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Hydrualic Roller VS. LLR VS. Traditional Solid Roller
Hey guys,
We get many questions about this, so let me break down the pros and cons of hydraulic vs low-lash solid roller vs traditional solid roller.
First, before we go into the 3 individually, I want to talk about the lifters themselves.
The "solid" or "mechanical" valve lifter has 1 to 2 jobs. The first job is to transfer the cam lobe profile into linear, reciprocal motion to operate the valves. And, in most cases, the solid lifter also has the job of transferring oil from the pressurized oil passages to the rest of the valve train via the pushrod oil holes.
The hydraulic lifter has an additional job. It is constantly adjusting the valve train for "zero lash".
This additional feature was a great advancement for reducing the maintenance necessary.
In the early days all vehicles were solid lifter design. In the 60s, most all of the domestic manufacturers moved to "hydraulic" lifters on the great majority of their passenger vehicles. However, the performance vehicles maintained "solid" lifters. This was because engineers knew that the solid lifters were superior for performance and reliability at high RPM or severe conditions. This dynamic is still true, however a couple things have changed. Hydraulic lifters have improved and consumers have gotten fussier about convenience and quiet operation. So, now even performance vehicles have hydraulic lifters from the factory.
So, we know that what hydraulic lifters bring to the table is self adjusting valve train and low maintenance. We also know, that while this is ideal for the majority of motorists, it is not the ultimate in high performance. The reason is, that the self adjusting design of the hydraulic lifters has some weaknesses in extreme environments.
Hydraulic lifters can be upset by several things:
Fluctuations in oil temperature will affect a hydraulic lifters bleed down rate. Fortunately for your typical passenger vehicle, this is mitigated by advancements in multi-viscosity oils. Hydraulic lifters are also calibrated for a certain viscosity of oil. So, if you build an engine for high RPM with increased tolerances and/or your engine builder recommends a "thicker" oil, it is very likely that your hydraulic lifter may not be calibrated to perform as designed with the higher viscosity oil.
Aeration of oil will interfere with a hydraulic lifter's ability to maintain zero lash. This is because, unlike oil, air will compress. So, with aerated oil, the hydraulic lifters lash will be erratic and will introduce instability into the valve-train.
Load carrying and shock resistance is an additional weakness of the hydraulic lifter in comparison to a solid lifter. Aggressive cam lobes, very high spring pressures and high loads associated with high RPM can also upset the hydraulic lifters ability to maintain zero lash and valve train stability
So, on to the differences and advantages between LLR, traditional solid and hydraulic.
Outside of the lifter, the difference in the camshafts is all in the design of the cam lobes. The difference in the cam lobes is all about lash.
Here is an illustration that we can use to visualize the discussion. While it is not my illustration and does not use the exact terminology I might use, it is sufficient for the discussion:
The main difference between the 3 lobe types will be in what this illustration calls the "clearance ramp". The more "lash" or slack in the system, the more clearance ramp is needed to "take up" the lash or slack. The area of the lobe ramp is very "slow" or has very low acceleration. This slow section of the ramp is designed to slowly remove the slack from the system and gently load the valve train before the acceleration of the lifter and valve train begins.
So, the real difference between a hydraulic, LLR and traditional solid roller camshaft is in this "clearance ramp" area of the lobe. A hydraulic roller has a very small clearance ramp that mainly just accounts for deflection. The Low Lash Solid Roller has a slightly larger clearance ramp that must take up a small amount of lash (typically from .006" to about .016" or about .010" in our typical LS lobe). Lastly, the traditional solid roller has the largest clearance ramp designed to take up about .020" to .024" lash. That is it, that is the only real technical difference.
Where some get confused about this is in the typical application. In your typical applications, there are often differences in the rest of the lobe as well. Typically, hydraulic lobes need to be "softer" or have less aggressive lobes with more "seat timing" to avoid upsetting the hydraulic lifter. The traditional solid lifter will typically have the most aggressive lobes as they are generally used in racing applications where the system is designed to handle great acceleration of the valve train. The Low Lash Solid Roller is typically somewhere in between in regards to seat timing and acceleration rates. With that said, it is important to know that we can make any of these 3 lobes more aggressive or softer to tailor them to a specific application. So a low lash can be made a serious race lobed camshaft or a mild street camshaft capable of hundreds of thousands of miles of operation. Likewise, the traditional solid lifter camshafts used to come in vehicles from the factory and are every bit as capable of producing the same trouble free miles as a hydraulic lifter camshaft with the correct lobe design for that application.
How much lash is right for a given application can be determined by as simple of a parameter as expansion of the block and heads vs the expansion of the valve train. For example, your typical iron block, aluminum head LS engine will have an increase of about .004" of lash as the engine heats up from cold to normal operating temperatures. Conversely, an aluminum block, aluminum head LS engine will typically grow the lash by about .010" as the engine warms from cold to operating temperatures. So, you would set the aluminum block engine to .000" lash cold and it will open up to about .010" hot. The iron block aluminum head engine with the same camshaft will need the lash set to about .006" cold to reach .010" lash hot. This is the primary reason for lash amount selection in an LLR application. It is to account for expansion as the engine cools and warms. This is something that is not necessary with a hydraulic lifter engine because the lifter performs this task for you. Larger engines typically require even more lash to account for expansion, so a tall deck aluminum big block Chevy will need more lash to accommodate the additional expansion. There are other factors like rocker arm ratio that also play a role.
So, what is better about a low lash solid roller over a traditional solid roller? An LLR is quieter in operation over a traditional solid roller because there is less lash. In fact, many people report that their low lash solid roller cams actually operate quieter than their hydraulic lifter engine did previous to switching. This is because their old hydraulic setup was having a problem maintaining zero lash for some reason. Be it a poorly calibrated lifter, aerated oil or even contaminants in the oil interfering with the lifters oil metering. All things that do not affect a solid lifter.
What is better about a low lash solid roller over a hydraulic roller camshaft? It is all about performance and reliability. The low lash solid roller will not be upset by oil viscosity, oil aeration or more aggressive valve acceleration rates. The low lash solid roller will also have less seat timing which will make the camshaft produce more vacuum, more torque, power, drive better and handle extended RPM far more reliably than the hydraulic roller.
What is right for you? Now that you have read this, you can likely answer that for yourself:
The hydraulic roller is definitely the easiest choice. And, the hydraulic rollers are extremely capable of excellent performance to go along with their no maintenance design. A great choice for those who don't want to ever mess with their car or perhaps those with cars that are not easy to work on.
The low lash solid roller is a great choice for those who want to extract more power from their build and/or wish to extend their RPM range while still having a surprisingly low maintenance valve train. If you don't mind checking your lash maybe once or twice a year and want to really build something exceptional, the LLR might be a great choice for you.
The traditional lash solid roller is almost exclusively recommended for serious race engines these days. In these applications, a little extra valve train noise is of no concern and versatility of the additional lash and faster valve seat timing are typically desired for absolute maximum performance. However, even in serious race engines, many of our professional engine builders have started using low lash solid rollers because they tend to be easier on the valve train while still maintaining the excellent high RPM characteristics of the solid roller design.
For llsr street guys turning hi rpms like hammer is, how often do you recommend changing valve springs?
What would be a limit on how far to turn a well optimized llsr street setup?
Are there other reliability concerns with going to 8,000 rpms on a street engine?
All this is assuming that the correct lifters, rockers, etc. are used with proper wipe patterns and lash.
I'm asking for myself because I'd like to turn some hi rpms.
Lift VS. spring longevity on the street is always a trade off. I don't have a specific mileage for a given set of springs at different lifts that I can offer you as a reference. I can just tell you that as lift increases, longevity will typically decrease. I will say that I have quite a few customers who put a 1 - 2 thousand miles a year on their cars with just under .700" lift using our .750" street-strip springs. I have customers that go many more miles per year if they stick to about .650" ish lift. If you are going to run .700" ish lift on the street, it would be wise to remove a spring periodically and check the spring pressures to see how they are holding up. Due diligence can help you stay safer.
The LLSR with .653 lift in my 346 went almost 20k miles before I pulled the motor. Bottom end needs bearing refresh. I suspect it would have continued to run fine.
Hi SpeedT, sure the LS-7 uses Lash Caps on the intake with Jake's "tech" on both the IN/EX valves.
MY question was related to fitting a Solid Roller Lifter in place of a Hyd Roller Lifter in a LS-7 AND retaining the Standard Non-Adjust rockers ?
Lance
I used lash caps in all 16 valves AND used custom pushrods lengths to get the lash within 004" of perfect and used machine shims to take care of the final adjustments. Kept the factory rockers. Well, they have upgraded bushings, etc, but factory rockers
I used lash caps in all 16 valves AND used custom pushrods lengths to get the lash within 004" of perfect and used machine shims to take care of the final adjustments.
Can u pls explain this, thought lash caps are only for more contact surface to rocker arm to provide over extensive wear on valve stem itself or if using thinner stems then oem?!
And which machined shims did u mean, they are all machined to the needed height in a range of .001", can u provide a pic of them pls?
You can get - within reason - different thickness lash caps. So, you measure your pushrods with lashcaps to get it as close as you can. Err on the long side - but barely - on pr length. The shims were purchased from cam motion as a set. Thicknesses from 001 inch to 025 inch. They're just round, flat shims with ~8mm holes. They conform to the shape of the trunion. I can not provide pics because I am not home or I would.
You can get - within reason - different thickness lash caps. So, you measure your pushrods with lashcaps to get it as close as you can. Err on the long side - but barely - on pr length. The shims were purchased from cam motion as a set. Thicknesses from 001 inch to 025 inch. They're just round, flat shims with ~8mm holes. They conform to the shape of the trunion. I can not provide pics because I am not home or I would.
That's bad *** that you did LLSR and kept the OE rockers. I think the price of adjustables is probably a good part of what keeps some folks from taking the dive.
That's bad *** that you did LLSR and kept the OE rockers. I think the price of adjustables is probably a good part of what keeps some folks from taking the dive.
Thanks! I'd love to take credit for it, but I copied this guy:
It's a pretty detailed how-to for what I did. I used this method with YT non-adjustable rockers also on my 346. i actually prefer it to using adjustable rockers. It has a bit higher PITA factor on the set up side, BUT you never need to adjust it, because there is nothing to come loose. Shims are reliable
Other than saving the cost of adjustable rockers, whats the purpose for a set lash valve train that you have to putz around with shims to set. Some have stated the system is quieter. Standard setting for LS1 motors is 22 EXH and 20 on the INT. If this is too noisy for you, then tight the lash.
Also, many here believe that you will lose 10 thousandths or so in cam lift because of the valve lash. Not so. Mechanical grinds take up the lash quickly so that the advertised lift at 1/2 inch is correct as stated. Thats the real advantage to mechanical cams. Aggressive fast-opening ramps as well as high speed valve train stability, which makes more power.
Crane is going to regrind a hydraulic cam for me this summer to mechanical specs. I got a line on a set of used H&S adjustables which requires a set of 7.2 sticks for rocker clearance. The cold setting is 22, 20. Crane suggests to start there and tweak it to find the sweet spot.
This will be my 1st try with one of these. Gen 1s are set at 12, 10 or 11, 9. But, Crane states 22, 20 is the place to start on a mechanical grind for these motors. Its probably because it is all aluminum.
Other than saving the cost of adjustable rockers, whats the purpose of a set lash valve train that you have to putz around with shims to set. Some have stated the system is quieter. Standard setting for LS1 motors is 22 EXH and 20 on the INT. If this is too noisy for you, then tight the lash.
Also, many here believe that you will lose 10 thousandths or so in cam lift because of the valve lash. Not so. Mechanical grinds take up the lash quickly so that the advertised lift at 1/2 inch is correct as stated. Thats the real advantage to mechanical cams. Aggressive fast- opening ramps as well as high speed valve train stability, which makes more power.
Crane is going to regrind a hydraulic cam for me this summer to mechanical specs. I got a line on a set of used H&S adjustables which requires a set of 7.2 sticks for rocker clearance. The cold setting is 22, 20. Crane suggests to start there and tweak it to find the sweet spot.
This will be my 1st try with one of these. Gen 1s are set at 12, 10 or 11, 9. But, Crane states 22, 20 is the place to start on a mechanical grind for these motors. Its probably because it is all aluminum.
I will let you know how it goes.
I’m running a Comp solid roller with Isky red zone lifters, and Tony Mamo spec’ed adjustable Yella Terra rockers. It Is Not a LLSR camshaft, and my lash is set to .003” intake AND exhaust. An all aluminum engine will grow the lash about .010” when hot. I started at .004”, and didn’t like the noise. .003” is quiet while hot, actually quieter than my hydraulic LS stuff.
Don’t waste your time with the .020” .022” settings. It will sound like a Diesel engine.
I’m running a Comp solid roller with Isky red zone lifters, and Tony Mamo spec’ed adjustable Yella Terra rockers. It Is Not a LLSR camshaft, and my lash is set to .003” intake AND exhaust. An all aluminum engine will grow the lash about .010” when hot. I started at .004”, and didn’t like the noise. .003” is quiet while hot, actually quieter than my hydraulic LS stuff.
Don’t waste your time with the .020” .022” settings. It will sound like a Diesel engine.
Exactly! I run mine exactly zero lash cold, so it's 010 hot. If I have to err on one side or the other of zero, i will actually preload the valve 001.
.020 lash makes sense on an iron block, but you will grow lash on an aluminum block anyway, and the hotter it gets the more lash you gain.
04-10-2018, 02:03 PM
Hydrualic Roller VS. LLR VS. Traditional Solid Roller 
