Help with Valvesprings and valve float. Noob

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PRH said:
I’ll repost what I said the first time around.
I encourage you to read the article in the link.
You can draw your own conclusions from there.


If the valvetrain is stable, as in........ lifters not doing things they’re not supposed to....... pulling clean well into the 6000 range is no problem.

Pump gas 360 with bowl ported J heads, dual plane intake, small solid cam, comp 995’s set up at 130lbs on the seat:
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Duane,

You won't get any argument from me that a solid has more rpm potential, but concerning the article you linked to, there is no mention of anything being done to correct rocker geometry. If the geometry is not corrected for each change in lift value, it will become unstable early.

Yes, more spring rate is required for higher velocities, but if the geometry is out in left field it will be much more than necessary. Because there is no mention of any correction, I have to assume there was none, and that makes the data less accurate. The OP may need more spring, but maybe he won't. Unless the geometry is correct, he won't know for sure.
 
340Duster247 said:
Bare with me as I'm still learning... So my current comp springs are installed at 1.8 which is a seat pressure of 121#... Now the springs the cam card suggested should be installed at 1.65 and a seat pressure of 120#.
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OK, the comp springs have 120#s @ 1.75" When installed at 1.8" and a spring rate of 370 you lose 18.5#s, so now you are at 101.5 #s. Of course it is not a perfect world , so they could be less. You cannot shim these springs to gain seat pressure because you will run into coil bind. Listen to PHR on the cam and springs, and B3RE about the geometry
 
340Duster247 said:
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Im very certain it's not a fuel problem. Issue was there when I had a carb, and there with EFI. I have a very stout fuel system on the car now with a Holley digital dash that monitor s and records everything. Also when reading plugs all is good. Data logs also show fuel/AFR is where it should be.
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If you wouldn't mind, can you post a picture or two of your plugs? I'd love to take a look at them.
 
One other thing to check, make sure plug wires 5 and 7 are not touching (and have plenty of space between them). I have seen this cause a high RPM misfire on one of my old engines years ago.
 
My philosophy when it comes to dealing with valvetrain stability problems with hyd cams is simple.......
Use a spring that is absolutely positively “enough” to allow the motor to achieve the desired rpm.
If the motor still doesn’t reach the desired rpm, you need a different cam(and or lifters).
I’ve seen this situation play out countless times.

The root cause of the inability to turn high rpm is linked to how well the lifters resist bleed down.
This is why you can do nothing but swap out the hyd lifters for solids and pick up 1000rpm(if you have enough spring).
Eliminate the collapsing lifters from the valvetrain, and you eliminate the problem.

This is the case even in something like an NHRA stock eliminator motor running the OE rockers and a cam with OE lift.

Another approach is to use a cam with lobes that are slower/less aggressive, that are less dependent on the bleed rate of the lifter being optimum.
 
The motor that the dyno sheet I posted belongs to came to me because the owner was unhappy with the power, and rpm capability.
It hadn’t been on the dyno before, but the owner said it basically wouldn’t go over 5100, which was confirmed with a chassis dyno test, where the power fell off a cliff at that point.

I swapped it over to a solid cam and shimmed up the valve springs from 115 on the seat to 130.
Other than longer pushrods to fit the new solid cam & lifters, the rest of the valvetrain remained unchanged.
As you can see by the sheet...... no problems at 5100 anymore.
 
PRH said:
The motor that the dyno sheet I posted belongs to came to me because the owner was unhappy with the power, and rpm capability.
It hadn’t been on the dyno before, but the owner said it basically wouldn’t go over 5100, which was confirmed with a chassis dyno test, where the power fell off a cliff at that point.

I swapped it over to a solid cam and shimmed up the valve springs from 115 on the seat to 130.
Other than longer pushrods to fit the new solid cam & lifters, the rest of the valvetrain remained unchanged.
As you can see by the sheet...... no problems at 5100 anymore.
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I'm sure the rpm problem was improved due to the solids, but it wasn't because the lifter was bleeding down. On the contrary, it was pumping up. When the valvetrain becomes unstable, it opens up clearance. That's when the hydraulic lifter, which is under preload, does it's job and pumps up to close that clearance. Now the valves are held open because the lifter can't (and shouldn't) bleed down fast enough to recover, and the motor hits a wall where it won't rev anymore because the valves are off the seat. That's the only purpose behind an anti pump up lifter. Set it at or near zero preload, and the motor rpms better, similar to a solid. The problem with a hydraulic, is that eventually you will hit the springs natural resonant frequency and instability will occur, even when the geometry is right. A solid will drive through it, while a hydraulic will pump up and shut down. If a hydraulic could handle higher spring pressures, then the resonance would move higher in the rpm range and the engine would never see that rpm. Unfortunately, that isn't the case, and that is why a high performance engine is ALWAYS a compromise to some degree.

My point is, if the geometry isn't addressed first, the additional spring pressure is only a short term fix, because the additional stress will weaken the springs prematurely, and you now have the rpm problem all over again.

For an aggressive 218@.050 iron emissions headed 360 to pull clean through 6000 with only a stock replacement lifter @.040" preload, 1.6 rockers with corrected geometry, and a cheap single spring, it had to be stable. Prior to the correction, it was popping like a Honda on a two step at 5200. There was nothing fancy in the heads to improve rpm either. 2.02" and 1.60" stainless valves with 3/8" stems, steel retainers, and 5/16" x .080" pushrod. IIRC, the valves weren't even undercut. The testing was done the same day on the same dyno, with nothing changed but the geometry and pushrod length. Was it still making power at 6000? No, but it needed to shift at 5800, so we gained 600 useable rpm just by getting the geometry right.

Again, I'm not saying it doesn't need more spring. It at least could use the springs being shimmed another .045" IF it is at a true 1.800" installed height now. But, imo springs are the second place to go, and lifters are third, unless you are planning a new cam combination anyway.
 
And yet, even when you adjust the “hi rpm” lifters to .002-.004 lash(so they can’t “pump up” and hang the valves open)...... they still exhibit the exact same problem.....and that problem disappears when the lifters are swapped for solids.
(Just like they discovered in that article).
I have done this on the dyno numerous times........ on several
different engine platforms.
Hyd flat and hyd rollers.

There’s a reason things like limited travel and Shubek style lifters exist........ and it’s because normal hyd lifters don’t cope very well with fast rate lobes, high rocker ratios, and the associated spring loads required to allow for high rpm use.

Sell him a correction kit........ see if it cures his problem.
If it does...... it’ll be his cheapest way out.
 
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Engine masters just switched out hydraulic lifters for solids to run on a hydraulic cam and it worked out pretty good.
 
Little back story about the engine build in the article I linked.......
One of my friends/customers was exchanging emails with Dulcich about that build prior to the motor being done or on the dyno.
He told me what the plan was for the cam and rocker ratio, and I told my friend it wouldn’t work.
BB with 1.7 rockers....... same as all BB Chevies, Fords, Cleveland fords.
None of those platforms respond well to fast rate hyd cams if you need to turn any rpm.
I had worked through all of that 10 years or so before that article ever came out.
 
340Duster247 said:
Weird my cam card says to use Lunati Springs part # 73949 with the rate of 363.
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FWIW.... Your cam PN is the old cam number..... like 5-10 years old. So that may be an old spring number. The catalog for at least 3 years now lists the new PN as 10200795 and lists a spring 73195 which is a dual+damper with a 402 lb rate. (Of course, the 73195 length is wrong for that head's installed height.)

IMHO, that higher rate in the current catalog reflects what PRH is saying... you're just undersprung and the length is set up wrong. 100 lbs on the seat is not much more than a factory 340 spring for an old slow ramp cam with lift in the mid .400's; you don't have much spring pressure in there when the ramp starts to really accelerate things open, which starts at under .050" lift at the lifter.

That's one spot when you really need some pressure at higher RPM's.... not for the sake of pressure by itself, but to move the spring resonant frequencies up higher and avoid getting the springs to vibrating internally as much. The dual design and dampers mitigates that somewhat, but not entirely. Those vibrations add pressure impulses into the whole valvetrain, including the lifters.
 
The dual design and dampers mitigates that somewhat, but not entirely.
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I haven’t used the OP’s particular spring in a while, so I won’t say for sure this is how they still are....... but the ones I have used had a pretty small diameter inner coil that had no interference fit with the damper.

The spring I recommended is a dual/no damper that has a slight interference between the coils.

My feeling is this....... springs aren’t going to fix it, but what it has in it now for springs aren’t adequate.

So, install springs that are.
If that proves to still be unsatisfactory, you’ll have decent springs on the heads that can accommodate a nice SFT cam.
 
PRH said:
And yet, even when you adjust the “hi rpm” lifters to .002-.004 lash(so they can’t “pump up” and hang the valves open)...... they still exhibit the exact same problem.....and that problem disappears when the lifters are swapped for solids.
(Just like they discovered in that article).
I have done this on the dyno numerous times........ on several
different engine platforms.
Hyd flat and hyd rollers.

There’s a reason things like limited travel and Shubek style lifters exist........ and it’s because normal hyd lifters don’t cope very well with fast rate lobes, high rocker ratios, and the associated spring loads required to allow for high rpm use.

Sell him a correction kit........ see if it cures his problem.
If it does...... it’ll be his cheapest way out.
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Well, we have different experiences. I didn't say the anti pump up would be equal to the improvement of a solid, only that it would improve, similar to a solid. The solid lifter will tolerate a lot more spring pressure, so obviously it can do a better job of masking valvetrain instability from poor rocker geometry. I personally won't let a motor go out the door without making sure the geometry has been addressed. I do, however, go up in rocker ratio on most of my combinations. My personal street car has a Comp XE-HL with a 1.7 ratio, and the recommended catalog spring, and it doesn't fall off a cliff or pop. No trick lightweight parts either.

Increased spring pressure is obviously going to make a hydraulic lifter compress more, and cause the plunger to fluctuate, especially with harmonics involved. But, that helps make my point of not putting on more spring pressure than necessary. Get the geometry right, and you will know how much, or little, spring pressure you really need. I had an engine builder who removed 120# of open pressure after correcting the geometry, turned the same rpm as with the heavier spring, and turned considerably more rpm on the dyno than with the heavier spring and no correction. I don't recommend that unless someone has the ability to do thorough testing to see where the limits are, and I don't even suggest pushing the limits to begin with. It's simply an example of how settling the valvetrain down requires less spring, even with a hydraulic setup. I can truthfully say, I've never had a customer tell me they didn't see a marked improvement with corrected geometry, when they had a problem with valvetrain instability prior to the change.

And finally, I don't suggest correcting geometry just to sell a kit. They aren't a big money maker anyway. I provide that insight for free, and if it comes back to me in business, and I've helped someone have a better engine, everyone is happy. If the OP has a local shop that actually knows what they are doing, he could have them relocate the rocker shafts and get the geometry right, but likely for a much higher cost. I HOPE by giving that insight people will do business with me, and the I'm sure same applies to you and the advice you share. FWIW, the OP hasn't mentioned what rockers he is running yet. It would be helpful to know all the valvetrain parts we are dealing with here.
 
PRH said:
Someone elses fun with a voodoo cam, and the resulting conversation:

FAST RAMP RATE HYDRAULIC FLAT TAPPET CAMS-GOOD OR BAD - Yellow Bullet Forums

Post #25 by Mike Jones describes the same type of thing I’ve found myself, numerous times.
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How about post #6, or #10, or even Jones in #19. Geometry, Oil, LIGHTER spring pressure, which would require good geometry to run with a lighter spring. Also, a lot of the lifter collapsing will have to do with pushrod oiling bleeding off lifter as well. That isn't usually the case in a Mopar engine.
 
Like I said, sell him the kit.

If it solves the problem, it’s his cheapest way out, and he gets the benefit of better performance without having to increase the spring loads.

Also, a lot of the lifter collapsing will have to do with pushrod oiling bleeding off lifter as well.
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But....... you said, the lifters aren’t collapsing. They’re actually pumping up.
I'm sure the rpm problem was improved due to the solids, but it wasn't because the lifter was bleeding down. On the contrary, it was pumping up.
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The lifters in that SB were set up every way under the sun by the owner trying to find some extra rpm out of it.
When I took it apart, they were set up right at “0” preload.
There wasn’t any pumping up going on with how it was when I took it apart.

I’m just pointing out that others, who should know what they’re talking about(Mike Jones).........instead of some nobody in Vermont who’s only been testing motors on the dyno since 1990(countless thousands of dyno pulls).......has also experienced lifters “collapsing”........ and the resulting loss of usable rpm at the top of the powerband......... that was solved by eliminating the collapsing lifters from the system.
 
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B3RE said:
FWIW, the OP hasn't mentioned what rockers he is running yet. It would be helpful to know all the valvetrain parts we are dealing with here.
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Yes, the OP should post this info for best advice. His lift is getting well up into the range where this may be of benefit.
 
nm9stheham said:
Thanks for the link.... this thread got me to thinking that finally there is a good reason to run a heavier weight oil..... sounds like this is it!
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Frankly, what the “preferred” oil is for hyd lifters seems to change fairly often.
 
PRH said:
Like I said, sell him the kit.

If it solves the problem, it’s his cheapest way out, and he gets the benefit of better performance without having to increase the spring loads.



But....... you said, the lifters aren’t collapsing. They’re actually pumping up.

The lifters in that SB were set up every way under the sun by the owner trying to find some extra rpm out of it.
When I took it apart, they were set up right at “0” preload.
There wasn’t any pumping up going on with how it was when I took it apart.

I’m just pointing out that others, who should know what they’re talking about(Mike Jones).........instead of some nobody in Vermont who’s only been testing motors on the dyno since 1990(countless thousands of dyno pulls).......has also experienced lifters “collapsing”........ and the resulting loss of usable rpm at the top of the powerband......... that was solved by eliminating the collapsing lifters from the system.
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That quote was in reference to a pushrod oiled lifter which doesn't apply to too many hydraulic cammed Mopars with a shaft rocker, and I did allude to "excessive" spring pressure causing compression of the plunger. When it hits a wall, especially with popping or break up, it is the valve being held open or bouncing on the seat, not just running out of cam from reduced duration because the lifters are supposedly bleeding too fast. I'm sure if you asked Mike Jones, he would stress the importance of correct valvetrain geometry, before throwing more spring at an instability problem. And you didn't mention whether you tried any adjustments to geometry to help the valvetrain instability you were experiencing. Might be worth a try sometime. Especially on that SBM, which sounds like a classic geometry issue.

Regardless, the bickering isn't helping the OP solve his problem. He has two (or three) approaches he can take, so he will have to decide what he wants to do.
 
Just to be clear, I wasn’t having any problems with that particular SB.
I didn’t build the motor.
The owner wanted it rev higher than the 5100rpm he could get out of it.
I told him my fix would be to replace the hyd cam with a SFT, and the problem would go away....... which it did(a scenario that has played out multiple times).
That motor sounded as happy as could be at 6800 with the little solid cam in it.
I made a few pulls to 7k, and it was just barely getting into some instability at that point(although you couldn’t hear it yet).
Springs set up at 130/330.

As for the lifter collapse/pump up thing......I’m tired of arguing about it.
I’ve tested it enough, on multiple platforms to be comfortable with my conclusions.
When you have the hyd lifters set up with lash......... and the motor runs into the wall at rpm...... it’s not from “pump up”....... because they can’t.
And when you swap them out for solids, with no other changes, and gain another 1000rpm+........ it’s pretty easy to figure out what the weak link in the system is.

I had a 383 show up several years ago, pretty much the same story.
Had a Hughes hyd cam in it, ported 346 heads, 1.6 rockers.
They did the heads, had their springs and rockers on it.
Ran into the wall at 5500.

I told him the same thing....... just put a solid in it and the problem will be gone.

Installed a nice street solid in it and upgraded to a suitable spring for the cam/rockers ........ peak hp at 6600.
I ran it up to 7200 for a few pulls, but it hadn’t nosed over at that point yet.
Stock rods...... so I didn’t take it any higher.
 
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nm9stheham said:
No matter... not important.... just an observation on a small factor.
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I posted a long time ago here that the only time I run a 50 grade oil with hydraulic lifters. Which means you have to open the bearing clearances up just to run that goo. But that's what the lifters wanted. Dyno testing hydraulic rollers on the dyno with a 5w30 oil and we were just fighting the pig. So I threw in some junk 20w50 we had there and the RPM came back, the valve train was much more quiet and power was up across the RPM range.

That was almost 20 years ago. That's also when I stopped using hydraulic roller lifters. I can run a solid roller on a HRT lobe and it works much better. Don't need goo for oil. Don't have to run Godzilla wide clearances.

All the cool people now tell me the "new and improved" hydraulic lifters now have "precisely machined internals" that allow precise oil control and let's you use a 30 or even 20 grade oil with them.

I'll never know because if I have to build an engine with any kind of hydraulic lifter I won't do it.
 
Anecdotal story......

I bought a new Dakota with a 3.9 Magnum in ‘93.
I used it to tow my car on an open trailer for years and years.
The valvetrain was always thrashing in that thing, right from new.
I figured...... it’s running fine, and it’s under warranty so I’m not going to worry about it.
I never drove it in the winter until 2004, and as such never worried about running thin oil in it for the cold months.
In 04 I bought a bigger truck, figured I’d start running the now 11 year old Dakota as the winter vehicle, and when the cooler weather arrived I put the recommended 5w30 in it.
Wow!! What a racket....... and it was going through it pretty regularly too.
I figured....... well, all that towing has probably caught up with it.
It was getting pretty darn noisy by the time the oil had 3000 miles on it.

The weather was starting to break, and I decided to throw some 20w50 in it to see what happened.
The thing was the quietest it had been in years.....and had quite a bit more pep too.
I only ended up driving it one more winter after that, and I used the high mileage 10w30 in it, since BITOG claimed it was the thicker of the 10w30’s.
Come spring the 20w50 went back in...... which is what I continued to run in it until I sold it a couple years ago......... still running strong.
 
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