When it comes to building high-performance engines, few topics spark more debate than lifter preload. Whether you're assembling a fresh LS build or fine-tuning a seasoned race motor, preload settings can make or break the way an engine behaves.

Ask any group of mechanics, tuners, or engine builders, and you'll get a dozen different opinions—all shaped by hard-earned experience, time in the shed, and real-world results.

So, why all the noise about lifter preload? And what are the practical considerations that can help you get it right?

A Quick Look at Lifter Preload Fundamentals

Most mechanics and engine builders already know that lifter preload refers to the distance the hydraulic plunger sits below its fully extended position when the valve is closed.

What really matters is how that preload is set for your specific combination. Small differences can influence valve control, idle quality, throttle response, and long-term reliability.

Get it right, and the engine stays sharp under load and across temperature swings. Get it wrong, and even the best hardware won’t perform as it should.

Why Lifter Preload Matters

Preload is a balancing act.

Set it correctly, and you’ll have a tight, stable valvetrain that holds its tune across temperature changes and RPM swings.
Get it wrong, and issues quickly follow.

Too much preload can lead to:

• Poor idle quality

• Compression loss

• Valves hanging slightly open

• Valve float at sustained high RPM

Too little preload can cause:

• Excessive valvetrain noise

• Valve gear instability at high RPM

• Accelerated wear across lifters, pushrods, and rockers

There’s no "one-size-fits-all" setting, but finding the right preload for your setup is essential for getting the most out of your build.

Why Is Lifter Preload So Controversial?

Because every engine is different, and every builder has their own way of doing things.

Variations in component selection, intended use, lifter design, and even tuning style all play a role.
Some prefer the "zero lash plus turns" method for its simplicity and repeatability. Others prefer to measure lifter plunger travel precisely using dial indicators.

Neither approach is wrong. It’s about what delivers the best results for the engine you're building.

Factory Specs vs. Real-World Adjustments

Manufacturer preload specs are a reliable starting point, especially for stock or mild performance engines.

But once you change camshafts, increase spring pressures, or push into serious RPM, those specs often need adjusting based on real-world testing and inspection.

In general:

• Street engines can tolerate more preload to maintain quiet operation over long drives.

• Race engines often benefit from tighter preload to control the valvetrain under load and high RPM.

Good builders let experience and feedback from the engine guide them—not just paperwork.

How Leading Builders Approach LS Preload

The LS engine family in particular, has some well-established benchmarks:

• Katech recommends around 0.070-inch preload for typical LS hydraulic lifters.

• Brian Tooley Racing (BTR) advises around 0.100-inch preload for LS7-style lifters.

• Rocket Industries suggests that for street-driven LS engines, aiming for 0.040–0.050-inch preload (around three-quarters of a turn past zero lash) delivers reliable results.

The common theme is positioning the hydraulic plunger near the middle of its range—giving the system room to handle thermal expansion and maintain control at RPM.

How to Set Lifter Preload

1. Zero Lash Plus Turns

The most commonly used method:

• Rotate the engine so the lifter is on the base circle of the cam.

• Adjust the rocker until you reach zero lash—no gap, no preload.

• Tighten the rocker bolt another ½ to 1 full turn to set preload.

This approach is quick, consistent, and effective for most street and mild performance builds.

2. Measuring Plunger Travel

For high-revving, high-stress engines, precision matters.

Using a dial indicator allows you to:

• Measure the exact plunger movement

• Set preload in thousandths of an inch

• Remove guesswork entirely

It’s more time-consuming but can be critical when margins are tight.

3. Start with Specifications, Then Fine-Tune

Always start with the camshaft and lifter manufacturer’s recommended preload range.
From there, adjust based on real-world running conditions—noise, idle quality, performance under load.

Engines have a way of telling you when something isn’t quite right.

Factors That Influence Ideal Preload

• Camshaft Profile:
  Aggressive lobes with steep ramps often require tighter preload to avoid lifter collapse.
  Explore our Camshaft Guide

• Lifter Type:
  Hydraulic roller lifters typically prefer more preload than flat tappet designs.

• Engine Use:
  Daily drivers prioritise smoothness and durability, while race setups focus on valve control under heavy load.

• Pushrod Length:
  Always double-check. Incorrect pushrod length can throw preload completely out of spec.
  Find pushrods for your build here

What Happens When Preload Is Wrong?

If preload is too loose:

• You’ll likely hear ticking at idle and under light load.

• Throttle response may feel soft.

• Components will wear faster due to lash impact.

If preload is too tight:

• Idle quality drops off sharply.

• Compression may leak down due to valves staying open.

• Lifters may collapse under sustained high RPM loads.

In both cases, performance suffers—and component life is shortened.

Workshop Tips for Setting Preload

• Measure Methodically:
  Especially when mixing aftermarket heads, lifters, pushrods, and rockers.

• Recheck After Break-In:
  Heat cycling can settle components. Always recheck preload after initial running.

• Use Quality Assembly Lube:
  Valvetrain protection during first start matters.
  Shop Melling Mell Lube here

The Bottom Line

Lifter preload is one of those small details that has a massive impact.

There’s no universal answer because every engine combination is different. But understanding what preload really does—and adjusting it thoughtfully—can make the difference between an engine that just runs and one that performs consistently at its peak.

At VCM Performance, we’ve seen every kind of approach in the workshop, on the dyno, and on the track.

Respect for the process, careful measurement, and a willingness to fine-tune are what separate good builds from great ones.

Take your time. Get it right. And when in doubt, let the engine do the talking.