Alright. Someone has to give me the correct info. I'm getting so many conflicting opinions about spring pressures with a hydraulic roller cam that it starting to annoy me. My cam is a 228/232 dur. with .529 lift. I just want to do buy the right parts but I can't seem to find any matching info. My cam company recommends 130# seat and anywhere from 280-320# open @ .530 lift and anything more than 340# open hurts power. I have a few engine builders on another site saying that I need about 340 to keep the lifter on the cam. I have the guy on this site that says 340-350 is a huge amount of pressure for a roller cam. I have Crane cams telling me 120# seat and 340-350#s open pressure is ideal for rollers. I have my cam company telling me 120# seat doesn't cut it and this 340-350..again...hurts power by collapsing the lifter and making the lift look smaller to the engine.
Whats the correct info??!!?

I want to buy Trick Flow 175cc heads that have 3 spring options. Option 2 is a spring thats 120#seat and 319#@ open @ .530 but I assumed the 120# seat was too weak. HEEEEELLLLPPPP!!!

 

I don't think you realize how close all of those numbers you're giving there, actually are.

Keep in mind that what people are telling you for their open pressure, doesn't necessarily take your lift into account. That is, you could take a spring and it has 130 on the seat and 350 open; put a cam with a little more lift under the EXACT SAME SPRINGS set up the EXACT SAME, now it's 365 open; put a cam with less lift, now it's 340 open; use 1.6 rockers with the big cam, now it's 375 open; and so on.

When you buy and install springs, the act of heat-cycling them, depending on how you do it, will produce more difference in what you end up with the 2nd day you own them, than those numbers right there are different.

What I'm getting at is, there's a level of precision in "measuring" or "specifying" the springs, that is adequate; and beyond which it becomes meaningless.

"Measure with micrometer, mark with chalk, cut with dynamite."

I'd suggest not stressing over it so much.

IMHO, any seat pressure over 120 lbs and on up to 150 lbs is fine; and any open pressure from about 325 on up to about 375 is fine. However, I would NOT want to see 120 and 375; and I would also not want to see 150 and 325. Ideally I'd be looking for about 125-135 on the seat at whatever installed height you use (which of course is yet another variable to throw into all this) and a rate of around 350 - 400 lbs per inch. That's a WHOLE LOT more meaningful way of specifying springs.

Option 2 looks too weak to me. That is, I would look for more spring, if it was my own motor. Maybe step up to option 3, if it's not too extreme; or buy the heads without springs, and put whatever your cam mfr recommends on them instead.

 

Please don't take this the wrong way because I definately appreciate your reply, but its a little confusing when you say "I don't think you realize how close all of those numbers you're giving there, actually are", but then you say that Option 2 is a little weak. Its right in the range of all of the numbers provided. If this is weak then how about Option 3. It is 125#seat, 347# open @ my lift (.529) with a spring rate of 410#. Too much? Just right?

I hope you can appreciate how confusing this is when another guy on this site says 340-350 pressure (at my lift) is way too much. Check out the post by Five7kid on my "Re-using hydraulic roller lifters" post.

 

The way to do it is to shim up the springs to get them all as close as possible. Ideally you want them all within 5-10 psi. Measure the installed height of the valve and compress the spring to that height in a spring pressure tester. Read the gauge and that will be your seat pressure. If it's less than 130# you need to add shims under the spring to get that pressure. Then double check the spring by compressing it to the height that it will be at during max valve lift. If you can't get the open pressures within 10 psi, the springs are shot. Buy new ones. This is also a good time to check for coil bind. Compress the spring to the point of coil bind in a vise and measure the length. Then add .100" for clearance, and also add the amount of valve lift. The resulting number is your minimum installed height. Let's say that number is 1.710". Once you get the spring pressures set, put the shims on the seat, the valve in the head and the retainer/locks on the valve stem with no spring. Measure the distance from the top of the shims to the bottom of the retainer and that is your installed height. If it is less than 1.710", then you will get coil bind and need to correct the problem with longer valves or offset locks. If it's equal to or more than 1.710", you're in the clear.

 

Dump the hyd roller cam and get a real roller cam with mechanical roller lifters.

Hyd roller lifters are just too heavy to get good valvetrain control beyond about 6300rpm with a spring that won't collapse the lifter plunger.

A rev kit like sold by AirFlow Research will help, but.......

All said and done a mechanical roller setup will make more power and rev higher without all the fuss.

Up to 6000rpm or so hyd rollers are good. but much beyond that and something is going to have to be compromised.
Cam lift rate, spring pressure, maximum rpm, pick one.
Kind a of a brick wall situation.
the only real way to determine what the cam needs for spring pressure and wether that spring pressure will collapse the lifter plunger and kill the top end is to dyno test it. Change parts ( different cam design or diferent springs or try a rev kit) and dyno it again.
Cost $$$'s thou to do all this dynoing and changing parts.
probabily cheaper to jsut dump it and get a well designed "SR" mechanical street roller to start with. A good "SR" mechanical cam has tight valve lash (low niose), stable valvetrtain operation and more power and rpm than any HYD roller.

 

Spun plenty of hyd rollers to 6800-7000 with no problems and no rev kit. Granted, theyre heavy, but when setup right they wont float.

 

You could try setting up your lifter preload a little different that usual if the lifter plunger is collapsing from exessive spring pressure.

Instead of adjusting the lifter so the plunger is just slightly more depressed than 0 lash at the top of its travel, set it so that it is right near the bottom of its travel in the lifter body.
Now it cannot collapse. As long as you don't get valve float
(lifter pump-up) from valvetrain separation, you should be fine.

 

Option 3 sounds better.

I wouldn't be worrying about any 6800 RPM with the cam you're using; it'll make peak HP at about 5800-5900 in a 350, so that's going to be your shift point; somewhere in that general neighborhood.

It's a VERY BAD idea to take weak or otherwise inadequate springs, especially used ones, and shim them up to some arbitrary seat pressure. The reason is, every .001" of shim you add, decreases your coil bind height by .001". So with a high-lift cam, it's actually VERY EASY to get into trouble that way, and wipe out cam lobes. In fact, that's one of the most common reasons, besides bad break-in procedure, for destroying lobes & lifters. Obviously break-in isn't as big of a deal with roller cams; but if you run a cast-core cam, instead of a billet core, you run the risk of "tracking" the cam.... which is just as destructive as rolling lobes in a flat-tappet setup. A much better idea, is to get new, correct springs in the first place, and shim them to the correct installed height; as determined by their mfr, and your own judgement.

As far as the lifter plunger "collapsing", it doesn't happen. I'll give you a good example of why:

THe EXACT SAME LIFTERS are used in SBC and BBC. Identical in every way, same part # and everything. Yet, the BB has 1.55" diameter springs, with much higher pressures. If you look at the springs Comp recommends for their bigger Xtreme Energy flat-tappet cams, it's their 930 spring; specs are 142 on the seat (1.900"), with a rate of 352 lbs / in. Multiply those pressures by the rocker ratio (1.7), you get pressures on the lifter of 241 lbs at the seat, and a rate of 598 lbs. Compare that to a typical similarly maxed-out small block spring for the corresponding application, the 987; it's 121 on the seat at 1.800" installed height, and 344 lbs / in, which with a 1.5 rocker ratio, gives pressures on the lifter of 181.5 lbs at the seat and a rate of 516 lbs / in. Now, if those lifters would "collapse" in a small block application, how is it that the identical same lifters work just fine in the big block application?

Bottom line: don't worry about your lifters "collapsing". They don't.

Incidentally, Comp recommends that same 987 spring in the above example, for their larger hydraulic rollers in a small block.

Some of us however have been known to use BB valve springs on SB heads, anyway; if you use longer valves and/or offset keepers, and machine the spring pockets out to the right diameter, they drop right in. In fact, that's STANDARD OPERATING PROCEDURE for solid rollers. But the BB springs work just fine on SB heads with hyd rollers as well, if properly set up (with 1.850" - 1.900" installed height, instead of the more typical 1.700" - 1.800").

Like I said, if I were buying those heads and getting one of those spring packages installed on them, I would go with Option 3.

However, more likely, I would buy them with the solid roller setup (longer valves and 1.55" pockets), and no springs at all; and then use 1.550" springs from Comp, Crower, Lunati, Crane, etc.

 

I'm not ever revving over 6,000. I have more of a "car show" car that might see the occasional 5800-6000RPM for 10-15 seconds during a burnout at the local events. But as far as a "drag car" goes...nope. I have a ZZ4 and I do, however, want a lot more mid to upper range pull with a big lopey idle without sacrificing my low torque. Thats really hard to find since lopey, mid-high RPM pulling cams are dogs while cruising 1500-2500 RPM on the street. So Lazer cams suggested their hyd roller that has a 228/232 dur, .529 lift and a nice lopey 106 lobe separation. He says it pulls hard from 2000-6100. But he recommended his springs. This is how all of this spring pressure talk started. I'm really on a budget so I'm just trying to see if any of the spring options on the Trick Flow 175ccs will work.


I was in the process of posting this after you had posted. I didn't read yours and then reply. Thanks for the info..

 

1.) I didn't say to shim up weak springs, nor did I say to use shims to make a weak spring have higher pressures.

2.) True, you decrease the installed height by adding shims, but he was also told how to check for coil bind. If you get into issues with coil bind then either the springs are junk and need too many shims, you've got waaay too much lift, or the installed height of the valve is way too low.

If you're building a set of performance heads you need to shim the springs. It's not a substitute for using the correct springs. It keeps everything in balance

 

I'm confused. Why would a 1.7 rocker change the seat pressure? Isn't the seat pressure the same whether you have rockers installed or not?

 

?Why would a 1.7 rocker change the seat pressure?



I'm with you on that one
Math class anyone

 

How about a lighter spring, and then use a rev kit to keep the lifter on the cam?

 

It doesn't. And I didn't say that it does.It changes the pressure the lifter is subjected to.

If you will recall or re-read, that was in the part of my post about the mythical "collapsed" lifters, explaining about how the the IDENTICAL SAME LIFTERS in other applications are subjected to far greater forces than anything you're likely to encounter in this particular build using any of the valve spring choices the original poster mentioned but yet perform flawlessly, and why that's therefore not a concern here. Not too much math there.

Someone like Dyno Don ought to understand fully about the principle involved, with no math involved beyond what I wrote.

No you don't use a lighter spring than the cam needs. Ever. Rev kit or no. The primary effect of inadequate valve springs is the valve bouncing off the seat when it closes. A rev kit doesn't help with that.

Will Lazer warranty your valve train if you use some other valve spring besides what he recommends? None of us here will, that's for sure. Your "budget" will become very sore if your motor has a problem and you have to eat it yourself. I'd suggest you ask Lazer if that spring is acceptable. They're a reputable company, I don't think they're out to shaft you or just grab more of your money; they're more trying to make sure you don't trash parts which they would then either have to eat for reasons not of their making, or suffer from possible bad publicity in the marketplace.

 

1.7 rockers will increase the open pressure when compared to a 1.5. You're compressing the spring more.

 

[Quote]
[unquote]
Multiply those pressures by the rocker ratio (1.7), you get pressures on the lifter of 241 lbs at the seat, and a rate of 598 lbs
I think you did

 

Don, will you please explain to all these people who are now laughing at you for bickering at me again, how I'm wrong aboutchanging when the rocker ratio is changed?

It's been a long time since my last physics class; several decades now. But when I last studied these matters, the general rule of things was, that if you have a Class 1 lever that increases the distance of travel against a force on one end, the lever increases the force required to operate it by an equal proportion at the other, while decreasing the amount of travel at that end. Which of course would apply to the lever in this case being the rocker arm, and the end where the motion is less and the force therefore greater, the end driven by the lifter.

Maybe the laws of physics have been rewritten? Please inform me if they have, as I wasn't notified. I didn't get the memo.

If you can't show where the laws of physics haven't been re-written, then we will agree that the statement is correct as it stands. I really don't want to argue about it any more. Arguing with you about something so basic will start making me look like a fool too, if I'm not careful.

 

Here's my $ .02 worth.
The spring you will want to use will have open pressure of 330-335#'s at your lift. Most manufacturers will show open pressures at .500, .550 etc.

Target a seat pressure of 130#. Too little seat pressure and you'll be bouncing the spring off the seat.

Springs get weak after time. When I ran a HR cam, I used Comp 987 springs. I would change them out almost annually because they got weak and would float above 6200. The AFR Hydr-rev kit works but is not necessary if your spinning the motor 6000 rpm max.

By the way, what intake are you running? A lsa of 106 sounds tight if it's computer controlled.

www.geocities.com/dzperf

 

Sofakingdom,

I'm not to worried about Lazer taking advantage of me, its just that his spring recommendation was a spring that was 284 lbs open pressure at the cams max lift. He said 280 to 320 is ideal but I've yet to see one person (engine builder or not) agreee with 284lbs.

HiTech5,

Thats the exact pressures that I'm looking for but I can't seem to find a 1.43-1.47"OD spring with those pressures and will go to .530lift. The Trick Flow spring is 125/347. Comps has some close specs but they max out at .500 lift.
By the way, I'm running a ZZ4 crate engine with an Edelbrock RPM manifold.

 

IMO 284 is too low.

If you work out my formula against your cam lift, it comes out similar to HiTech's numbers. Those are essentially what you should shoot for IMO.

Did I say "IMO" enough?

 

If anyones bored I'd sure appreciate a part# of a spring with those numbers, is 1.43-1.47 and handles .530 lift.

I can't find one unless I shim Option 2 .030
(129.6/338)

Can I get by with Option 3? 125/347?

 

Comp 987, set up at 1.785" (1.800" and add a .015" shim)

Or, Option 3 looks entirely close enough, to me.

 

The physics are correct, until you calculated the rate at the lifter of 598# for the 930 spring. That would be 1017#. Same applies to the other spring.

 

Not to fuel the fire, and I'm no expert on valvetrain design, but the seat pressure isn't seen at the lifter because the force is being applied to the valve seat until the valve is opened a tad, THEN it sees seat pressure of spring * actual rocker ratio at that angle (so you're both right). It doesn't really matter for lifter collapse there anyway though, I'd imagine. Only the pre-load is seen at the cam during closed valve.

Shawn-
Are you putting the 175cc heads on a 350? Did you get some sort of deal on them? Why not the 195cc?

 

I have to agree with sofakingdom and his math.
The valveseat pressure is the #1 most important spec besides making sure there is no spring binding.

The open pressure and/or lifter collapse is secondary and doesn't become a factor for 99% of people out there.

120 lbs on the seat is more than enough for most SBC's on the street to a little past 6000 RPM, unless you have unusually heavy valves, or valve-stem galling.

 

_____________________________________________
I think you took care of that part yourself.

Possibly you have seen the error of your ways after rereading your post....maybe not?