Let me say right up front, that this posting is in no way slamming ISKY' EZ Roll bushing lifters. On the contrary, this info will show how well they hold up, considering that ANY solid roller lifter is a maintenance item that will need to be replaced regularly.

Before getting into the failure data, here's a little background info on solid roller lifters. Keeping an eye out for any lash changes, as well as regular removal and inspection is basically the standard recommendation for running solid roller lifters. But, the problem is, that ultimately may not save your engine. Here's why, the root cause of their failure is metal surface fatigue failure from all the jackhammer pounding they take from not following the carefully designed cam lobe ramps, when they bounce around within the lash slop. They are not forced to ride nicely on the lobes like hydraulic lifters are. And since solid roller lifters don't always directly ride on a lobe, the opening/closing lobe ramp design goes right out the window, and the roller gets smacked by the lobe, or smacks down on the lobe, depending on if it is rising of falling. The larger the lash, the worse this is. Eventually, this repeated over and over jackhammer pounding takes it toll, and metal surface fatigue failure bites you. You can't predict it, you can only see it once it begins. And to add insult to injury, you could inspect your lifters one day when they look and feel just fine, and the next day you can suffer metal fatigue failure and things go south.

Bushing type solid roller lifters are way more durable than the needle type, because the needles only make a very tiny line contact (thus extremely high psi loading values are seen), so they are severely overloaded in this application. Plus, in .842 lifters, only the bottom 3 needles take all the load. They are just a failure waiting to happen.

But, the bushing type lifters provide a far larger surface contact (thus they see far lower psi loading values). ISKY says their EZ Roll bushing type solid roller lifters provide a 350% higher load rating than comparable needle type solid roller lifters. However, even the bushing lifters are not immune to failure. The bushing type lifters are subject to roller OD metal fatigue failure, but the needle lifters are subject to "BOTH" needle and roller OD metal fatigue failure.

And this brings us to the subject of this posting. A fellow Forum member contacted me about a solid roller lifter that had failed in his engine (he asked that his name be left out, so that he could be left out of any controversy that may come up). He knew I had performed root cause failure analysis on a few sets of failed needle type solid roller lifters, a few years back. So, he sent me his bad bushing type solid roller lifter for failure analysis.

He runs a 467ci Mark IV BBC in his street Hotrod, that see's a lot of "spirited driving". The rev limiter is set to 6800 rpm, though the most common normal rpm seen is in the 3000 to 3500 range. his cam specs are 243*/249* duration at .050 tappet lift, 112 LSA, and .668 lift. Lash is .008 cold, .014 hot with aluminum heads. Spring pressures are 210 lbs on the seat, and 525 lbs open. His solid roller lifters are .842 diameter ISKY EZ Roll bushing type.

He doesn't let it idle. As soon as it fires, he starts driving although not too heavy on the gas until it warms up. He also pre-heats it on chilly mornings with an oil pan heater and a block heater. He also uses an Amsoil pre-luber. And he has been using Valvoline 10W-30 with a can of Moly Slip E added with each oil change, at approximately 1500-2000 miles. Valve lash gets checked a couple of times a summer, as does spring pressure. He put 25,000 miles on these lifters when he had this lifter failure that took out the associated lobe, and the debris from all that also opened up the lifter bore. The whole thing required an engine rebuild. Not fun, to say the least.

Here are the results of my analysis:

The remaining good lifter of the pair, for comparison:

Roller OD looked fine, and OD = .7500

Bushing ID looked fine, and ID = .3200

Axle looked fine, and OD = .3176 to .3179, with average = .31775

Bushing/axle clearance = .0021 to .0024, with average = .00225

***

Failed lifter:

Roller OD was completely destroyed from a text book case of metal surface fatigue failure, which is exhibited by flaking and pitting called spalling. The OD = .5870 to .6178, with average = .6024, so about .150 worth of diameter had flaked and crumbled off, thus destroying the associated lobe in the process.

Bushing ID generally looked alright, but there were signs of debris having worked through the clearance, causing wear and some scratches. The ID = .3223 to .3230, with average = .32265.

Axle looked fine, and OD = .3173 to .3182, with average = .31775

Bushing/axle clearance = .0041 to .0057, with average = .0049


BOTTOM LINE:

He did quite well with these ISKY EZ Roll lifters in terms of how many miles they lasted, even though it ended up causing a rebuild. Solid roller lifters in general, are a fairly poor design, because, as mentioned above, they are subject to the non-stop jackhammer pounding as the lifters bounce around within their lash slop. They get pounded because they cannot faithfully follow the lobe's opening and closing ramps. Eventually, the pounding takes its toll, and the unavoidable metal surface fatigue failure results.

And for the record, NOTHING you do with oil or oil additives will make any difference here, because oil has absolutely nothing to do with this type of failure. Idling also has NO affect on this failure either. Idling generates the lowest loading and pounding these lifters will ever see, because the valve train acceleration is at its lowest value during idling.

This problem is simply a fact of the Physics involved, and cannot be avoided with this design. So, there is no absolutely safe plan when it comes to running solid roller lifters. They can fail at seemingly any amount of time or mileage. All you can do is replace solid roller lifters with fresh ones at an interval before metal surface fatigue failure results, which may take out your engine as well. What that interval is, is the million dollar question, for which there is no clear absolute answer. Everyone has to make their own judgment call on that. Words to live by - you can never replace solid roller lifters too often...

540 RAT

Mechanical Engineer

U.S. Patent Holder

Member SAE (Society of Automotive Engineers)

Member ASME (American Society of Mechanical Engineers)

To see my entire 130+ motor oil “Wear Protection Ranking List” Blog (with over 60,000 “views” worldwide), along with additional motor oil tech FACTS, which are "proven" by Physics and Chemistry, and exactly matches real world track experience, go to this link:
http://540ratblog.wordpress.com/

 

Now that is an interesting and Eye opening Post. I have been running Roller Cams for the last 40 Years, and some of them were solids. Altho I never had any failures , Mine were smallblocks and I always used a "Rev Kit".

In Your opinion do You think a rev kit with the extra Springs to keep the lifters in contact with the cam lobes would of helped to alleviate this problem ? Stan.

 

Same here. That's very reassuring.

How many miles have you gotten with them ?

 

The first one back in 1974, I used an ancient Isky RR7000 with Crane lifters and Rev Kit . I beat that Motor Unmercifully for about 30k miles until a con rod ventilated the block. That was the end of the numbers matching motor of My 70 Corvette . I had a few others but they were changed or sold after 5-10k miles.

 

25k out of a solid roller lifter is pretty good id think
How many failures do we see in the 3-5k range lots in comparison
Was he still running the same springs?

There is a risk with solids but its like a bad gilrfriend with a smooth voice, hard to say no to

Wonder if using a larger lifter bore, bushed lifter wheel with a bigger wheel would solve this to an extent

 

I still do not understand why the solid rollers go haywalk and the factory (hydraulic) rollers do not. Only difference I see is spring pressures and lash hammering.

3-5 k is really short imo.

 

The hammering makes sense to me
that and higher spring pressures than we used to see with flat tappets
With the std lifter bore theres a lot of pressure on maybe a few needle bearings thats gotta be hard on them esp if they sit a lot (like mine does) maybe not. 540rat has done his research though probably the best one to listen to. He takes a lot of flack but still contributes a ton, betting he digs in his own pocket a lot to find his info too...kind of validates things in my mind some.

 

I also find this post very interesting.

I'm running Comp solid roller lifters and would need to check with my builder on if we used needle bearings or bushings.

We made some compromises for the sake of durability...reduced the spring pressure somewhat to 160#, run a fairly tight lash (0.14/0.16 cold on aluminum heads) and run a rev kit to limit the punishment the lifters need to endure.

I have my rev limiter set to 6,000 right now and while the engine IS pulling like a freight train to that point, I don't know that I'm going to goose it up much more. I don't have much interest in screwing something up.

I have about 1,500 miles on the engine so far. No troubles and no lash changes in two checks. I will check it again this winter.

I am building a rolling chassis outside of my car right now. When I pull the engine out, I will probably take that opportunity to do a "checkup" on my engine. May not pull the cam, but will pull lifters, pushrods, rockers, main bearings, and several other items to check for abnormal wear.

Always good to understand this type of stuff a little better.

 

Well, it's not a text book example of a scientific investigation. A lot more info schould have been published as to how the clearance was measured and so on. Not that I think that it might not be true but I usually like to see some more info before I make a judgement.

Anyway, I have always had my doubts about a bushing in that place, for the reason that the lifter do not have the kind of pressure fed lubrication that a bearing for instance has. Therefor I do not think a lot of hydrodynamic wedge is forming.

I put my bet on hammering being the main culprit. In that respect it's usually better to run too much pressure than too little. As I've read in D. Vizards book about camshafts, one trip into valve float or valve bounce will brinell the lifter on the lobe.

I'm a hard believer in a revkit for this reason as there is no slack between the lifter and the lobe.

I also believe in using a shaft rocker system, as there don't have the rocker moving up and down on the stud + the use of a roller block with the +.300" lifter bosses that add stability to the lifter + correct lifter clearances.

 

Couple of things, was he using the same springs for 25,000 miles? if so at >500 lbs open pressure then that is the root cause, nothing lasts forever so that means the lifter itself is not the problem, it is the pounding and jumping lobes etc. He is lucky to get that many miles. Sooner or later any solid roller lifter is going to fail.

My own experience is don't expect much more than 20,000 miles. If (whatever the brand lifter) they are still rolling at 20,000 miles I would swap the lifters and springs out anyway to be on the safe side.

My rule for a street roller is <200lbs on the seat and <500lbs open. For needle bearing rollers I check the lash quite often and note any that need adjustment. Then I check the lifter and all valvetrain components twice a year.

I have caught a lifter before failure doing a test for brinelling of the needle bearings. Just one of the 16 was on it's way out and this was with over 20,000 miles.

There is no need to be worried about solid rollers as long as you stay on top of them. They are not a part you put in and forgeddaboutit.

They are like tires, there is nothing wrong with brand new set of tires so they are not the cause of tread wearing down to the point where they have to be replaced. It is constant friction with road surfaces that causes the tread to wear

 

x2
personally I dont worry about it if one goes save up fix it and drive it again thats what they are for

 

The title of this thread as it is here and on many other forums should be:

Isky Bushing Lifter Exceeds Intended Usage.

 

Many racers replace them after 200 runs, some will run them as long as 800, but they know it's pushing it. Even 800 runs is only 200 miles, I'd say they did pretty good to make it 25,000 street miles!