BRM cam's to choose from... Lets discuss

[IndigoBlueWagon]

Pete, we seem to be jousting semantics. The whole point of a cam that creates better economy in a diesel is also one that, by extracting more energy from the fuel, IS more power. Quite simply, the project would have to be screwed up real bad for a .020" taller lift cam with more duration at the cam peak to LOSE power. The main purpose was to avoid the wear issue. Secondary interest was to create a by-product of performance enhancement.

Not semantics. The OP asked what power gains could be expected from an aftermarket cam, and I wrote that there isn't data. You confirmed that. Better FE is not more HP or torque. And many people selling aftermarket cams (maybe you, too, but I'm not sure of it) claim that their cams increase power. All I was saying is there is no proof.

 

[Franko6]

Well, we all agree, to a point. We are like blind men looking at an elephant...

I get the drive-in's for maintenance, but it's not really a daily occurance. We see broken stuff every single day, shipped in from every corner of the US, Canada, and a few further flung then that. When they are calling me, it's not MAINTENANCE. The reason we are calling the ball with a cam worn about .006" -.008" is that first, it doesn't stop at that and the wear is not arithmetic progression, but compound. Second, like it or not, there is still a usable and rebuildable cam if it doesn't get below 4.424". We can use them to good purpose. However, to calm everyone's nerves, they are far and few between and virtually all the cams we use are new.

Once the wear starts, it progresses geometrically. We have had cams that mechanics guessed would last another 20,000 to the next timing belt and blew a hole in the lifter in 10k. It's not an exact science.

But when you can look under the lifters and see the concave dish in them, it's time for them to go. We all will agree with that. The oil pump is then another issue, as this partly being an oiling issue, a worn oil pump is a problem and has to be inspected.

We see some interesting ETKA parts that nobody in the VW world talks much about. For example, additional oil cooling, water cooling, transmission cooling that is in their parts listings. Maybe if we are in 'problem' parts of the world, where it gets hot, maybe we should be upgrading some of that stuff for more life-expectancy.

 

[Franko6]

We disagree, Pete. We are always being told what we "can't do... shouldn't do... haven't done.... should have done... for several years, people were telling us 'you can't rebuild a TDI cylinder head. I'm going have to tell a few thousand people their cylinder heads aren't working... Now we are doing it with cams.

We found a bonified problem. Cam engineers we talk to agree with us. Even comments, "I don't understand what they were thinking"... from cam designers. You can talk all the way around the circle, but you can't fight our successful innovation's track record. We've even been called out for 'parroting' what our cam engineer says. What am I going to tell a guy with 56 years of diesel cam engineering under his belt? That is our cam designer. Tell him what you think.

As many cams as we have installed, many of them with better performance than before... INCLUDING improved FE performance. You can disagree, but improved efficiency equates to an overall improvement in performance horsepower AND THAT WAS NOT PARTICULARLY OUR GOAL.

Our goal is to get improvements in fuel economy, longevity. Horsepower should come with a warning sticker... you can damage these heads and crack them with a stock cam. Perhaps you should better call what we have done 'Optimizing', as the cam does cause a known and marked decrease in EGT's. It's certainly not a bad thing.

Lastly, we are also replacing those aftermarket stock cams that were sold to replace worn out OEM cam. There is a quote that starts..."When you do the same thing, expecting different results...". I bet you know the rest.

 

[IndigoBlueWagon]

Frank, all I've written is that there isn't any data that shows any aftermarket cams make more HP and torque than stock cams. That's all. And you've agreed that you don't have data to show they're a power improvement. In fact you said you wouldn't want to gather that data.

I've got no agenda except to help point out to the OP that claims that anyone here makes regarding power improvements with aftermarket PD cams don't have data to back them up. This is not a matter of agreeing or not agreeing, but a fact that the data doesn't exist. I have no interest in making more power in a PD, the OP was wondering if a cam would help it do that. I don't even own a PD, unless you count the BKD engine in my garage.

I'm not arguing about FE, even though I've not seen any hard data on that, either, and I don't know how you'd objectively collect it.

 

[James & Son]

OEM VW: Terrible idea and will wear out again

Unfortunately the OP did say this as a given. Now where did he get this from. I have never heard anyone say they are on there third cam except some very early examples, A5Inky and Jnitrofish. But I say when Ina got there black coating on the followers shorted out the life expectancy of the follower went up 50,000 to 100,000 miles. This is why no third cams yet. Frank just said he starting to see the early OEM replacements now coming in. Well next he will be seeing some sorted( colt and franko) cams coming in as well.

Indigobluewagon indicates 200,000 miles average for a stock cam. I say more like 150,000 is average. Now add on 50,000 for your next cam life expectancy and your car will have 350,000 miles on it before its third cam. I am talking averages here.

 

[bobthefarmer]

Cam Bearings? Don't need replacement?

That's the weird thing about those cam bearings... first, that they even thought to put them there at all (most OHC engines, including all other VAG engines, don't have them), but also the fact that they all seem to wear the exact same way, and only to a certain point, and then pretty much stop.
Seriously, I've looked at cam bearings that had 30k miles on them, and ones that had 280k miles on them, and everything inbetween: they look the same. Strange.

So are you saying that at 160k Miles, when I do the 2nd timing belt change, I should just inspect my original cam and push on (without doing cam bearings)? I have thought about starting a used oil analysis (from 130-160K) just to see if I can anticipate a cam failure. My mileage is down by 5-10%, but car seems to be performing well. I can never tell if I am just hyper paranoid or lazy. My 125K 2006.5 BRM is doing just fine for me. I want to be prepared for an upgrade cam, but I'm not willing to crank open the wallet early and do a precautionary upgrade. I hate setting a Hard Time Maintenance. There are too many variables for that. But I stand behind using the correct oil, without any additives.

 

[bobthefarmer]

Where did this information come from? I find a wear limit of .15mm (sorry, I don't speak 'inches') in Alldata, and that is for axial play (the only dimension given).

I speak mm and inches. .15 mm = (.15 / 25.4) = 0.006 inches.

So Franko6's value was correct for 0.006 loss on the Lobe measurements (worn 2.424 vs stock 2.430/2.432 inches). Axial Play is a comparative measurement to Lobe losses. It would have a similar effect in cam performance as the cam would not open the valves to the same amount as if it would when stock and unworn.

I could be talked into a dyno comparison. I'm at 125K miles and had the timing belt changed @80k with no visual cam problems (i did not change bearings nor look at them). I live in a southern climate (bad). I would be willing to invest in this challenge. I'll give my car for a week. Let's set the stakes for this dual. Of course I would pay for T/B, Cam and Bearings. I'd be willing to pay labor, and share the dyno cost. I would love to measure my current cams to see if my engine would qualify for a apples-apples comparison. I would likely be doing that Pre-Cam measurement myself, but I would want the Cam Manufacturer to be performing the upgrade, such that I could not influence the end product. I would be willing to invest for the longevity that Frank talks of.

Who want's to jump into this for Colt?

I do not drive a Tdi for power, it is an economical tool for me that I enjoy.

Who is the other aftermarket guy and is someone ready to pony up there?

 

[James & Son]

I am not going to try to figure out what oilhammer ment, but my hard cover bentley states the following which seems to make sense.
"Check radial clearance with plastigage, wear limit, 0.11mm(.0043 in.)"
"Max. runout:0.01mm (.0004 in.)

Anyways your the man Bob for offering.

Edit : actually, the term runout is incorrect if they are referring to axial play( axial play is in a back and forth direction of the axis). Runout usually refers to axial mis-alignment or an example is clocking each main bearing to see if their in alignment to one another.

Edit2; radial runout max. .0043"
axial runout max. .0004"
This for the cam bearings. Runout is a general term i guess and you need to verify what runout.

Edit3 : axial runout still does not make sense as it could be confusing. I give up.

I think I got it now.
Edit4: radial clearance of the cam journal in the cam bearing max. .0043"
axial clearance to the center cam boss thrust surface max. .0004"

 

[James & Son]

Quote:
Originally Posted by Franko6
We use a 2-3" mike and measure from the base circle to the top of the lobe. The brand-new stock cams measure 2.430"- 2.432". If wear is below 2.424", it is worn out. .

Oilhammer: Where did this information come from? I find a wear limit of .15mm (sorry, I don't speak 'inches') in Alldata, and that is for axial play (the only dimension given). Nothing for lobes. Which I find puzzling. I also have found that even a cam that LOOKS worn (no need for a micrometer) can often still continue to work just fine for a while longer. Which is also puzzling, since the only other engines I have ever come across with flat cam problems were domestic pushrod lumps, and those go from running fine to dead cylinder in no time. The PDs don't seem to do that.

I know exactly what Frank is talking about. The distance between the end of the valve stem and base circle of the cam, leaves only about .025 to .028 in. engagement of the hydraulic follower( no adjustment as in a rocker arm set up) on a stock cam. Therefore if you use .010 in. per side to regrind the cam you have reduced the engagement to a minimum, that I see Frank suggesting is the min. limit.

If that same came is reground to provide an extra .010in of lift then the hydraulic lifters are at there full extension on the base circle.

Now I want to jump to what oil hammer said that Alldata states .15mm axial end play.
Bentley as quoted in my above post says .01mm run out. I may have made a mistake assuming they were taking about the cam axial play. In fact they may have being talking about cam bearing alignment to the cam axis.

I think Oilhammer or A5Inky should comment here or does anybody else have a source for confirming data as to what this run-out is refering to. Is it refering to axial runout of the cam bearing bore?

Edit: what am I saying, Frank is the one bringing in the bore hone type equipement. If .01mm or .0004 in. is the spec for axial bore runout then I definitely see the need for this equipement. Frank can you comment on this specification. Also what do you consider excessive axial play. Does .15mm or .006in seem right as my cam seems to only have about .001 in. at the most(very tight).

 

[A5INKY]

I am not going to try to figure out what oilhammer ment, but my hard cover bentley states the following which seems to make sense.
"Check radial clearance with plastigage, wear limit, 0.11mm(.0043 in.)"
"Max. runout:0.01mm (.0004 in.)

Anyways your the man Bob for offering.

Edit : actually, the term runout is incorrect if they are referring to axial play( axial play is in a back and forth direction of the axis). Runout usually refers to axial mis-alignment or an example is clocking each main bearing to see if their in alignment to one another.

Edit2; radial runout max. .0043"
axial runout max. .0004"
This for the cam bearings. Runout is a general term i guess and you need to verify what runout.

Edit3 : axial runout still does not make sense as it could be confusing. I give up.

I think I got it now.
Edit4: radial clearance of the cam journal in the cam bearing max. .0043"
axial clearance to the center cam boss thrust surface max. .0004"

I'm responding to this post first as set-up to a response to the next by you, as you requested via PM.

Radial runout is being referenced simply as bearing clearance. If one assumes perfect cam bearing alignment (a mistake, IMO) then this would be the same for each bearing and easily measured with Plastigage. I read this spec to be a wear-limit on used bearings.

Axial runout is the "rocking" or wobbling of the shaft relative to the head. This is a much more difficult thing to consider as there are so many factors that contribute to it. James, by your reports of your experimentation, this movement appears to be a large part of your focus. My question would be, how is it measured? Bare head with no external forces applied (valve springs, injector rockers, TB), or in-situ with all those forces present? You seem to be approaching this as an issue needing corrected in-situ. That is the approach that gets closest to solving any issue excessive axial runout may cause. Only, it is only practical on a case by case, engine by engine basis and of no use to finding improvement on a larger scale. This is the issue I have with yours and eddif's efforts, you are both working with a data from one or two heads. Even if you improve things, you only improved for that one head/cam.

For improvements to PD cam implementation to be helpful on a wider scale, axial runout issues would have to be addressed in the simple cam to bare head mating such as what Frank is hoping to achieve with align boring.

 

[A5INKY]

I know exactly what Frank is talking about. The distance between the end of the valve stem and base circle of the cam, leaves only about .025 to .028 in. engagement of the hydraulic follower( no adjustment as in a rocker arm set up) on a stock cam. Therefore if you use .010 in. per side to regrind the cam you have reduced the engagement to a minimum, that I see Frank suggesting is the min. limit.

If that same came is reground to provide an extra .010in of lift then the hydraulic lifters are at there full extension on the base circle.

I think you misunderstood Frank. He is referring to total valve lobe maximum outer measurement as a method for measuring lobe tip wear, nothing else. It is a quicker check using this dimension than taking this measurement and subtracting the base circle diameter to solve for total lift.

Regrinding cams for more lift certainly reduces base circle diameter therefore also decreasing follower pre-load. I for one think this a general improvement in the case of the VW PD.

EDIT: Oh, snap! I just realized I allowed myself to get pulled in to assist in hijacking this thread. SORRY OP!

 

[Franko6]

Sorry, while you guys are talking about it, we are installing and shipping cams sets. Talk is great, but we had to take care of the business at hand.

I know the goal is to make some proof about cams. I appreciate well-known vendors' interest, as Peter has shown. Even within this thread, there is enough dispute over what I attempted to say, that I feel there are already enough bias to go around, even before attempting to figure how to create a realistic set of dynos..

This is a place where complaints are spoken plainly from the consumer. We have the reputation backing our products. If there is a problem from our customers, we prefer to hear it personally and we fix problems. We know of very few problems where our cams are concerned. We regularly get great reports.

Now, I will say this again to attempt to avoid the confusion. Our cams, when properly installed and set, and coupled with the proper tune, nozzles, turbo and other performance improvements, will further enhance performance. We have reliable information that worthwhile increases in performance were obtained after installing the cam on a performance-improved engine. We have several BRM cams which showed additional performance above what the BEW cam will provide.

However, we do not encourage the use of the BRM cam's additional power for this engine, as we are well aware of several deficits in the cylinder head design which cannot easily be overcome. These shortcomings will reduce the life expectancy of the cylinder head, especially when the head is producing over twice it's intended power.

That being said, we also have good information that when our design is applied and used in purpose within the engine's design, that we are receiving lower EGT's, improved economy and increased life- expectancy. Those are great goals for this engine that we have purposefully designed.

We provide a cam, with chrome-plated journals for additional wear resistance, modified cam lobes for additional breathing and smoother transitions to reduce cam follower and lobe wear. We have conclusively shown that our elegant cam bearing design doubles the oil available to the cam followers, eliminating potential for the followers to overheat. After four years and over a thousand cams, we have an excellent track record and had no warranty claims for our own cam.

As for the question of cam life-expectancy, we realize that cams for the AHU, ALH and BEW have shown exceptional wear in many cases exceed 300,000 miles. We agree with those reports. However, that is not what our customer base shows us with the BRM engine.
We have seen some BRM cams fail in 70,000 mies. Many have failed around 150,000. We designed for 250,000 miles for the BRM and expect to exceed that.

Our primary interest is long service life and economy. Our secondary interest is performance, but even there, we are not interested in extreme modifications that will severely shorten the life expectancy of the head. We know these heads have a cracking problem and erode valve seats quickly.

 

[Spike_africa]

Frank, since you are more worried about stock like power and better efficiency. What kind of egt drop or mpg gain do you generally see.

 

[Franko6]

Spike, Don't get me wrong... I like to see more power. I just realize the shortcomings of the cylinder head... We can see the methods that VW uses to try to keep cracks from advancing between the injector hole and intake valve seat. They obviously know there is a problem. Getting the engine to run cooler is moving in the right direction. But it's the same we joke we say about fuel economy...

VW owners don't save money on fuel...they just go farther. If you can get lower EGT's, a performance guy will drive harder.

The best I can tell you on EGT drops are people who added the cam after making several horsepower enhancements. Few people with stock engines bother with an EGT gauge, so our experience showing EGT drops is with power-enhanced engines. There were regular comments that EGT's dropped around 200 degrees. We have had the same experience with our ALH/AHU cams. Better breathing engines will improve efficiency. It is reasonable to expect that a stock engine will see an improvement also. The Passat has an EGT probe built into the exhaust. I'd like to know how to access it through VCDS and get some stock engine data f

I think we are getting crossed up with those concerned with power over economy. It's really not an either/or picture. We have a lot of well-tuned engines with increased horsepower that, when cruising, have improved fuel economy. You can have your cake and eat it, too. You just can't usually get both at the same time, unless you're flying an SR-71.

 

[Franko6]

James and Sons, we got our PD cam alignment bar. It does exactly what we thought and works very well.

 

[bobthefarmer]

FWIW, I don't see any VE TDI cams failing, ever. I've seen a picture of one once, though. But otherwise, the only VE TDI cams I replace are from damage from a belt/moron/tooef mishap.

Anybody know what VE TDI cams are? Could you elaborate without abbreviations for a layman, Oilhammer? THanks, BOb

 

[Franko6]

I'm not OH, but if you are going to talk a VE pump, it's the engines that have rotary injection pumps, like the ALH and AHU. We do have cams with improved profiles that work with those, too.

We strongly disagree that not only CAN the VE cams can wear out, they do regularly. The cams and lifters wear in together and wear out together. As an example of that, we were working with a fellow who was stuck with a broken engine in Lancaster, CA. We mistakenly sent him an ALH cam for an AHU motor. The mechanic, Matt Phelan, installed the new lifters against the old cam. The owner of the car was headed back to Michigan and it wasn't out of his way to swing by, so we installed the new cam.

By the time he got to our place, the same NEW lifters were worn just as the OLD lifters had been. That is by far, not the only experience we have had like that. Although the older 1.5 and 1.6 engines were not prone to this (some had solid lifters), the later ALH and AHU are subject to the lifters dwelling instead of turning in the bores, as they should. When that happens, the lifter will overheat. The lifter also spins the valve to keep the seat wear concentric.

 

[TDI_Smog]

The more and more I try to fix and maintain my '06 jetta tdi (BRM) the more I feel it's one of VWs worst designed engines...

 

[stormtroopin5.0]

The more and more I try to fix and maintain my '06 jetta tdi (BRM) the more I feel it's one of VWs worst designed engines...

I wouldn't go that far. Sure it takes some special attention but everything has its good and bad attributes. I personally love my BRM even if it could have cam and rocker issues.

 

[TDI_Smog]

Maybe not. I installed Frank's bew profiled cam (I think stage 2 valve lift) kit about 2 years ago and 45k ish miles.

I looked at the cam last week and thought they were wearing but upon closer inspection I was wrong. The cam measured great. Some polishing is normal on the lobe where the lifter makes contact. Awesome product awesome. Wear rates are extremely low. Woot no more worrying!

2006 jetta tdi 1.9t brm motor. 155k miles to 200k, ~8500 miles per oil change.

 

[puntmeister]

Ok, I know I am walking into what was a contentious thread - but, here are my thoughts, and my issue:

My car: 2004 BEW, manual, 210k miles

First, issue: I get a P0101. Can't find the cause - MAF is new Bosch. EGR cleaned out & functional. From another thread, I'm told this is a known issue, caused by worn out CAM. I finally got around to checking the CAM - sure enough, some lobes worn - I'm talking lobe tips with no chamfer, sharp edges (with metal being squished out sideways). I didn't even manage to check all the lobes - but the bad ones I saw were on the ends (near TB and Tandem Pump)

I didn't remove CAM to check the lifters - but, no clicking noise. And I could see no issues with them (although view was very limited).

I see Oilhammer's point - most people don't keep a car 10+ years/200k+ miles. They are addicted to car payments - when their car is paid off, they junk it, and take on another round of payments. With this strategy, it wouldn't make sense to put money into any engine work, unless it downright prevented the car from running.

I, however, will gladly keep this Jetta going for another 100k+ miles. And, since I am in the desert Southwest, the rest of the car is in near flawless condition - no rust, etc. So, I would guess a new CAM is in order?

I read through Frank06's thread about drilling/modded bearings - there was mention of a newer mod, with modded bearings but no drilling - but I can't find the thread....(and I may have misunderstood anyway).

Is it worth going that route, even if I just use an OEM/FEBI CAM?

 

[James & Son]

Is it worth going that route, even if I just use an OEM/FEBI CAM?

If it is a Febi Belstein it does not mean it is a OE cam. A FB aftermarket cam is made to FB specs not necessarly VW specs. and could be made anywhere in the world. Those specs could be exactly the same or worse. Since VW was not exactly successful in providing a reliable cam for all situations and controling the finish quality of those cams( finish is to rough). Then most cheap after market cams will likely be a hit and miss proposition as well when it comes to surface finish and possibly hardness depending on what is accepted as minimums of quality of steel and finish.

If the surface lube film does not develop in a reasonable amount of time then you will have a sub 100,000 mile cam. Since even the OE warranty is only 12 mo. then there is very little insentive to meet an acceptable standard. Standard bearings provide lots of oil under 3000 rpm and are not the problem.

Length of warranty and return policy are what you need to look at when buying a cam. Then weigh the cost and risk.

 

[puntmeister]

Standard bearings provide lots of oil under 3000 rpm and are not the problem.

If true, this is good to know - I rarely drive over 3000 RPM.

I've read through lots of threads - no one seems to have definitively nailed down the root cause of the problems PD's have with CAMS. Any updated information, testing, theories are welcomed.

Based on logic (perhaps flawed), some reading, and a less than scholarly level of engineering, my take is the root cause is the fundamental design: 12 lobes, on a short shaft - lots of pressure, minimal time between strikes, and narrow striking surfaces.

Overcoming this flawed fundamental design seems somewhat elusive. If you try to fix the problem by just making the camshaft uber-strong, it seems to me you'd just end up with a flawless camshaft, and chewed up lifters. I am not entirely convinced the Camshafts, in and of themselves, were the problem. They could have all been made to spec, and still have had the ensuing problems.

One way or another, the high pressure/high heat would need to be alleviated. It may be wishful thinking, but it does kinda seem like Frank06's strategy of re-routing the oil to the top of the shaft (where its under less pressure), and onto the lifters, would go some way to reducing heat build-up.

Unfortunately, cost does, in my case, have to play a role. I'd love to go with a Colt-Cam, or Frank06 cam, and could easily have done so in years past - but the introduction of a wife, a kid, and one very lousy investment have resulted in, well, "a failed cam".

The Chinese fooled me once (and it cost me half a million), but it won't happen again. No Chinesium for me. I do realize the Febi (and some other name-brand aftermarket parts) may very well be made in China - but this is not the same as no-name Chinese parts. The Western brand, Chinese-made parts are done so under the supervision, specs, and quality-control of the parent Western company. The Chinese are cheats, across the board - but they are perfectly capable of making quality parts, IF they are forced to. I-phones, for example, are all made in China....

 

[oceanrunner]

I was at VW dealer the other day speaking to one of the service advisers about something unrelated and than got on the subject of the BRM cam. This SA had worked at VW for twenty years and she said that the cam problem occurred as a result of changing the oil too early. The detergents in the oil start breaking down at 2-3K miles and after that is when the oil is at it's best. But people where changing there oils at 5K causing lack of proper lubrication. She said VW really wanted oil changes done once a year but recommended a minimum of 10K. (This is what I was told...just another view of the problem).
As for the Febi Bilstein cam they are made in Turkey. I would imagine from the same factory as many other brands that are relabeled. When I removed the original VW cam from my BRM they where identical side by side as you can see below.

 

[James & Son]

Well written post Puntmeister,
I suggest you confirm the return policy and buy the cam after making sure they will accept the return of said cam if it does not meet an acceptable grind finish that will allow for an acceptable break in.

I stress this as these are not chilled cast iron that can mate easily as the previous alh. A hardened steel cam necessary due to the injection roller is considerably harder and should be around 58C for steel vs 48 to 52C( rockwell) for the cast iron. This then requires the cam to have a finer finish for proper breakin.

I think( I have locked at 3 different new cams) after market manufactures to avoid extra grind time, the cam is always ground to the roughest surface finish allowed and thus on after market cams many are of unacceptable roughness. This is why the return of the cam is important.

As far as heat build up this is due to the base circle roughness which can not breakin as the nose can. On this cam it is not the cam design flaws that you suggest that cause the heat but the fact that when the injection event takes place the cam is driven down onto the follower and if surfaces have not mated in a reasonable length, the surface film will not develop to keep the cam base circle and follower from rubbing and wearing the center of the follower. This is where having the cam parkerized will help.

It is unfortunate, the vendors of standard after market cams, I have talked to don't see the advantage of parkerizing as it allows for rougher surfaces to breakin over a longer period of time while at the same time providing a surface that will allow a lub. surface film to develop while this takes place.

Colt and Franko6 both take advantage of this simple low cost solution.

Edit: I see oceanrunner has posted at the same time. Ocean runner please tell me how you know the cam is made in Turkey. When i talked to the vendor that sells the cam you show they said Febi has sources all over the world. I believe Brazil makes cams, i think there is a major manufacture in Italy as well as AMC in Spain. Just interested to know your source.

 

[bl00tdi]

Well we know that most of the time it's the exhaust lifters/lobes that wear. I pulled my bearings at ~95k and none of the oiling slots were covered up by the cam so the running position was still good. But..........wear on the #1 exhaust lobe nevertheless. All the other 7 lobes were picture perfect. This, to me, proves that oiling is sufficient in most cases even with unmodified bearings. Something about the exhaust lifters on either end of the engine causes issues though. In other words, it seems that covered oil slots exacerbate wear that's already occurring and the issue compounds until catastrophic failure. That's what my anecdote would indicate, anyway.

 

[puntmeister]

If I am understanding correctly, it sounds like the Cam lobes are being pushed against the followers due to downward pressure of the Camshaft when the injector lobe pushes up against the rocker.

ie - the lobes are rubbing the followers when & where they really shouldn't be, along the base of the lobe.

Would it be correct, or likely, to suggest this only starts happening after the lower bearings have worn to a certain degree?

ie - when new, the lower bearings are thick enough to prevent the camshaft being pushed down far enough to close the gap between the lobe & follower? As the bearings wear down, the gap between the lobes and the followers closes.

If this were the case, perhaps a preventative solution would be to periodically change the lower bearings - say, every 25,000 miles. A bit of a pain, but less painful than outright changing a camshaft.

 

[James & Son]

If you go on my photos album you can see I have spent a lot of time testing different solutions to my follower galling. All the solutions may help longevity but didnot help the galling that happened when the black coating began to wear thru at 35000 miles. I replaced all the followers as the cam nose was still breaking in and the base circle was still very rough. I have 80,000 miles on the cam now and have replaced all the exhaust followers once more and #1 & #2 cylinder exh. three times. The base circle is just wearing in now and I feel shortly the very hard cam will have surfaces that prevent rubbing. I also added a lubricity additive to help the oil film development at lower rpms this last oil change.

This is why if the cam had been parkerized the softer parkerize will fill in the roughness and helps form a surface that supports an oil film while the rough asperities slowly smooth as this surface slowly wears away.

Then to answer your question Puntmeister.

As long as the cam surface can support an oil film then any other modifications may not be necessary. I just bought GoFasters car which has 436000 kilometers (272000 miles) and has the original cam in it. The valve cover has only been off twice in its lifetime and the last one was me not more than 6 months ago and the cam had very little contact wear only #4 cylinder lobes had a slight contact haze on the base circle. The only other contact was the very nose of the cam which I would attribute mostly to initial break in. This car ran its whole life mostly on the highway at over 2000 rpm.

Now the base circle finish of the cam showed the original grinding finish and it was a fine homongenous grind finish.

Now why did this cam not rub on the base circle. The cam in my other car does rub on the base circle and only at 80,000 miles is it becoming smooth enough I believe it will soon start to support an oil film and It will actually start to live a normal life. In other words it was so rough it took 80,000 miles to breakin.

This latter cam is a cam that would not normally make 100,000 miles due to distroying or prematurely wearing the follower due to roughness.

I think you will get acceptable life if your cam grind is done to a standard that allows mating( oil film development) in 7500 to 10,000 miles. This includes the base circle. I think parkerizing is beneficial here as well.

 

[Spike_africa]

From what I have read and see. I will get a mild hardened one with OEM followers.

 

[bl00tdi]

If I am understanding correctly, it sounds like the Cam lobes are being pushed against the followers due to downward pressure of the Camshaft when the injector lobe pushes up against the rocker.

ie - the lobes are rubbing the followers when & where they really shouldn't be, along the base of the lobe.

Would it be correct, or likely, to suggest this only starts happening after the lower bearings have worn to a certain degree?

ie - when new, the lower bearings are thick enough to prevent the camshaft being pushed down far enough to close the gap between the lobe & follower? As the bearings wear down, the gap between the lobes and the followers closes.

That's an interesting thought but if that were the case, failure would be distributed evenly between intake and exhaust lobes but as we've seen, it's not. Something specific to the exhaust lifters is happening here. But we agree that it seems that there's not enough valve clearance.

If this were the case, perhaps a preventative solution would be to periodically change the lower bearings - say, every 25,000 miles. A bit of a pain, but less painful than outright changing a camshaft.

Please refer to my anecdote. 7 out of 8 lobes were perfect at 95k with no copper showing on the lower shells and oil slots were uncovered. There was no evidence to suggest that the bearings themselves had been contributing to any wear but I changed them anyway as to not waste the opportunity.