BBC solid roller lifter failures - a root cause analysis

[bigjoe1]

I have had several guys call me and say thay the Isky trick lifters without the needle bearings also fell apart, so dont hold your breath, sorry

JOE SHERMAN RACING

[TheEngineWorks.com]

Ok, I have some take on this roller lifter failure.

We just ran Hot Rod Magazine's Drag Week, the engine we have in the car has a set of Predator heads, of which, they are the ONLY set in the World on a street driven car. We had an issue from day one, we realized that we were having a coolant flow issue, due to lack of flow through the heads, we lived with it for 5 days on the road and over a 1000 miles of driving. The first day on the road we had a hell of a time with heat going up through some small mountains to get to our second track, I wear ear plugs as I don't want to listen to all that clattering, my co-pilot poked me and said listen to that, i pulled my earplugs and KNEW I was hearing a TON of valve clatter due to the lash going through the roof. This engine has a KB aluminum block and a pushrod almost a foot long, so you could only imagine what the valve lash might of been..

Anyhow, we made it to the track w/ only minutes to spare and laid down the fastest pass of the day w/ only one pass, we hit the road to the second track with our overheating engine, made it to the next track, only thing is we killed a roller lifter, pulled the intake and changed it, that was the first of FIVE intake pulls to change out killed lifters!!!


This combo has a little over .800 lift and over 300 dur. @ .050, we have 335# seat and 790# open, I feel we MUST drop the pressures to try and save the lifter on the street, may have to sacrifice some valvetrain control on the track, though. I also feel the overheating and lash growing to crazy numbers beat the lifters out of it, also the oil temp was probably way up there as well, although I have no oil temp gauge, but based on the 30PSI drop in oil pressure at cruising speeds I would assume it was very hot. This HAS aluminum rods. I think in hindsight, running the lash at zero cold woulda' helped things out, which we did after the fact. We run gapless rings and even w/ two 1200's on a tunnel ram and 589ci it burns as clean as could be, also got about 10MPH on the road, w/ a/f at no less then 12.5.. I don't think fuel in the oil was really an issue. We run 15/40 Rotella

We do NOT have lifter oiling in this block, but may add it in the future, so pressure fed lifters are not really an option. We have ran the standard Comp rollers for 2 1/2 years w/o a single failure, but we have also stepped up the cam a good bit, so we may of opened a can of worms now. I think for now we will go back to the Comps, but before Drag Week next year we may look at other alternatives.

I feel running the lash tight for street use will help keep from POUNDING the bearings out of the lifter. My theory is that some of the hardest loading that the roller is gonna get is when the lifter hits the ramp and takes the lash out, what do ya think?? With the aluminum block we run, and a 440-1 head, which had a pushrod about 4" shorter I think we gained about .014 lash from hot to cold, so setting the lash at zero cold would probably work good with the new heads, although when it goes back together I will check the lash from cold to hot.

Anyhow, i am rambling, hope something was gotten outta all that mess. lol




P.S. In the end, we pretty much killed everything in the engine, BUT won our class!! Hey, its all for a jacket!

[MadBill]

Great performance in the face of such adversity!

There was a lengthy thread on the durability of solid rollers on the street some months ago, and a persistent theme (in addition to low idle RPM) was the negative effects of large lash causing high impact loads and harsh accels. Among other fixes, rev kits and some kind of trick in-lifter preload springs were mooted...

[Strange Magic]

This is not too complicated. The oem lifters seem to run 100,000 plus miles with no failure.

What do you think would happen if you used a G78 tire on a 14x5 inch rim and mounted it to a 11,000 pound box truck?

I truely do not think conventional mechanical roller lifters are intended for the following:

1. Low rpms and lack of pressure and oil splash.
2. Excessive mileage use with violent ramps and high spring pressures.
3. High oil temps over extended periods of time.

If your looking for severe duty over extended periods of time, than you might want to research a better quality lifter and design like a .937 keyway Jesel.

P.S. It would not surprise me one bit, if a conventional mechanical roller lifter doubled its life, when the ramp severity and lift was changed.

[CamKing]

Like everyone else who is interested in BBC solid roller lifter failures, I wondered just what is really causing all these failures……..

Were you running oil restrictors in the block?

I've got a lot of customers running both the Crower and Morel roller lifters with the pressure fed oiling on the street.
We haven't seen any issues.

I normally keep the lobe lift around .410", and run about 220-240# on the seat.

[Lasher...]

Nearly 30 years ago I was involved with basically an slightly modified LS-6 in a 57
Chevy street car project.He used an old school Isky roller .640 lift , 304* @ .020 , 264* @ .050 , 108 LSA lashed @ .028 hot.

Engine was street driven often 2 or more hours at a time with an idle speed of approx 1200 RPM.Standard Isky Roller tappets (no special oiling ).... Ran the car @ Fremont and ran mid 10's with slicks...... Sold the 57 and put this same engine in a boat with a Lenco and went river racing on weekends....
Ran it for 6 years in the boat..... every winter he took at look at things and had to shim the springs once...... Never hurt a lifter...never broke a spring ... during it's 7 th year the engine died when the oil pump pickup broke.

Another example is with a BBC Chevelle during about the same time.He ran a Crane .663/.638 lift , 298* / 308* @ .020 , 260*/270* @ .050 , 110 LSA lashed @ .028/.030...... Ran the standard Crane lifters ... also idled around 1200 RPM. Drove this for many years and over 30,000 miles.This cam actually went into 3 different BBC combos..... always ran deep into the 10's and was very well behaved on the street........ So a few years ago he decided to retire this cam and went with a more aggressive low .700 lift Crane rollers that Crane flat out told him not to run on the street.

He ran it anyway and inside 6 months killed 4 lifters..... He took the old school Crane out of retirement and back in it went and it is still in there now.

Both the Isky and the Crane examples above were " Old School" easy on parts lobes that were designed in the 70's...... Sure the newer stuff makes more power.... but for running an 11 -1 BBC into the mid 10's in 3500 pound cars you dont really need killer lobes.

Maybe it was luck.... maybe it was the long ramps..... maybe it was perfectly bored lifter bores..... I dont know but often times the old school stuff will run a number and live.

[tjs44]

not a chevy deal but still 842s in some pontiac engines.I have been running solid roller cams on the street for at least 8 years now.Only had one problem and it was with isky std rollers at std type lash adj.ALL my other engines have 400 lobe lift tight lash(6 thou)with 200 on the seat and 600 open.Cams are from 236-242 to 252-260.Never have had a problem with the tight lash with Comp,std lifters,Comp hi pos,Crower hi pos.Also keep my idle at 1100.FWIW,Tom

[stealth]

they all suffered from the exact same mode of failure, in the form of extensive surface pitting on the axles and needles, which is also called spalling ………..

Thanks 540,

did you check to see if there were any tiny flat spots on the rollers. I always wondered if it wasn't the roller getting "flat spotted" from lash and valve float etc, once they had these spots they would pound away a the axle..

Just wondering

[stix818]

This is not too complicated. The oem lifters seem to run 100,000 plus miles with no failure.

What do you think would happen if you used a G78 tire on a 14x5 inch rim and mounted it to a 11,000 pound box truck?

I truely do not think conventional mechanical roller lifters are intended for the following:

1. Low rpms and lack of pressure and oil splash.
2. Excessive mileage use with violent ramps and high spring pressures.
3. High oil temps over extended periods of time.

If your looking for severe duty over extended periods of time, than you might want to research a better quality lifter and design like a .937 keyway Jesel.

P.S. It would not surprise me one bit, if a conventional mechanical roller lifter doubled its life, when the ramp severity and lift was changed.

Exactly what I did. Hoping this will eliminate future problems. I have a feeling on mine that I lost the lifter bore due to the large amount of flex that the pushrod created. Pushrod was 10.900" 3/8 .080" wall and my belief is it had a HUGE amount of flex. Upgraded pushrods and lifters!!

[CamKing]

Re: "when the lifter hits the ramp and takes the lash out"

I agree, and part of the problem is that a roller does something that doesn't exist with flat tappets: the tappet cannot "escape" by transferring the ramp vector directly into lift since the contact is tangential to the lobe surface at perhaps 7 or 8 o'clock position (rotation: CW), and the more aggressive the lobe the larger the side-thrust component of the vector (of course, 6 o'clock is a flat tappet, and 9 o'clock is death).

Are you saying that when a flat tappet cam is riding out close to the edge of the lifter, there's no side thrust?

BTW, A flat tappet cam is the same as a roller cam with a 56" radius roller.

[TheEngineWorks.com]

Re: "30PSI drop in oil pressure at cruising speeds"

If your temperature drops your pressure at cruising speed something is very wrong with your oil system. Oil temp at cruise is a function of load (the same as everywhere else), and regardless of gearing, compression etc. you're only pulling perhaps 50 hp out of the motor.
Do you have a temp gauge, and where?
Is the pan shrouded?
Any external lines?

Problem being we we had a coolant flow issue with the cylinder heads, we have the engine apart right now and see some easy fixes that can be done w/o utilizing any external lines, so that problem should be solved next time around.. The oil temp was going through the roof due to all the uphill running in the heat of the day in Alabama trying to get to the next track. We run aluminum rods and block which probably grew the bearing clearances to ridiculous sizes, and there goes the oil pressure. We run a Milodon dual line p/u wet sump setup w/o an oil cooler. I believe I am gonna put an oil cooler on it before it goes on Drag Week next year.

I don't know what the oil temp was, but I bet it was hot, we had water temps around 230/240 for a good part of the time while making the uphill runs.

[PackardV8]

We're a bit off-topic here, but I agree,

and regardless of gearing, compression etc. you're only pulling perhaps 50 hp out of the motor.

An oil temp gauge will verify the above. Once water temp stabilizes, it usually stays within a fixed range above ambient, say 100-150 above. Oil temp is strictly dependent upon load. Even when water temp gets to 200 at idle, the oil is still cold. Conversely, if the load is greater than the oil cooling system can disperse, oil temp will continue to rise. I grew up there and know the Alabama highways well. The hills only seemed high because you were worried about the engine. If you were seeing 230 water temp at highway cruise, your oil was probably less than that. BTW, the larger clearances and aluminum block and rods actually lower oil temp by increasing flow. Pressure is the measure of how much oil is not getting through the bearings. Bottom line, fix your water circulation problem and your oil is probably fine.

thnx, jack vines

[Wolfplace]

And rather than rehashing this I will just refer everyone back to the last thread about the exact same part & point out that Mr Rat has no actual experience with these lifters in a running engine as of yet,,, just opinions on the design which he is of course entitled to
But he had started out with nothing but negative opinions based on nothing but one persons experience & gone on from there

Now to be fair, as I have stated everyone is entitled to his or her opinion & Mr Rat may have some valid concerns & I really do enjoy reading his take on things, can't help but think about what is stated
But my opinion on this particular subject is this design has seemed to fare pretty well in the real world so I will continue to have faith in the product.

Read this thread from top to bottom, it is long but has a bit of factual real life results regarding these lifters & this is much more important to me than any one persons opinions of a design they have not tested & assume to be inferior.
http://www.speedtalk.com/forum/viewtopi ... rs&start=0

You might want to add this one to your reading too
I already reluctantly voiced my opinion there so I won't bother to repeat it here,,,
http://www.chevelles.com/forums/showthr ... 316&page=9

[540 RAT]

CamKing, UDHarold,

You guys are professional cam designers, so here's something perhaps you can shed some detailed light on. While most of us run the recommended lash, some guys run or at least ask/think about running unusually tight lash in an effort to minimize valve train hammering. However, I expect that you guys will say, "a properly designed lobe, run with the recommended lash, will not be hammering the valve train". If you do in fact say that, can you explain in some detail why running a tighter lash would be a bad thing, and what the downsides of doing that would be. For a real world example, let’s say we have a BBC Comp Cams solid roller cam, with their fairly aggressive Extreme Energy lobes, with specs of 266*/272* at .050, .678/.688 lift, that calls for .016 hot lash. So, let's say we want to run it at half that, or .008 hot lash, which works out to .002 cold lash. We have clearance, so nothing is tight. What happens if you do that, from a cam designer stand point? Thanks for you input.

[540 RAT]

And rather than rehashing this I will just refer everyone back to the last thread about the exact same part & point out that Mr Rat has no actual experience with these lifters in a running engine as of yet,,, just opinions on the design which he is of course entitled to
But he had started out with nothing but negative opinions based on nothing but one persons experience & gone on from there

Now to be fair, as I have stated everyone is entitled to his or her opinion & Mr Rat may have some valid concerns & I really do enjoy reading his take on things, can't help but think about what is stated
But my opinion on this particular subject is this design has seemed to fare pretty well in the real world so I will continue to have faith in the product.

Read this thread from top to bottom, it is long but has a bit of factual real life results regarding these lifters & this is much more important to me than any one persons opinions of a design they have not tested & assume to be inferior.
http://www.speedtalk.com/forum/viewtopi ... rs&start=0

You might want to add this one to your reading too
I already reluctantly voiced my opinion there so I won't bother to repeat it here,,,
http://www.chevelles.com/forums/showthr ... 316&page=9

Wolf, Wolf, Wolf,

You just can't help yourself can you? The reason I started out with a bad opinion of Isky lifters, is because when I first got my hands on a set of Redzones, I saw how poorly they were designed. I really expected better from one of the well established names in Hotrodding/Racing. It really doesn't take a genious to see this stuff, you just have to look closely, that's all.

Yes, it is true that I have not yet fired my new 540. But, that has nothing to do with the poor design of some aspects of Isky's lifters. I would have thought with all your years of experience, that you of all people would have noticed these short comings as well. I never said they don't work, in fact I specifically said that they seem to be doing well in actual usage. That's why I bought them myself, even though I do not like some of the design aspects.

I challenge you to prove how I'm wrong about the design problems I listed. And just saying they work, is not good enough. Many things in life work, though they are poorly designed. I'm only saying they could be much better in terms of design and manufacturing. And I guess it is just my bad luck that I'm the only one in the country to have those lifters stick in their bores. I swear on my mother's life, that that is the honest to God truth. I did not make anything up. Everything I stated is factual. I have absolutely no reason to make this stuff up, I only call 'em as I see 'em, for better or worse. I have praised Crower for their excellent design and manufacturing (but they don't offer bushing-type lifters), and I'd do the same for Isky if it was warranted. And I have nothing against Isky in general either, only what I've come across with their lifters. For all the money my engine and those lifters cost me, I certainly hope they last forever, nothing would make me happier.