Home » What Is Valve Float?
What Is Valve Float

What Is Valve Float?

Valve float is an adverse condition that happens with engines when they operate at high speeds. It affects the poppet valves within the internal combustion valve train.

When the closure phase of the cam lobe profile isn’t closed correctly during that designated phase, reduced engine performance and efficiency occur.

This condition also carries with it a significant risk of damage because the pistons or valve springs come into contact with the valves, creating a catastrophic failure of the cam lobe or lifter. It’s especially problematic with roller lifters.

Although any engine can experience this issue, it’s typically seen in motorsports where rules limit how much camshaft lift is permitted.

What Is Valve Float?

Valve float occurs when a vehicle’s valve train gets out of control. It happens because there isn’t enough valve spring pressure available to maintain the system. Two types occur: loft and bounce. The first happens when the lifter comes off the cam lobe’s nose, while the second bounces from the seat.

A mild valve float issue is often felt as having power falling off quickly when you’re operating at a high RPM.

If you have a severe valve float issue, a sputtering sound typically comes from the engine when it is at peak RPM.

The issue that affects performance the most is lift. If the lifter rise, that can cause the valve spring to develop coil bind. Should you experience this problem, a broken or bent valve train could occur. It is even possible for the exhaust valve to hit the piston.

When you have a loft problem, you’ll need to increase your seat pressure.

If your valve is bouncing off its seat, the engine starts losing compression. You can correct this issue by increasing your open pressure.

In most situations, you’ll discover that new valve springs are needed to complete the repair. If you install lighter valve train parts, floating issues can also get resolved. By reducing the weight, the springs can control the valves with more accuracy.

You can use hollow stem valves, titanium valves, or titanium retainers to finish the repair, depending on the circumstances your vehicle faces.

How Does Valve Float Get Diagnosed?

When you suspect valve float is occurring, the easiest way to find out what is happening with the valve train is to test the components that can stop bouncing activities. Racing teams have implemented test rigs that use a SpinTron since the early 1990s.

One of the earliest adopters of this valve float diagnosis technique was Hendrick Motorsports.

The reason why it is the most popular option for valve float diagnosis is that the SpinTron is that it can identify and quantify a bounce issue. It can even let you know where it is happening within the engine.

If you drop a valve with the SpinTron, it won’t hit a piston and leave you with the entire bottom end blown. You just replace it and continue with the testing process.

Once you get to know how the SpinTron works, you can even start detecting issues like a broken spring that only produces minor shifts in the engine’s sound profile.

◼️ How Does a SpinTron Work?

When you start thinking about engine development, the things you don’t know are what can hurt you.

Whether you’re building a specific component, an entire engine, or evaluating a current one, hundreds of potential variables could be in that equation. The SpinTron is the only tool that allows operators to assess independently and test almost every conceivable problem that can cause valve float and other conditions to occur.

Unlike other engine testing systems you can use, the SpinTron produces live results on the screen so that you can see what happens in real-time with the potential problem. Operators can print the outcomes immediately or store the data for future analysis.

A SpinTron can also perform component failure analyses, provide frictional HP checks, and run durability tests on an engine. It is one of the few items that can take almost all the guesswork out of engine programs or diagnosis.

A high-powered electric motor spins the valve train and crankshaft on an engine once the SpinTron gets connected. An advanced laser camera tracks pushrod behavior and valve motion, transmitting the data to the computer through bell graphs.

◼️ History of the SpinTron for Valve Float Detection

The first SpinTron was constructed for use by Hendrick Motorsports. It is the lasting legacy of Randy Dorton, who was killed in a plane crash in 2004, who was instrumental in securing the equipment for the racing team.

In the 1990s, Trend Performance had some success developing pushrods for small and big block Chevy competition engines. They wondered what the next step could be in their design evolution, which meant they needed something to test the technology’s behavior at unusually high revolution rates.

If Trend Performance could determine why and where engines would fail, it would help them develop a more consistent engine.

Although every engine component plays a role in its performance, the valve train is the most sensitive and crucial area. That’s why the SpinTron uses a laser valve tracking system (LVTS) to find, document, and record this region’s characteristics.

It measures valve bounce, spring harmonics, lifting, and pushrod deflection.

  • First, the LTVS creates a baseline valve track by tracking it at stable engine speeds, typically around 2,000 to 3,000 RPM.
  • The operator then increases the engine speed to the following RPM preset for the test to determine if valve float exists.
  • The SpinTron records and graphs each trace over the initial baseline to compare valve train stability at different RPM levels

Meaningful results for engine testing are obtainable with the SpinTron at speeds as low as 500 RPM. Operators can also reach a peak rate of 20,000 RPM to detect potential issues while under stressful conditions.

◼️ What Is Step Testing for Valve Float?

Step testing is a process that lets operators test a complete valve train or its various bolt-on parts at different speeds. The software spins the engine at each RPM entered during the setup phase for the test.

Once the SpinTron starts working, it will record and graph information from several sensors while the engine spins at the requested testing speeds.

It’s a practical way to test an oil pump because the equipment records flow, vacuum, horsepower, and pressure at each step.

Companies or operators can also use these features to determine the optimal performance for everything from timing sets to power-steering pumps. The RPM range is the same for these parameters as it is for valve train testing.

The SpinTron is designed to help with endurance testing, simulating hundreds of street or racing miles during a single simulation. That’s why Hendrick Motorsports was interested in obtaining this technology in the early 1990s.

During each simulation, operators can choose to test a single component, such as a spring leading to a valve float problem. You could also choose to examine an entire set, such as all 16 springs on an engine.

The design enables operators to increase RPM to real-life conditions while testing parts against each other simultaneously. It’s one of the most practical ways to test engine speed without risking a crankshaft, piston, or connecting rod failure.

None of those components are necessary to operate the SpinTron.

How to Order a SpinTron

The SpinTron is available from Trend Performance. Their catalog and pricing are subject to change at any time. If you want to purchase the device for valve float testing, you can expect to pay about $50,000 for the item.

The current Trend Performance catalog is available here.

If you live near a facility that will let you operate sessions with a SpinTron for rent, you can expect to pay about $1,500 per day to get the information you need about the engine. Although that cost seems high, it’s more affordable than other methods of diagnosing a valve float problem on a high-performance engine.

Since the cost of a SpinTron is more than the average passenger vehicle, it’s not a reasonable investment to consider for your typical non-racing repair. That’s why it is often a better choice to grab the tools you need to work on your vehicle at home.

What Are the Best Automotive Tools to Buy Today?

A trip to the mechanic can get expensive quickly. It’s not unusual for this service to cost $100 or more per hour, even if you need diagnostic work for a significant problem like valve float.

Some mechanics double the price of the parts they install, charging more than retail to get what you need for the vehicle to get back on the road.

That’s why knowing how to work on your own vehicle at home can be a profitable venture. When you have the right tools and access to wholesale parts, your repair costs can decline significantly.

Here are some of the essentials you’ll want to grab.

1. Automotive Wrenches

It helps to have a set of high-quality automotive wrenches at home for working on various repairs or maintenance needs. I’ve come to love my 62-piece METRINCH combination wrench and socket set for these general chores.

This set comes with all four screwdriver bit styles you need, a wobble extension bar, and a 3/8-inch universal joint. You get two ratchets, a 1/4-inch spinner handle, and two socket sets to use.

A third deep-style socket is perfect for working on spark plugs, hard-to-reach areas, and other tricky maintenance needs. They fit metric and standard and even handle many of your typical household to-do items.

2. Torque Wrench

Every vehicle has different torque specs. The manufacturer sets this rating, which you need to respect when taking care of maintenance or repair needs at home. It’s not just for the wheels – everything from the cylinder head to any bolted part needs a specific tightening environment.

I prefer to use the CDI Drive Computorq 3 when I need a torque wrench for a situation with my car. It uses a fixed square head style to make it a convenient option in almost any setting. It only weighs two pounds, but it gives me 20 foot-pounds of torque.

The ratcheting head on this electronic torque wrench can flex up to 15 degrees for added convenience. It’s ergonomically designed to maintain grip, offers an illuminated screen for readings, and displays real-time values in four different units.

3. Floor Jack

You need to get a vehicle in the air to work underneath it comfortably. That process starts when you have a reliable low-profile jack that reliably lifts your car safely without requiring excessive effort on your part to pump it higher.

That’s why I have the Arcan Two-Ton Quick-Rise floor jack at home. It’s a heavy piece, constructed with steel, while using dual pump pistons to raise the saddle to carry the vehicular load.

The foam handle pumper makes it fast and convenient to use, while the two-piece handle makes it easy to store or pack in the trunk.

You’ll want to review the weight tolerances for the jack before purchasing it. If you overload the product, it will start leaking fluids.

4. Air Compressor

It helps to have some pneumatics at home to work on those bolts and nuts that can get tight or locked with corrosion. Instead of cranking things by hand, start by investing in a high-quality air compressor that can power those air tools.

I highly recommend using a 20-gallon unit instead of a portable 3-gallon or 6-gallon model so that you can keep working without interruption.

The California Air Tools 20-Gallon Steel Tank Air Compressor delivers the results you need for at-home repairs. It uses a 2 HP motor to deliver 5.3 CFM at 90 PSI. It has enough power for a sander or spray gun, and the operational noise is significantly less than you’ll find with similar models of this size.

If you prefer a smaller unit, the Makita MAC210Q Quiet Series Air Compressor is a functional alternative. It handles smaller jobs well and offers an oil-free design that ensures you have a maintenance-free operation.

Do I Need to Worry About Valve Float?

The average driver rarely needs to worry above valve float. If you drive a high-performance sports car that achieves high RPMs when stomping the accelerator, it could be a problem in some circumstances.

For everyone else, the cost of this problem means it would be cheaper to replace the engine in a standard car.

We all can use high-quality automotive tools to keep our engines healthy and cars on the road or track. Although most people don’t need a SpinTron to manage a valve float situation, a great set of wrenches, sockets, and more is helpful for general maintenance.

With today’s YouTube tutorials, you can learn how to change the oil, remove a fuel tank, and perform most repairs at home. That means you can save some money, have fun with the work, and possibly fall in love with your vehicle in entirely different ways.


Attention: You have to take care of your own safety and health. The information on www.vehicletrooper.com only serves for learning and entertainment purposes and is not intended to serve as a substitute for the consultation, diagnosis, and/or medical treatment of a qualified physician or healthcare provider. Before you use any equipment or vehicle, make sure you have been properly instructed by an expert and adhere to all safety precautions. This site is owned and operated by Media Pantheon, Inc., Media Pantheon, Inc. is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for websites to earn advertising fees by advertising and linking to Amazon.com