Valve springs are the most highly overstressed component in the engine. That’s why they need special tender loving care. Whether it’s street, strip, circle track or any other use, the engineers at COMP Cams design each spring specifically with the application, camshaft design, engine speed and other factors in mind. A valve spring is just like a torsion bar, only wound to fit. When the spring compresses and wire twists, the outside surface of the wire is in tension and the inside of the wire is in compression. Therefore the highest stressed areas in a spring are always on the outer surface of the wire. That’s why proper handling of valve springs is critical to the surface finish and, ultimately, the durability of the spring.
We asked COMP Cams R&D Engineer, Bradley Brown, to give us some advice on the best way to handle valve springs before and during installation. Since Bradley actually designs the valve springs himself, we figured who better to ask how to maximize spring life than him? Here’s what Bradley had to say:
First, always make sure your springs are coated with a valve train assembly spray, especially if they’re going to be sitting out of the engine for a while. It’s also important to use this special lubricant on initial start-up to ensure the spring is not damaged due to friction and heat that can occur with a dry spring. Whenever you clean a spring, never use an acidic or evaporative cleaner. You don’t want the dry, uncoated or un-lubricated material exposed to air. Regardless of whether the spring is in the box or in the engine, the humidity in the air can damage them. If your spring is sitting for a long period of time, it’s heating and cooling, heating and cooling just from day to night temperature changes. As strange as it sounds, even this little change in temperature will cause moisture to develop on the spring, causing surface rust. When you put this spray on the springs, it’ll stay on, keeping them coated and lubricated.
We also recommend that engine builders wear gloves when handling valve springs to prevent body acids from creating a problem. If the oil on your hands is acidic, and you handle a spring for just a short time, you’ll see finger prints on the surface. Now that’s just a little surface rust and doesn’t look that bad, but when you shorten the life of a spring, even just a few cycles, it can cause serious problems. And the more you handle them, the more likely it is that more serious rust problems will occur.
This gets even more important with springs designed for higher stress levels, because as stress increases, the surface of the wire becomes even more critical, making the spring even more fragile than you would ever believe. Since most of the stress is on the surface, and that’s the only part we’re exposed to, we have to be super gentle with it. Always inspect the surface of the spring. If you see even the beginnings of rust or corrosion, a much more serious issue can develop. Never use a spring with rust on it, because if you see rust on the surface, it’s pretty much guaranteed to be deeper than you think. You can’t just wipe it off.
Realistically, the best thing you can do is just handle springs as little as possible and as delicately as possible to avoid damaging them. Springs can take a lot of abuse in an engine because they are designed for compression strictly in one plane. We design drag race springs, for example, to handle stresses in the range of 300,000 psi. That’s not related to the load of the spring at maximum lift that you would measure when installing the spring, but the actual stresses in the wire. This is a massive amount of stress and pushes right to the limit of the material and processing of the wire. When the engine is running, even in the most severe conditions, the spring is stressed in only one direction: up and down in compression, the same as the valve. This relates back to the twisting and the surface stresses we talked about earlier. If a spring is dropped or the surface is even just slightly damaged, it goes way over its design limits. If it hits something that’s harder than it, that’s going to put an indention in the spring. And that’s a stress riser, so it’s likely to fail at that spot. Also, when you drop a spring and it rings and resonates, that’s not good for the material. This is a little inside tip that a lot of people don’t realize.
There are failure prevention things you can do too. Never put a spring in a vice, tap it with a hammer or pry on it with a screwdriver. People do these things all the time when they’re trying to get the inner spring out of a set of dual springs. They look at it and think I’ll just grab a screwdriver and get that thing out. Well, we already know that the surface of the wire is where all the stress is. So if you put even just a microscopic nick on the spring surface, it’s going to fail there when it’s stressed. And prying on it with a screwdriver is a sure way to nick your spring.
But even before all of these things, one of the best things you can do to help maximize the life of your springs is to be absolutely sure that you have the correct springs and matching components. There are pages of charts in our catalog to help customers find this stuff. We’ve got the free tech line too because it really is that important to make sure that the spring is right for the application. Even though there may be many springs with the same installed and open loads, they are very different springs with different intended uses. Valve trains are designed as a system, and it’s extremely important that the spring be matched to all the other components in the system.
Another place you have to be absolutely certain of is retainers and seats. We always recommend using our retainers and our seats because we match the tolerances to ensure the correct fit. You can take our spring and put it on a retainer from another manufacturer and it’ll load the end coil if it’s got interference fit. That puts a substantial amount of stress on the end coil and it will snap right off. The other thing that happens a lot if the retainer isn’t right is that people think they can just clearance the spring with a sandpaper roll right at the end where the retainer fits into the ID of the spring. Well, it’ll break right there because you’ve just created a stress riser. So it’s real important that the seats and retainers are matched and set up correctly.
The actual installation part starts to get a little interesting because you have to make sure that whatever tool you use is not damaging the springs. I’ve seen different tools that wrap around springs and hit the coils and things like that. You always want to use the right tool for the job. Only use durable plastic tools to separate inner and out springs, and when removing springs, use a valve spring compressor designed for your engine.
Our springs are designed and manufactured for a specific number of cycles depending on their intended application. That’s part of the thinking process when we design new springs; drag race means this many cycles, circle track means this many cycles, street means this many cycles. And that’s where the stress comes into play; we know we can push the design to a certain level of stress to last this many cycles. So basically, we start with a number of cycles that a spring is intended to last, but the more the spring is damaged or misapplied in any way, the number of cycles will be drastically reduced. But when you handle the spring with the TLC we described, you’re preventing problems, and your new valve springs will last as long as they’ve been designed to.
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