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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Finally (finally) got around to working on the car again. It's been shelved for the past 3 years more or less.
I knew there was an issue with the engine although I have to say it ran rather well. Despite the damage that I'd find.
Intake removed and voila! (Excuse the mess. Prior cleaning was not a necessity as it's all coming out).
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A few pictures to show similar wear on the damaged set and a working set.
All lifters have the same markings.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The rivet holes on the failed lifters don't appeared to be damaged. The black oxide is still intact. With the body of the lifter being tool steel and I imagine the rivet is not, it's understandable what the weak link is in that assembly.
---------------------------------------------------------------------------------------------------------------------------------------------- The rivet looks to have the peened over section snapped off.
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There doesn't appear to be any indicator that the other rivets are at the point of failing although the joint does appear a little sloppy. Without a fresh set to compare too, I can't say how much movement is within spec.
While it's been a long time since I built engines with aftermarket roller cams/lifters (Crane and then Isky), I never saw any of them fail like that under drag-racing conditions.
That engine is no doubt full of metal particles, but it sure could have been much worse---and not rebuildable.
Exactly the conversation I was having with a racing friend. It was suggested that the broken parts were responsible for the engine problems I was having and after discovering that, maybe the shortblock could be pressed back into service without disassembly. I won't disagree with the broken parts bit but with the amount of metal that's obviously missing from the damaged roller, I'd say that is not an option.
Besides that, I'm pretty sure that measuring the bores will show that they're worn out. Compression testing has showed a steady decline from the original cranking pressure of about 185 to the current pressure of 165. And at least one cylinder another 10% below that.
Toast.
That is an odd failure. Wonder if the lifter roller failed first and caught the cam lobe putting pressure on the link bar? I cant see why there would be a lot of twisting force in a roller lifter application.
when i lost a lifter in my bbc it ate up the cam lobe and metal was in the engine. I had to replace bearings and flush block, however i did not tear it down completely... i took crank out while leaving rods in, and flushed oil thru engine oil pump. It seemed to get a lot out. Probably not the best way to do it but its been running good since then.
The path to failure will probably never be determined. It looks to me that the rivet failed. Simple as that. All rollers, including the mangled set, still spin freely. Not thinking that one of them seized based on that.
But as I said, it's only speculation. If it weren't for the question of fatigue, I'd buy one replacement pair and put the others back into service. But I'm not so sure that's a good idea.
Thats what is strange i would not think the rivot and bar is under much stress
edit: well i guess if the lifter bore is canted some it would put forces on the rivot and bar. If u tear down i would buy new set of lifters and have shop recheck lifter bore alignment/clearances etc
Including the fatigue angle I'll say that the occasional 7000 RPM touch off the limiter might have been excessive.
Valve train geometry is spot on. Absolutely spot on. Springs are COMPs bigger beehive 26918. Light tool steel retainers.
7000 might have ok when everything was fresh but the miles have been piling up. The rocker trunnions were showing their age too. Could well be all the hot rod goodness was used up and something had to give.
As far as the stresses on the link bar go, probably not a lot of leverage being applied but the link bar might have acted like a saw on the rivet. Give it enough cycles and its caused enough damage to weaken the part. Maybe some crap got stuck in there.
It might be as I take the engine apart there will be other clues. I'm interested to know the condition of the lost link.
You are going to have to replace the Camshaft and that Lifter-Pair at the very minimum.
Good luck!
The cam for sure. This piece of cam lobe I pulled off the drain plug is what started all of this. Engine has been sidelined (more or less) ever since. That's was 2018.
A demonstration comparing the fragment to a cam off the shelf.
That cam is another old timer. It's been in the family more than 20 years and has seen its share of hard miles.
I'm not entirely sure I'd put the remaining lifters back into service. As it is, at a minimum, this block will get a complete remachining. I'm hoping it has room to go .040" over but my preference is a new 383 short block. So with any of the above, it would make sense to renew the top end too. The heads are fresh. Very few angry miles on them and I hope that a teardown will show they're good to go.
Lots of parts needed.
Time to get some parts. Get a billet cam core if you are gonna stick with aggressive lobes imo. Get some good lifters. I know its money but much more durable
Time to get some parts. Get a billet cam core if you are gonna stick with aggressive lobes imo. Get some good lifters. I know its money but much more durable
Agreed.
As for an aggressive lobe, that'll be the topic of another thread. At one time I tried to get Mike Jones involved on where to draw the line between maximum output and longevity. He referred me to Harvey Crane's old paper on lobe intensity (which I had read years ago). But nothing definitive came out of that.
Something along the lines of comparing his EHR lobe to his HR. For a given seat to seat duration (say 284) there's 14 degrees to be had at .050" (238 vs 224, .360 lobe lift vs .308) . But at what cost? A pile of broken valve train parts after 20 miles into the Silver State Challenge? Sims show the faster cam makes more power everywhere but is that gain worth the pain?
Stay tuned.
I personally find that Hydraulic-Roller Camshafts do not usually have an aggressive enough Lobe shape to warrant a Billet-Steel Core.
If you were going to a Solid-Roller Camshaft, than that is entirely different.
There is no harm going to the Steel Camshaft, just get the appropriate Lifters...
and say goodbye to some Money.
Want to make sure I'm not missing anything. The "missing link" was certainly easy enough to find.
But if I look at these lifters, we'll call them 1-4 L to R, 1, 2, and 3 all appear to have nice "flat", "Square shouldered" rollers (3 looks a little funny because it's being viewed slightly from the side). But does number 4 appear to have a rounded appearance?
Originally Posted by skinny z
7000 might have ok when everything was fresh but the miles have been piling up. The rocker trunnions were showing their age too.
What sort of wear were you seeing there?
Originally Posted by skinny z
Could well be all the hot rod goodness was used up...
Want to make sure I'm not missing anything. The "missing link" was certainly easy enough to find.
But if I look at these lifters, we'll call them 1-4 L to R, 1, 2, and 3 all appear to have nice "flat", "Square shouldered" rollers (3 looks a little funny because it's being viewed slightly from the side). But does number 4 appear to have a rounded appearance?
What sort of wear were you seeing there?
The two lifters on the right where free to rotate in their respective bores once the link bar was gone. From the look of the roller on the far right, I think it's fair to say the lifter was free to spin (I'm talking about the lifter itself rotating like a flat tappet would) the result being that nice smooth radius cut into the roller. It's very much shaped like a ball bearing now. Same thing but to a lesser degree with it's mate. The other seven sets look like new. Or nearly so.
As for the rocker trunnions, the bearings were getting a little sloppy. They should be rebuildable.
The "missing link" is in the oil pan I would think. Which I'll get to eventually.
Link bars keep the lifter square to the cam. Without it, the lifter will rotate in the bore. Once it rotates, the roller no longer rolls over the lobe. It just becomes a round piece of steel sliding against the cam lobe. Over time, the roller and lobe wear out. When I find them in diesel engines, it's usually because the worn out lobe/roller increased the lash and a valve bridge falls off a pair of valves. Since the valves don't open, you get popping sounds, usually out the air cleaner.
When stripping down an engine for cleaning, one thing that's usually missed is cam bearings. A lot of metal can get trapped behind the bearings in the oil galleries. Before flushing the engine to clean out all the metal, remove the cam bearings.
As for squareness of the lifter bores, non roller cam blocks are never 100% machined properly. They're close enough for a production engine to work. Add in a set of link bar lifters and like mentioned above, there may be some binding due to a slight misalignment. If using a production block, it costs money but having the lifter bore alignment checked and bushed may be an option.
An aftermarket block should not have that problem as tolerances are a lot more exact. My Dart Big M block isn't cheap but it surpasses the limitations of any production block. In one of the engines that I blew up, I cracked the webbing under one of the crank mains. Threw the block in the scrap metal and bought another.
What's kind of funny about this is that the lifter was working as it should. Even fully sideways it worked as a flat tappet would. Not for long mind you and I'm glad I found it when I did. I had a valve drop once and it wiped out everything save for one head and the intake manifold.
This particular engine was a copy of another that was very successful and long lived. Matter of fact, this shortblock and current cam were part of that package. I refreshed the short, added my own cam (274) at first and with my RHS heads on it, I laid down my personal bests at the track. Worked great. Then more work on the heads and I figured, what the hell, I'll step up the cam and went with the original 288. Fast forward to the mess I have today.
As I mentioned, a little bit of high mileage, some overenthusiasm, and it's a perfect storm for something to let go. Interestingly enough, all of the parts in and of themselves, were more than up to it. Who would hesitate to go 6500-7000 RPM with that list? We'd been doing it for two decades already. Sometimes ***** just blows up I guess.
As for the crap that's undoubtedly filled the engine, I've learned that you can't go halfway trying to clean. It's all or nothing if you want it to survive. I had a flat tappet go south in the iteration before this one. Did a .020" overbore plus a 10/10 on the crank. Oil pump. Timing set. What eventually ended up happening to that engine was loss of oil pressure to the lifters. Crap in the oil galleries or the lifter bores being steadily sand blasted by the left over grit led to the engine being unusable despite the new roller lifters and cam. It would constantly clatter like the valves weren't adjusted.
I won't make the same mistake.
But even if do go the whole nine yards rebuilding this lump, it's still a high mileage piece what with the crank and rods (all forged) ready for a pension. Even if they do crack test successfully, they're still used and maybe used up.
It's looking to get so expensive to rebuild this one that an LS is looking better and better.
But not better enough...yet.
Just remember - stresses are cumulative.
Like using aluminum connecting rods, they look great, and check great, right up until the day they snap.
Oh, and sorry for your loss. I feel your pain.
Just remember - stresses are cumulative.
Like using aluminum connecting rods, they look great, and check great, right up until the day they snap.
Oh, and sorry for your loss. I feel your pain.
Kind of my thinking as well. The odd thing is that the general consensus was that's it's unusual. There were a few anecdotal reports of having tie bars failing but for the most part it just stands out as odd. I'm going to invest in a new set of lifters but it makes me wonder if this failure is just an anomaly or if it's a bell weather into future failures.
Yeah. Kind of painful but considering I've geared myself up into buying a new short block (and before this I had considered reconditioning the current short block) and I knew the cam was toast before I found the other damage, the cost of lifters is a small percentage of what I'm investing anyway. But either way, it's gonna be spendy.
10-05-2021, 12:08 PM
