Help me tear down and inspect my 440..

[RemCharger]

When you could get high quality lifters with tru-arc retainers, racers/performance enthusiasts set the preload at or near zero. I set my lifter preload at 0.003. I could run 7000 rpm.

Unlikely you can do this with today’s aftermarket HFT lifters. And with that, just run what you have.

In the day it was comp pro magnums( my day) and set them to .002 .004 hot

You probably had adjustable rockers though, right?

I used adjustable pushrods

Yep.

One more question .... how / why does a lower pre load allow for higher rpms

The hydraulics in the lifter eventually end up filling too much and float the valves

 

[gtxrt]

One more question .... how / why does a lower pre load allow for higher rpms

not so simple. The lifter pumps up most of the time when the valve floats so you need higher pressure valve springs. higher pressure valve springs can cause lifter bleed down which causes the valves to slam shut plus you lose valve lift and cost at least 15 HP and up to 30 HP. what about burnt valves when they don't close all the way. hyd vs solid with the same specs the solid will almost always have at least 15 more HP at higher rpms and no lifter pump up or bleed down. I don't think the .060 preload is going to help pump up .It would be closer to .030 or under for any benefit I would think.

 

[68-500]

David Vizard says he tries to run hydraulic liters at close to max preload. As long as your valve springs are sufficient it give less pump up time there for more hp at high revs. For your build I wouldn’t think twice about .110 preload.

 

[BSB67]

One more question .... how / why does a lower pre load allow for higher rpms

Let me try to put a finer point on it.

I assume you know what valve float is, is that correct? It is simply when the force of the valve train (mass x acceleration) is greater than the force of the valve spring. Essentially, the lifter loses contact with the cam lobe around max lift and then touch back down. The condition get worse as rpm goes up.

Lets do an example. Lets start with a solid lifter. Lets say the float first occurs at 6500 rpm. Although there is loss of valve train control, its not instant death at 6501 rpm. The cam will carry on, and rpm will still go up, but performance will fall off faster than normal. At some point you could start hurting parts.

In this case, think about what is happening to the valvetrain leading up 6500, say at 6200 rpm, 6300 rpm and at 6400 rpm. The force of the valve train is slowly creeping toward matching the force of the valve spring. Maybe think of it as the valvetrain is "getting light", but still in perfect control.

Add a hydraulic lifter into this scanerio. Everything else stays the same. Will it go to 6500 rpm? Maybe. But power will be down considerably because float started to occur earlier, probably at around 6200-6300 rpm. Why? Because your oil pressure (65 psi?) is adding to the force of the valvetrain, (i.e. 65 psi is pushing upward on the hydraulic lifter plunger) and the valvespring will lose control at a lower rpm. Worse yet, when this occurs, the engine oil pressure will pump oil into the lifter because there is no resistance on the lifter plunger. So now, not only does the valve train lose control, the lifter becomes "pumped up" keeping the valve from fully closing. Performance drops like a stone.

So the solution is to run the lifter plunger at zero preload. At zero preload, the lifter plunger is not fighting the valve spring, and if float does occur, the plunger has no where to go. It essentially causes the lifter to function like a solid lifter, all else being equal. This is why they say that doing this adds a few hundred rpm.

 

[Canadian1968]

Thanks for all the info ! . This exactly why I started the thread . Have a decent understanding of most operations with in the engine . I knew what valve float was but i did not exactly know how a hydraulic lifter specifically effected it .

My camshaft is advertised for power up to 6k. I never ran it to that though ( well not on purpose! ) Last time out at the track I was shifting consistently at 5k while testing out my new shift light. I know power isn't strictly decided by the camshaft . It's the whole combo at this point the biggest restriction I belive is how much air my cylinder heads can move. Hence my decision to try some port work . Now hoping my head breath a bit better and next time out I want to try pushing rpm up to 5500 range. My current setup should be quite happy where it is ? Getting shorter pushrods to change up my preload isn't not going to change anything..

 

[PRHeads]

I don’t think the other Hyd lifter pitfall has been properly addressed here.
Lifter pump up is certainly one issue to contend with, but frankly, with lifters made within at least the last 15 years or so, I feel that lifter “collapse” is a bigger upper rpm hp killer than pump up.
The bleed down rate of todays lifters just seem to be higher than stuff from years ago.

The three main contributors to the lifter collapse phenomenon are……
-higher lifter bleed down rate
-air entrained in the oil as rpm goes up
-decreased refill time with increasing rpm

So, what you have is lifters that bleed more oil in general, coupled with less time to replenish the oil into the lifters pressure chamber, and what oil is being put back in has air in it.
The lifter can’t collapse as far(less lift and duration are lost) if the plunger is closer to the bottom.
This is also the idea behind “limited travel” lifters.

This is the thought process that is behind the people touting running the lifter plungers closer to the bottom of the travel.
For this method to be functionally viable, you have to absolutely run enough spring load to avoid any lofting(float).

In the last several years we have encountered hyd lifters where the plungers have ended up stuck at the bottom of the body.
There is really only one way that can happen.
The pressure chamber has to end up basically empty.

 

[BSB67]

I don’t think the other Hyd lifter pitfall has been properly addressed here.
Lifter pump up is certainly one issue to contend with, but frankly, with lifters made within at least the last 15 years or so, I feel that lifter “collapse” is a bigger upper rpm hp killer than pump up.
The bleed down rate of todays lifters just seem to be higher than stuff from years ago.

The three main contributors to the lifter collapse phenomenon are……
-higher lifter bleed down rate
-air entrained in the oil as rpm goes up
-decreased refill time with increasing rpm

So, what you have is lifters that bleed more oil in general, coupled with less time to replenish the oil into the lifters pressure chamber, and what oil is being put back in has air in it.

This is the thought process that is behind the people touting running the lifter plungers closer to the bottom of the travel.
For this method to be functionally viable, you have to absolutely run enough spring load to avoid any lofting(float).

In the last several years with have encountered hyd lifters where the plungers have ended up stuck at the bottom of the body.
There is really only one way that can happen.
The pressure chamber has to end up basically empty.

I guess I didn’t make clear in my last post that I was referring to good lifters, but I did in post #96. Not sure going back 15 years is far enough. And also to be clear we are only talking about aftermarket Hydraulic cams/lifters for BBM.

 

[PRHeads]

There was a good example of “lifters behaving badly” in one of the Mopar mags from about 20 years ago.
Last time I looked for it I was able to find it easily.
The build was Steve Dulcichs “mild mannered mauler”, which was a 440 with Indy heads, a fast rate Hyd cam, and 1.7RR……..which basically wouldn’t rev past 5600.
A few spring upgrades were attempted with no improvement.

I won’t spoil the final results in case someone wants to read it.

https://www.hotrod.com/how-to/mopp-0510-440-engine-dyno-test/

About a year prior to that test, I’d already had that same scenario play out with my friends NHRA stocker in my search for some more rpm.

 

[gtxrt]

with hyd lifters you really can't have your cake and eat it too for high rpms. like Big Joe (Joe Sherman) said hydraulic cams are for sissies. LOL

 

[padam]

I’m using Rhoads hydraulic lifters. I set the preload to Rhoads spec .050 or .060.
I have been over 6200 plenty of times without valve float.
That is with single valve springs.
Both with non-adjustable and adjustable rockers.

 

[PRHeads]

I rebuilt a 396 BBC 20-ish years ago.
It was a rectangle port headed combo going in a 66 Impala with a 4 speed.
It was primarily a basic rebuild, but was going to use headers and an aftermarket Holley carb.
The owner wasn’t looking for anything too rowdy, and really didn’t want to have to adjust the valves……so it was decided a Hyd cam would be used.
I used a mild HFT from UD that had some slowed down lobes for engines with higher rocker ratios.
I set the heads up with single springs with 120/300 pressures.
Nice steady gains in the power curve thru about 5500, then the good times were just over.
This was prior to my enlightenment about lifter collapse, and I assumed it was float.
So for a test I swapped the springs to some duals I had here and set them up at like 145/365.

No improvement anywhere……..and I was pretty sure the motor was more unhappy after 5500 than with the single springs.
I talked the customer into going to a solid cam.
I used a smaller old school Comp 282S.
Put in yet another set of springs……Crane 99893’s set up at 125-130 on the seat/340-ish open.

Pulled strong thru 6500(as high as I took it), which is where the highest power was observed.

Satisfactory “High rpm”(means different things to different people) performance with todays HFT lifters, especially when coupled with a fast rate cam, can be a real challenge.

 

[icetech]

Just curious, since this has come up.... How are you supposed to know what spring pressure to go with if your cam card doesn't mention springs at all? And i have Hyd rollers (OEM Magnum lifters) in my motor and they are noisy and i don't trust em.. wanna swap to mech lifters when i get around to it.. And before someone mentions it.. i have had solids in the past and know they are noisy.. but they are supposed to be. My hyd. are noisy sometimes and not others...

 

[gtxrt]

my RT has a tight lash flat solid lifter with under hood padding I cannot hear the solid I have had hyd lifters that were a lot louder. my 440 Newport has a hyd fast ramp cam they are quiet but the cam was made for .904 lifter and a little softer closing of the valves.