big-block to Ken Duttweiler's dyno and outfitted it with a Comp Cams Xtreme Energy 282 hydraulic-roller cam, along with a set of World Products Merlin Jenkins oval-port iron heads equipped with a set of Comp single-wire valvesprings (PN 911), which are the standard springs recommended for this cam. It holds the valves, valve springs and the intake and exhaust runners. On the opening side of the lobe, the valve accelerates up to its greatest speed and then must start decelerating back to zero velocity at maximum valve lift. PAC Racing Springs has developed its own alloy that has been around for years and is known as ‘PACaloy.’ This is a specific spring material for the racing industry that optimizes the alloys with the mechanical properties to provide exceptional fatigue life with minimal load loss.”, He continued, “The lightweight nature of titanium is great for valvetrain parts, but the rapid development of the chrome-silicon steel alloys in the past decade have created a large decline in its use. And, in the worst cases of valve bounce, the tips of the springs can break off. Classic valve float is usually accompanied by a dramatic loss in power and an obvious misfire, but most engines are already suffering power loss from valve float before it becomes audibly noticeable. “The term ‘valve float’ is misleading, though, as it generally is assumed to be when the valve motion at peak lift exceeds what the cam/rocker can provide,” said Osborn. There are also many variations of valve springs, so it’s important to select the best coils for your application. By clicking Sign Up, you agree to the  Terms of Use. Because less mass and maximum stability is desired, a taller, smaller-diameter spring is often chosen over an equally-rated shorter, fatter spring. You can expect to see more of this kind of information in the future as valvetrain testing and experimentation continues, but don't be surprised if you begin to see valvespring pressures become more conservative, especially with the use of these new beehive type of spring designs. At higher engine speeds, the acceleration loads are so great that the lifter is no longer able to maintain the oil in the lifter cavity, pumping the lifter down. All PAC Racing valve springs are taken solid several times during the manufacturing and inspection process. On the ‘602 crate motor, we are concerned about losing the valve spring pressure when the stock springs go south. Adding larger valves means the valvespring must control additional weight, more than likely at higher engine speeds. 7 +50 ... Spring Design Stuff. Overheating can affect the spring pressure permanently. As camshafts become more aggressive in the search for more power, these lobes make life increasingly difficult for valvesprings. Special thanks can be made to the Top Fuel and Pro Mod racing engines that are ever-pressing camshaft and valvetrain limits. The eccentricity or steepness of the lobe controls how quickly it forces the valve open. Historically, load has been the main factor in matching a spring to a valvetrain, but given all the variables of rocker ratios, valvetrain weight, pushrod deflection, and a couple of dozen other items that affect valve operation, it's easy to see that matching a spring to a cam lobe and valvetrain requires much more data than just a load rating. There was only one point at 4,300 rpm where the power numbers were the same. “The most important determiner is the installed height. With solid lifters, it is advisable to always err on the side of higher rather than lower spring pressures.”, Valve float is a major problem and can be a real engine killer. Again, if the valvespring is designed, installed, and used properly, this is usually not a problem. Companies like PAC Racing Springs have sophisticated software, Spintron test equipment, and the experience to help determine the optimum spring selection.”, Jack McInnis, of Erson Cams, stated, “There are a number of factors involved in selecting the optimal valve-spring setup for your engine. This is important because we're reducing the mass at the top of the spring, which reduces lateral leverage as well. Common spring shapes are cylindrical, beehive, and conical. You never want to achieve coil bind as it can have devastating affects on your engine. We've also learned that the lifter side of the valvetrain will benefit greatly from additional stiffness, especially for pushrods (even at the expense of additional weight), while the valve side of the rocker arm will work better by reducing weight. This is especially noticeable on a Spintron test stand. This makes life much easier on the valvespring. They are rapidly cycled while being subject to great force, friction, and heat. Don’t: install springs with excessive clearance. This is a critical point, because coil springs must use a certain amount of their pressure to control themselves. Now this is the time when you start to consider which valve spring you should purchase. That load is the pressure imparted on the valve to control it. What is easily accomplished at 3,000 rpm must be completed in half the time at 6,000 rpm. “They need to have specific alloys and manufacturing methods to be able to withstand the lift and rpm to which they are subject. Other indicators of float might be when adjusting lash, noting that a rocker roller is moving around the outside edges of the valve. “The springs provide force to keep the valve in contact with the mating components during the valve opening, peak lift, and during closing events of the intake and exhaust cycles. What we need to bear in mind is that for every valve that is opening and the spring being com-pressed, another valve is closing and its valve spring is expanding. Don’t: let the springs get rusty. Roller cams drastically increase acceleration rates, especially compared to flat-tappet lifters, which means that the valvespring must now control a mass that is now moving much quicker at the same rpm. Any metalurgists, engineers, or rocket scientists here that can explain why valve springs do or don’t lose strength from being compressed over sustained periods of time. Lastly, every racer should have a tool for checking valve-spring tension. At a given rpm, any valvespring will hit a frequency where it will naturally vibrate or resonate like a tuning fork. This will ensure the valvetrain (including springs) is working well. Then, you have to ask, is the valve lash changing? “Beehive springs provide many great benefits described above. Ultimately, you are looking for the spring which best controls the valve movement in your specific application with the related components you will be using.”. This results in a loss of engine power because cylinder pressure is pushed back into the intake manifold instead of remaining in the cylinder. As you can see by the accompanying spring-pressure chart, the beehive spring offers 30 pounds more load on the seat (part of this load is due to the shorter installed height), with open pressures within roughly 5 to 10 pounds. Manley NexTek springs with unique LocCap system on GM COPO drag racing LSx cylinder head. The beehive spring does this by allowing the retainer to be smaller with less mass. Sometimes, valvetrain control can be improved by shimming the spring up to run closer to coil bind as long as it does not go past the bind height recommendations.”, McInnis added, “Indicators of valve float are when an engine goes flat or stops accelerating at the upper rpm range. If the turn count is less (as in a half-turn), there is too little preload. You have to start with knowing what size spring can you fit in the cylinder head, the installed height, and valve lift. It goes without saying that high-performance valve springs are a must in any racing application, and selecting the right coils can be the difference between making reliable horsepower and not making it to the finish line. Here's the rub. Bump the valvespring pressure up to increase control, and that additional load pushes down on that little piston inside the hydraulic lifter. Why? Jul 18, 2008 #6 Mwilson Veteran Member In a race application, no mushrooming of the valve/seat has happend due to higher seat pressure. Dyno man Ed Taylor performed the dyno test, equipping the Rat motor with the Comp 911 springs. Simple physics tells us that heavier objects require more force to accelerate, just like a heavier car requires more horsepower to accelerate. This is due in large part to the weight of a typical big-block valvetrain, which uses large, heavy, 3/8-inch-diameter valve stems. The lobe position on the cam controls when the valve is supposed to open. Increased rpm, high-lift camshafts, and increased durability are just a few reasons. There's much more to this concept that would take volumes to discuss (and frankly we don't pretend to understand all of it anyway), but it's enough to say that the beehive spring takes advantage of the physics of its design to give it much more control. The lighter retainer weight is more important with hydraulic lifters because the spring pressure must be limited for the lifters to function and survive. Amazingly, we picked up 26 lb-ft at 2,400 rpm and then 20 hp at the top end at 5,600 rpm. Reducing the weight of the valvetrain components means the valve springs can do their job with lower spring pressure, which in turn reduces stress on the entire valvetrain. It could be said that valve springs are the unsung heroes of horsepower. This is referred to as valve bounce (see Valve Motion Chart). Yet they are also one of the most oft-overlooked parts in the entire engine. Valve spring design and manufacturing has come a long way in the past few decades. The cost is typically under $200. The key is to reduce weight on the valve side of the rocker arm, because the rocker multiplies the lobe acceleration rate by the rocker ratio. This causes rapid drying and promotes the formation of rust on the surface, which can cause catastrophic failures. Generally, this will happen to the intake valve first because of its greater weight. Load is certainly still important to control valves at virtually any rpm, but it's also clear from Comp's dynamic testing and our own quick dyno flog that adding in the concept of valvespring frequency and what the entire valvetrain needs to ultimately control the valve is also very important. Simple physics tells us that heavier objects require more force to accelerate, just like a heavier car requires more horsepower to accelerate. When this happens, the spring loses much of its ability to maintain control over the valve. This is what happened to our big-block and why our engine picked up significant power at the top end of the curve. As racer demand increased over the years for more horsepower, more torque, more RPM, and more reliability, the gap between camshaft technology and valve spring technology became seemingly larger and larger. The biggest problem is identifying when the power loss occurs, because it may happen a few hundred rpm earlier than what is considered normal for a given application. Do: be careful when handling springs. At around 5,500 rpm, the engine went into serious valve float and would not rev past this point. This puts a whooping on valve springs so they are checked after every pass. This is why most single-wire valvesprings come with a flat wire damper. Again, cam companies, spring companies, or engine builders can help determine the checking frequency based on your level of racing.”, Villemure added, “How often you check springs depends on how long the springs are expected to last. “This is what is more commonly referred to as valve loft. There are a few factors that make it necessary for drag racers to run high-quality valve springs. They're on the expensive side, but work well in conjunction with header or exhaust upgrades. Do not run any springs that show signs of corrosion. Osborn agrees that an on-head spring-load tester should be used to determine if there is any load loss occurring. All logos and images are reserved. It should be matched to a new camshaft. They can go into a spring surge, which results in valve float or the springs will just break. Pro Stock engines that run 10,000-plus rpm with 1.200-inches of lift get checked after every pass, whereas a bracket race engine with 7,500 rpm limit and 0.800-inch lift cam may only need to be checked once a year. “It is OK to take a high-end spring and compress them solid. These loads should be recorded after the engine has been broken in and then checked periodically. Pro Stock cars use camshafts with lift in excess of 1-inch. The type of camshaft and lifters (hydraulic or mechanical), the aggressiveness of the cam profile, weight of the valves, and valvetrain components, rocker arm ratio, and rpm range will be determining factors. Of course, we could bolt in a new mechanical roller camshaft, but that's an expensive solution. Don’t: modify the springs by grinding the ends. A new cylinder head comes with bigger valves, intake and exhaust runners with smoother sides for better airflow. To prove this point, we bolted up a GM Performance Parts 454 H.O. As the engine runs higher RPM levels and more aggressive cam designs, this becomes harder and harder for the springs. The cylinders were fogged and all other storage considerations were followed. Even a slight amount of corrosion can grow to be a problem. This is most often referred to as valve float because the common misconception is that the lifter launches itself off the nose of the cam. Also, you may find lash tightening up due to valve stretch from impacting the seat. “With that smaller diameter, we can also use a smaller retainer – further reducing weight. We outfitted the rest of the engine with an Edelbrock Performer RPM Air Gap intake, a 750-cfm Holley mechanical-secondary carb, and an MSD distributor sparked by a 6AL box. Erson Cams / 800.641.7920 / PBM-Erson.com, PAC Racing Springs / 877.799.9417 / RacingSprings.com, Performance Springs, Inc. / 248.486.3372 / PSISprings.com. Sometimes, other considerations are present as well, such as the type of cylinder heads. We expected to see a slight increase in power above 5,000 rpm, but what we saw instead was a power increase virtually across the entire rpm band from 2,200 rpm to 5,700 rpm. Racing-engine builders have known for decades that lighter valvetrain components allow higher engine speeds without loss of valve control. These alloys have varying amounts of silicon, vanadium, nickel, molybdenum, and carbon that provide various levels of performance with tensile strengths over 300 ksi. Most springs are rated for a certain load at a given installed height. In addition, you’ll find dual and triple springs in some applications, and there are a few common spring materials, and different size and shape wire, too. “A cylinder head installed height measurement tool is also important for initial setup.” McInnis recommends some type of spring pressure gauge, these are a baseline tool and will never read exact spring pressure due to pivot length of rocker, pushrod, etc. My reply is that each spring stores energy, and for every valve that is opening another one is closing. All of these are excellent ways to reduce the mass of the valvetrain that must be accelerated, but they are also very expensive, and for the most part, race-only solutions. Interference can cause failures. The LL springs are available in four stages to allow users to select the best fit for their … “This is a bolt-in deal that on average, has seen in excess of 65 horsepower gains.” In any engine, that is a serious increase in power. When the spring loss a significant amount of pressure, the valves will start to float. Tasked with a critical job of controlling the valve train, valve springs operate in a harsh environment. This is the idea behind titanium retainers, valvesprings, and ultra-lightweight titanium valves. Err on the side of more pressure except with hydraulic or flat tappets. Many times, the engine speeds are limited by the ability of the springs to maintain this force, so they become an extremely critical component of any engine.”. Contact your spring supplier if you feel this is required. “Valve springs are extremely high-stressed components, if not the highest stressed in the entire engine,” added Osborn. Do: check to make sure the valve-spring retainer clears the rocker arm and valve-stem seal for the full lift. Add a comment | 2 Answers Active Oldest Votes. “Valve spring are just one component of the valvetrain system,” said Chris Osborn, product engineering manager at PAC Racing Springs. A few calculations go into determining the forces needed to control the valvetrain, but a lot has to do with history and experience. Do: store valve springs in a low humidity environment away from water or chemical spills. The current limit for steel valve springs … “Beehive springs have been around for a very long time (Wright Brothers Engine, 1903), and many OEM companies use them in current engines,” said Osborn. Valve springs are probably the most stressed components of an engine.. Comp then sent us a set of brand-new PN 29120 beehive springs designed specifically to address this valve-control problem on the Rat motor. Then, the valve must begin to close, accelerating up to a given speed and then back to zero again as the valve closes. Next you should determine which cams will get you to the power level that you require. All of this sounds fairly simple--and for stock engines, it is. Much of this has to do with what is called a spring's natural frequency. For several years, GM has employed a beehive-shaped spring in the LS1 engine. Determining the load and rate are more challenging questions to answer. ), and A is the cam/valve acceleration at a given engine speed. This expansion force actually returns the energy to the VALVE SPRINGS According to Lunati, these are the most powerful, factory-spring-compatible camshafts on the market, and blend ease of installation with outstanding performance. I ran those on a roller cam and they were still too stiff open - those springs you bought are 409 lb/in rate which is REALLY high for a flat tappet cam. The rust pits will create failure initiation points. Springs used in some Sportsman engines can last hundreds of passes, so racers typically inspect them after a full weekend or more. If you do decide to stick with stock and port, make sure to replace the factory valve guides as they tend to wear more quickly than in other LS designs. Beehive springs are great for most engines that have cams with 0.600-0.650-inch lift with relatively lightweight valves and moderate cam profiles. Too much loft in the wrong areas can bend valves when they contact pistons. Performance is all about pushing the envelope. The large gains also both occurred at the opposite ends of the rpm scale, with minimal changes in the middle. The lobes themselves control 4 things simultaneously. Also, carbon residue from reversion in the intake manifold, this would generally indicate prolonged problems, like you notice it after blowing up the engine. 4. That’s when we decided to change the valve springs. Engine builder Kevin Stoa adds, “You could have the best valve in the world, but if it floats it can act like a jack hammer and break.” These loads may not correlate exactly to a bench tester, but it does give a measure that can be compared run after run. Titanium is expensive with a limited lifetime, and the dual-spring designs that PAC Racing pioneered over the last decade have rivaled the weight advantage of titanium with superior life with a much more advantageous cost/run factor.”, Picking the right springs can be a daunting task. Dual or triple springs use the friction between the inner and outer springs to perform this damping action. Given the space needed to sandwich three springs into a pack, the valve spring pocket will often need to be machined just to fit the large diameter spring. If you are running a flat tappet cam there is a much better rate you could have picked. We discussed this test with Comp Cam's spring design engineer Thomas Griffin, and he attributed the increase at low speeds to the additional load pumping the lifter down slightly, which could shorten the cam's duration and boost torque. If you want to find the latest and greatest in valve spring technology, a quick look at these power-house engines will speak volumes. … Pro Stock racers will check them every round, but they don’t expect springs to last longer than four to eight passes. This tells us that Griffin's theory was worth at least 11 lb-ft of the total 26 lb-ft change. The advertised coil bind is the maximum that will be shipped.”, “Checking springs consists of pulling the valve cover, looking at the springs and everything in the valvetrain area to see if anything stands out like loose or broken parts, springs, spring tips, etc.,” explained Osborn. Compressing the sides will cause failure. It’s important to note, however, that stiffer valve springs need to be installed in the head if you plan to spin the engine beyond 3,500 rpm or run big boost. Also, have a way to change springs on the assembled engine as well as feeler gages, a flashlight to check for broken inner springs, and tools for adjusting lash. The spring also has reduced mass on the moving end. All of this has to happen very quickly, especially at high rpm. Increasing spring pressure increases the rpm and horsepower potential of the engine. Performance Roadblock #4: Rotating Assembly. Along with avoiding valve float, it’s important to prevent coil bind. And use a flashlight to look all around the springs and a magnet to see if there are any spring tips or metal in the top end of the engine. Modular fords, for example, have limited clearance for up-rated springs. Also took away valve train harmonics @ high rpm. Every additional 100 rpm may be worth an extra 20 or more horsepower on a … The valve-spring wire goes through extensive levels of inspection and control to maintain cleanliness within the steel and maintain high ductility with high-tensile strength. The best starting point to determine spring loads is from cam suppliers, spring suppliers, or engine builders who have experience with all of the components that go into a particular engine. Anyone who has been whacked by a torque wrench while turning a crankshaft can testify that the valve springs exert considerable force on the closing ramps! Of course, there are double (dual) springs, dual springs with dampers and conventional triple springs. If you just picture the environment the … In an attempt to reduce weight in the valve train, technology led us to a spring that is large in diameter at the base and tapers to a smaller diameter,” adds Clay. The amount of valve spring pressure that’s required depends on the application, the type of racing, the weight of the valvetrain components, the design of the valvetrain, and peak engine rpm. You’ve probably also noticed that on beehive springs, the wires aren’t perfectly round, but more of an oval shape, which helps increase the spring’s … When changing to a high lift Crower performance camshaft, stock springs physi-cally won’t travel the distance your Crower high lift “Springs should be compressed in a checking station or very cautiously in a bench vise to determine the exact height where all the coils touch and they become solid,” said Osborn. Spring selection is often determined by camshaft configuration, class rules, budget, and the physical room in the cylinder head (when machining is not allowed). Also, he recommends using a log book to record how many runs are on the springs and spring loads. This creates excessive lash and lost valve lift that quickly kills power. This coil-bind height number is recorded. Make sure that adequate oil is present for cooling the springs. The reduced diameter at the top of a beehive spring also provides greater spring-to-rocker arm clearance. Those springs are really stiff for a 1.25" spring, they are not the regular Z28 spring, they are the Z28 + height spring. "This needs to be done with a retainer that compresses the inner spring as well as it may go solid before an outer spring. 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So, there is a limit to the amount of valvespring pressure we can apply to control this heavy valvetrain. The Need For Increased Performance. The valve springs have a seated pressure of 70lb as opposed to 35lb from standard. While this can and does occur, the more common result of a loss of valve control is when the valve bounces as it approaches the seat. The fact of the matter is valve springs are among the most critical pieces of an engine assembly, essentially acting as the glue that holds the entire valvetrain together. Every additional 100 rpm may be worth an extra 20 or more horsepower on a highly modified performance motor. In the event of an excessive temperature/overheating event, you should always check the springs before your next outing. This is not a recommended procedure, but with a very tight 0.004-inch lash for a quick test, Comp felt we could get away with it. The first thing you should think of when buying valve springs is your future goals in terms of peak horsepower and max redline desired. Many racers have made the switch to beehive springs. Don’t: put a spring in a vise to hold them on the OD of the spring. Actually, lofting the valve can help make power if it’s in the right spot. Valve springs return the valves to the closed position when the lobe has moved out of the way. The beehive shape also uses a radically smaller and lighter retainer. Add 32 Horsepower to your ‘602 Crate Motor! But as we add variables like increased valvetrain weight and engine speed, the situation changes drastically. This number needs to positively show there is clearance. “The first step is usually to discuss required forces with the cam designer,” said Jeff Villemure, engineer at Performance Springs, Inc. “They will take into consideration the acceleration of the cam lobe, max engine rpm, and the weight of the valvetrain. All of this is corrected with matching valvetrain component selection, especially the valve springs.”, He continued, “Valve bounce degrades engine performance with dips in the power curve, which may be observed in a dyno test session. PSI inspects each spring for load and coil bind. This one test should by no means create the illusion that this new beehive spring is the ultimate solution to everyone's valvespring problems. This fix will immediately add 100 horsepower. One of the engines we have always had difficulty controlling is a big-block Chevy outfitted with a set of hydraulic-roller lifters. This damper is designed specifically to dampen the spring's natural frequency, especially when the spring resonates at an rpm where the engine spends time. But consider what happens when we add weight into this equation with a larger valve. Newton’s second law of motion, F=MA, comes into play since F is the spring force, M is the mass of the components (valves, retainer, rockers, pushrods, etc. STOCK SPRINGS In most cases stock valve springs do a good job for stock camshafts. The beauty of the beehive spring is that its conical shape and variable rate creates numerous, yet less dramatic, natural frequencies, which makes it much less susceptible to a loss of control. This was at the 432 lb-ft that was the same exact rpm where we had gained as much as 26 lb-ft. Valve springs are the unsung heroes of horsepower. The most important factors in designing a valve spring are going to be rate, free standing length (FL), coil bind (solid height), and stress. Most importantly, the beehive shape reduces the weight of the spring. These valves are 1mm larger & are an easy mod to do. Keep in mind that the top of the spring travels much greater distances and is subjected to greater accelerative forces than the bottom of the spring. The difference is the coil-bind clearance number. This is compared to the installed height and valve lift that is measured on an engine. They are one of the highest stressed components in an engine and should be handled with care. engine. This is a 2001 Chevy 350 engine that has been sitting in storage. Valve float and loss of valve control can happen even at conservative engine speeds. Given the cam's duration and lift, it should have made power at least up to 5,700 rpm, but clearly the engine was limited by valve-control difficulties.