miles. I went to his house for weekend to help and found that the cam was catching two lifters with the same lobe. Factory replacement cam and original block, it only got new rings and bearings the first rebuild. I ended up getting a transmission thrust washer from a box of spare pieces the dealer had in their parts room, and every since then I drop in one lifter at a time and rotate tthe cam to check.
That would be true of the early FE's, they came from the factory with a thrust button that had to go back in or the cam would jump around to where lobes could catch multiple lifters, another common error is to get the cam tunnel plug behind the flywheel/flexplate too deep which will hold the cam forward enough to where lobes are lifting multiple lifters. Ford finally learned its lesson and put thrust plates into the engine about the 1963-1/2 model when they used to do a lot of mid model year updates.

Bogie
 

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fe cams

That would be true of the early FE's, they came from the factory with a thrust button that had to go back in or the cam would jump around to where lobes could catch multiple lifters, another common error is to get the cam tunnel plug behind the flywheel/flexplate too deep which will hold the cam forward enough to where lobes are lifting multiple lifters. Ford finally learned its lesson and put thrust plates into the engine about the 1963-1/2 model when they used to do a lot of mid model year updates.

Bogie
the rear cam corplug actually is a specel plug and it goes in backwerds to the normal core plug. some service manuals mention installing this plug corectley
 

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I have always wondered if wiping cam lobes is a modern phenomenon, due specifically to modern oils or if it was always a problem, even back in the heyday of the muscle car era.

I'd imagine the risk was always present, but was less to worry about back then. Is the problem mainly that we are using cam's with very aggressive ramp rates, high lift, and heavy springs in the presence of "bad oil"?
 

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Discussion Starter · #15 ·
We wouldn't build flat tappet engines for customers anymore. But back when we where,we told customers to use the oil additive for the entire life of the engine,not just for break-in.
 

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But what about back in the days before there was engine oil additive? Back when the oil was good enough as is. How great was the danger of wiping cam lobes back then?
It happened, but back in the '50s-'60s and into the '70s, the cam action was much more gentle than the ramps seen on today's fast acting cams like the XE and Voodoo series. Even the 'hot' solid cams were- for the most part- not very radical as far as lift to degrees of cam rotation went. The factory production high performance Chevy cams all the way up to the solid cams all used basically the same valve springs. All this kept the cams from wearing rapidly, and cam failures weren't as frequent as today- or so it would appear. And there were always additives and cam break in lube, at least when I was aware of it in the '60s.

So I think there were less failures back then, but that could be an illusion. When we consider the number of aftermarket cams installed today w/the number sold back when- and add the transparency of the internet drawing attention to the failures today, IMHO there's good reason to wonder if the percentage of failures per thousand, say, were that much different.

FWIW, during the '70s there was a rash of bad factory Chevy cams, IIRC due to bad hardening/surface treatment. This would have caused problems regardless of the additives. More recently, offshore lifters have compounded the problem. No amount of additives or careful break in will overcome a badly made part.
 

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It happened, but back in the '50s-'60s and into the '70s, the cam action was much more gentle than the ramps seen on today's fast acting cams like the XE and Voodoo series. Even the 'hot' solid cams were- for the most part- not very radical as far as lift to degrees of cam rotation went. The factory production high performance Chevy cams all the way up to the solid cams all used basically the same valve springs. All this kept the cams from wearing rapidly, and cam failures weren't as frequent as today- or so it would appear.

But when we consider the number of aftermarket cams installed today w/the number sold back when- and add the transparency of the internet drawing attention to the failures today, IMHO there's good reason to wonder if the percentage of failures per thousand, say, were that much different.

FWIW, during the '70s there was a rash of bad factory Chevy cams, IIRC due to bad hardening/surface treatment. This would have caused problems regardless of the additives. More recently, offshore lifters have compounded the problem. No amount of additives or careful break in will overcome a badly made part.
I agree with everything here; but would like to add that I wonder how many cam failures are misdiagnosed by people who aren't versed in actual diagnosis of 50yr old engine technology
 

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I agree with everything here; but would like to add that I wonder how many cam failures are misdiagnosed by people who aren't versed in actual diagnosis of 50yr old engine technology
auto gear is on the right track.also after talking to a camgrinder in the vancouver aria tells me that the cores for most grinders come from china and ar of poor quality to be polite. he also claims that gm engines make matters worse where there
is no positive controle of the cam wandering back and forth.
so combine autogears coments with poor cores,you have room for high failure rates.
then you add the oil and the high spring pressure radical grinds,a roller cam sure improves the ods. finally 90% of thes engines never hit the track and ar just for street use,some should cross a couple of plug wires for the sound. cliff
 

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I have always wondered if wiping cam lobes is a modern phenomenon, due specifically to modern oils or if it was always a problem, even back in the heyday of the muscle car era.

I'd imagine the risk was always present, but was less to worry about back then. Is the problem mainly that we are using cam's with very aggressive ramp rates, high lift, and heavy springs in the presence of "bad oil"?
Actually if you go back and look at the cams used in the muscle cars, they tend to have a lot of duration and not a lot of lift. Then when you look at the .050 inch duration numbers you see that they have a huge amount of ramp in their total duration. GM tried to deal with the lifter lobe wear problem by Parkerizing the cam which is a phosphate conversion coating on steel used to harden the surface and provide some innate lubricity to the parent material. For you guys who are interested in guns this will have a very familiar sound to it as it is a common process to protect gun parts from corrosion and wear.

Going back to the days of the flat head which also had an appetite for camshafts the popular treatment at that time was chilled iron. This is a process that takes white cast iron and uses heating and cooling to create a soft core with what essentially is a nodular iron surface for better wear. This was the "Cat's Meow" back in the day for a long wearing set of cam and lifters.

The roller cam follower has been around for a very long time. The problem with the flat tappet cam and lifter is the one where you cannot have sliding contact even with lubrication in some cases of same/similar metals otherwise you get surface welding (galling). So where rubbing contact is concerned either the metals need to be a lot different with lubrication and or with different harnesses or wear coatings. For flat tappet camshafts this usually meant cast iron with conversion coatings like Parkerizing and or heat treatments like chilling, or a contact patch of steel on an otherwise cast part. A rolling contact between similar materials is much less prone to galling and will function quite well with just common oils or grease for lubrication. In the case of lifters and cams roller contact also allows the use of more aggressive lobe profiles as the design limit of the flat tappet is where the lobe is so aggressive the lifter edge would dig into it. This is not a problem with roller contact; the limit here becomes how much side load the lift rate puts into the lifter body which wants to jam it in its bore.

Cost is a predominate issue with the auto manufacturers; one has to realize that to a large extent cost containment is a business’s predominate driver. Sort of a race to the bottom. The theory is that creative minds will find technical solutions that are both cost and performance effective so things will get better while costing less. Sometimes this works sometimes it doesn't but that's blather for college econ classes. Aircraft engines certainly went to roller cam followers very early in the 20th century for the need to use aggressive lobe designs without the wear issues so steel was used for cams and the lifters became steel rollers on steel needle bearings. Harley Davidson has used roller tappets as far back as I can track into very early in the 20th century and I'm sure there are many other examples. Detroit ever cost conscious used the flat tappet forever which had the back side of developing lubrication technology that allowed the use of increasingly aggressive lobe profiles and stiffer springs but there was always a limit to this. The performance aftermarket developed roller cams and lifters back in the 1950s for production engines to get into the power available in more aggressive lobe profiles and lift rates, but these were and are expensive. Detroit had to figure out a cost contained solution to cam and lifter life as the EPA informed them that ZDDP as an oil additive would have to be discontinued. They went through a period of materials development starting with machined steel, going to cast steel with treatments and finally arriving at specialty alloy cast irons with wear treatments for the cam and low cost lifters with simplified roller systems. These are a lot different from race roller cams and lifters and you will get them into design limit trouble pretty fast if you use this stuff on a highly built performance engine.

Bogie
 
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