Why do the Crane 832's need to be shimmed
 

so much to get any decent pressures out of them and other aftermarket springs come with decent pressure at an installed height of 1.8

These springs came out a while before there were many, if any good springs with the kind of pressures we need. There pretty much ancient now. They were good back then, but only usefull now if your running a smaller cam within there pressure limits.

Beast is always full of good information. Unlike others full of bullshit. :cheers:

:angel: :emb:

I'm full of bullshit myself!:cheers: But different types of cams with different lifts/durations etc. have different requirements. There's alot of factors to look at when choosing springs like seat pressure at installed height, open pressure, coil bind, Max lift before coil bind for your particular cam. You can adjust spring pressure with shims to help with those differeces in cams. I actually have pretty good success with these ancient springs on my Trex'd motor with no shims and install height of 1.750. You may be better off with another spring depending on what cam you use, such as mine, but so far so good and I know I'm not the only one. If you run after market ported heads, be sure to measure them because they may not be 1.8" install height like mine and you could end up with to much seat pressure.

Dan

i spoke with a tech from TSP about this same question. he said that for my cam (231/231, .598lift, 112LSA) that i would not need to shim the 832's. he also said that i could if i wanted to but it really wouldn't make a difference. so like stated before i think that it all depends on the cam.

At 1.75 i think the cranes are 125 lbs on the seat and 325 lbs open per crane tech support. The prc platinums for instance at 1.78 are 140-145 and 390. What is odd to me is that the cranes started off at such a weak seat pressure to begin with 112 and 300@1.8 or something like that

Here's some info on springs. The natural frequency characteristics of a spring are dependent on the physical design characteristics of the spring: i.e Wire diameter; O.D. of the spring: I.D of the spring: # of coils; # of active coils; etc. Natural frequency is NOT affected by: material of the wire or SEAT PRESSURE. Shimming a spring has zero affect on natural frequency. You shim a spring to achieve a desired seat pressure that:1. is necessary to seat the valve; 2. must work through the rocker ratio to keep the lifter on the camshaft and 3) keep the hydraulic lifter plunger centered at its proper preload position(spring pressure is working through the rocker arm to push the plunger down against oil pressure trying to pump it up..this is occurring due to flex in the pushrod).
The 144832 spring was designed to be able to be shimmed as a means of tuning the valve train (compensating for various camshaft requirements). If you start off with too high of a seat pressure, the only way to reduce it is to go to taller installed height and that is often inconvenient. Shimming is an extremely common practice in cylinder head preparation. It isn't a case of shimming is good or bad or required or not required! It is what you do to get a given valve train to work properly( no one who initially designs a given spring knows exactly if a valve job was done and the valves sunk in the seats, or if longer than stock valves are being used, or what retainer/lock combination is used. These factors all affect spring installed height and consequently seat pressure.) Now since shimming does not affect natural harmonics of the spring and it can be extremely beneficial in fine tuning a valve train, please explain to me why it is BAD!!

More info: The stock LS1 rockers (and many other aftermarket rockers) which are rated at 1.7 ratio actually start the valve off the seat( and return the valve to its seat) at a ratio of 1.54 or lower (some shaft mounts are below 1.5 bringing the valve off the seat) . Our Crane 1.7's start and return the valve at a ratio of 1.79 (during the oscillation of the rocker our rockers go from 1.79 to 1.72 and back; the stock rockers go from 1.54 to 1.69 and back). Now let's consider the affect of 130# of seat pressure with the stock rockers: 130# x 1.54 rocker ratio = 200# of pressure operating through the rocker to keep the lifter on the seat and keep the plunger positioned. With the Crane: 1.79 x 112#(@1.800 installed ht) = 200#. WoW!!! look at that!!! the same effective pressure!!! Do you see why we designed them like that guys!! With our 1.8s you would have: 1.89 x 112#=211#. With the stock rockers that would require 137# of seat pressure. One other comment here: many people have said in other threads that our "Quick-Lift" rocker geometry puts too much initial shock into the valve train. It certainly doesn't especially if you take advantage of the lower seat pressures that "Quick-Lift" technology offers!!!

FWIW, seat pressure with stock LS1 springs is about 70-75#; LS6 springs are 90-95#. Also, our springs are hardly ancient and were designed after the 918's and several others on the market. We specifically designed these springs to be extremely compatible with the stock valve weights in LS1 & LS6 engines. One thing common to virtually all LSx springs is that there will be some amount of valve lofting at RPMs above 5000. This often causes erratic dips in the power curve if the lofting is "asymmetrical" at certain RPMS. Our spring minimizes lofting as a result of rate and harmonics, but in addition, what lofting that does occur stays symmetrical to about 7000 RPM with stock weight valves. We also have seen very symmetrical lofting with light weight valves above this number. Lofting can be good (if symmetrical and the lifter lands lightly on the closing ramp) because it adds area under the lift curve, or bad (if the lifter bangs off the nose and misses most of the closing ramp) causing cam wear and noise, but it is a fact of life at some point in the higher RPM ranges of all pushrod valve trains and we try to minimize it and control it to the best of our ability. We truly feel that the 144832 valve spring is an outstanding spring for LSx engines using stock or near stock weight valves. (keep in mind that light weight valves are good for high RPM use but usually very poor at heat dissipation and consequently do not live long in general use).

Now I have given you several facts (certainly not all of the facts and considerations) about spring design. It's your money and your decision about what constitutes a good spring. We know we have a good spring, but there are certainly a lot of people out there who think they know more than they do and I am certain they can find a way to misuse it and get lousy results!!

In conclusion, it is my personal opinion that comments that judge a valve spring by it's catalogued seat pressure or the need to shim it to a given pressure for a given cam only reflect the extremely limited knowledge of the person making that comment!!

Thanks for the explanation. As for the last comment this is why I asked, to see what the reasoning there was behind these springs being desinged and built the way they are. I am not knowledgable in that area and needed to hear a more in depth answer.

I apologize for the tone of the last paragraph. I've been at this for a lot of years and when I read statements that appear to contradict what is accepted as proper procedure by virtually all respected engine builders, I get a little "off my rocker!!" . Hope the info helped.

Mark Campbell
VP, R&D
Crane Cams

Not to many understand that if your not shimming your springs at all, then its not a 100% accurate spring setup anyway. Most of these guys just want to throw them in pops locks on em and go. They think if they have to spend an extra hour doing something then it MUST not be right lol

I shimmed mine .030 for an installed height of 1.77. I didnt just slap em on and go, but from what was posted by Mark above in order for these springs to be effective they either need to be used with the crane rockers or shimmed a bit when used with the stock rockers

Mark, thanks alot for chiming in and setting this thread straight. That's good info and I'm gonna copy and paste it for future reference. I did try to explain it in my first post, but I'm no expert by any means. I only used "ancient" in my post as a facetious statement directed at the earlier post, not as dig https://ls1tech.com/forums/images/sm...gr_stretch.gif.

Dan

Its not just putting a .030 across the board, but what Mark was saying was any proffesional engine builder shims just about EVERY spring to get all the pressure correct. Dont be scared of shims, just understand what they do and watch your coil bind. We have been shimming those cranes for a couple years now, Im still surprised people put them on the average setup without it.

What springs did you used to have on there Dirk?

Mark, with given cam XYZ and a 1.7 ratio and 1.6 ratio working on the closing flank do you think both need say 200 lbs of seat pressure? I would think with a lower ratio and equivalent cam the accelerations setting the valvdown woudl be less and require less. I generally run slow closing ramps anyway and dont beleive youd need as much force to keep bounce to a min, what do you think

I had the crane 832's shimmed .030 but it was their first batch the ones without the stripe

Thanks for the clarification ! Have a great day!

Mark

Could you please clarify your question, I am not following what you mean by 1.7 ratio and 1.6 ratio working o the closing flank. The same ratio will be working on the opening and closing. They would essentially be a mirror image in operation (assuming a symmetrical lobe; most everyone grinds assymetrical lobes).

As far as pressures that are necessary, we are successfully running Rolex applications (mechanical rollers with very quick lobes) to well over 7500(I can't tell you even close to the RPM) in testing with only 100# on the seat. Spring seat pressure depends on many factors on how the lobe is ground, and it doesn't relate to how aggressive or "lazy" the lobe is..contrary to commonly held opinions!

I type in a hurry, it comes out a mess :)

Given same lobe same everything else, one motor having a 1.6 ratio rocker and another a 1.7... do you think they both need 200 lbs of cracking pressure? I would think that the lower ratio with less decelleration would need less working pressure to control the valve

Dirk, the newer Crane needs another .020 thou I beleive to get same seat pressure

Too late the PRC springs are in the car and allready have their heat cycles on em. I swapped out the cranes for the PRC springs