7 Tips To Improve Performance Valve Spring Life
Valve springs continue to be one of the highest expenses, most stressed component, and one of the most misunderstood products in racing and performance. While you may not have the time, or a budget for trial and error, you can use these tips as a good starting point to help keep yourself out of trouble.
1. Use a good brand. Contrary to popular belief all of the USA sold performance valve springs are really only made by three companies, and almost all of them are produced here in the USA. These three companies produce nearly 95% of all performance valve springs advertised/sold in the USA. Each company offers different levels of processing, materials, or special finishing tailored to the racing application. Ask lots of questions, dig into who actually made the spring, get details on how it is made and what they suggest.
2. Measure, Measure, Measure. No reputable engine builder would just slap a crank in without measuring the clearance and trust the manufacturer claims that it meets spec. Why just toss in a random set of valve springs when you know they are the highest stressed component in an engine? Measure the solid height, measure the distance to coil bind, measure the installed and open loads, calculate the rate. Once you get that information, compile it and make adjustments on how you set them up and run them. None of these numbers should vary in a group by more than 3% and should be even tighter if you are running things tight to bind. Measure your mating components, each valve, each installed height, each seat/shim, each retainer, label and mark each for each cylinder. You may find that you need to mix and match the retainers/valves to get the perfect installed height. If everything is matched, it may gain you some added longevity and safety margin, or at least you know if any field issues arise they are not caused by your setup.
3. System Your valve springs are part of a system. That's right, one part, one cog, of a very complicated system. If your system isn't tuned, then your valve spring certainly isn't going to be happy. This is a broad topic, but it is very important that you look into your other components, use wear marks, use temperature, use the tone of the engine to help you diagnose. Yes, an audible tone is very key and accurate to determine valve train stability. It is amazing how accurately it matches with expensive equipment people use to predict stability. Here's a list (inside a list) of things to consider a part of your valve-train system. Oil, Timing (Gear, Chain, Belt), Rockers, Bearing types (Needle/Bushing), Firing order, crank pulsations, camshaft rigidity/whip, lash, valve strength/weight, alignment angles (all of them), lifter wheel dia, camshaft profile. The list can go on and on, just check it, think about it, and dig into it if you see something concerning.
4. Camshafts There I said it, you were all thinking it anyway. Camshafts and designers hate springs. They are the sledgehammer that kills springs. That all being said, use a reputable designer and manufacturer. Manufacturing is key; a brilliant cam designer can design a fantastic cam, but it could be ground on a WW2 era cam grinder. How do you know it's ground to what was intended? Measure it! However, depending on the manufacturing process, the cam could have striations in it that can cause dynamic issues, all caused by how it was ground! A good cam designer knows the limits, has tested those limits and then backed off. This IS a never ending process, people have dedicated lives to cam design. Find those people (not the company), use a good CNC grinder, choose the right core material, rinse, wash, measure, and repeat.
5. Oiling Oiling, the critical lifeblood of an engine. Since the advent of synthetic oils, dual springs, triple springs, and dampers, the oil type plays an even larger role in valve spring life. Synthetic oils are known to fall short on protecting lifters and improving wear due to limited additives, and it has the same negative effect on valve springs. Those omitted additives provided the necessary friction modifiers to reduce fretting on nested (dual, damper, triple) valve springs. While valve springs are the highest stressed component in an engine, the very inside diameter of the coil is the highest stressed area on the spring. Incidentally this is the area where the inner springs rub and cycle up and down on. Ensuring good lubrication to the ID of the spring assembly will highly reduce the likelihood of a fretting failure due to springs rubbing together. Oil (there I said it again) also provides cooling. Thermal cycling of springs causes huge issues on drag race springs specifically. Having cool oil ensures all of the springs are being cooled, and helps improve & maintain installed loads. So, use lots of oil, make sure it actually stays where you need it, use good friction modifiers, design systems to get the oil where you need it- the inside dia of a spring. SO much time in professional race teams is spent on this aspect, it's really important and can make a huge difference with little effort.
6. RPM We all love RPM. Just hearing an NHRA pro-stocker cross the 1320 mark in 5th gear at 11,000+ was one of the greatest sounds. We all love the Indy, Nascar, and F1 cars hanging it all out there for you turny circle track guys. But hey, if RPM didn't kill parts, sanctioning bodies wouldn't crush those sounds we all love by adding stupid rules. So for those of you lucky enough to have no RPM rule, game on! This all goes back to that audible sound or measuring with a spintron or dyno. If you want to run the RPM, test it, refine it, and adjust. Ensure you have the proper spring rate. Rate matters more than load for spring surge; rate is the function of rising load per deflection, and this counteracts the applied force from the cam motion. If you have enough rate, then add some clearance to bind, allowing the spring to compensate and give it room! A spring is MOST HIGHLY stressed when it's compressed, so get enough rate, and let the spring breathe. The added dynamic surge during the valve open event can cause increases the maximum design stress of the spring, so ensuring your surge is under control will improve life. Lots of factors go into dynamic valve train control, but the key is to recognize it, use simple methods, and refine with more advanced methods as you increase your RPM.
7. Choose the right processing Springs are not all equal when it comes to material and processing. Different heat treating, finishing, alloys, polishing, and cosmetic treatments go into springs. Usually the cost of a spring directly reflects how highly stressed and what added processing goes into the spring. Manufacturers spend lots of time trying to improve the processing, which allows spring designs to advance and customers can continue to push limits and refine performance. Today, with many sanctioning bodies limiting RPM, the top tier teams are looking for other things to drive performance. They are focusing on spring longevity more than performance. Get into details, buy samples, look at them underneath a magnifying device, ask questions, look at if they lean, does the appearance match, nothing should look like it was made with a hacksaw. Does your manufacturer batch test? Do they cycle test each batch? This gets back into Tip#2 but processing varies widely between manufacturers; it's a constant game played to get the best and most STABLE process.