Camshaft end play doesn’t get nearly as much attention as lift, duration or lobe separation angle when people talk about LS1 camshafts.
But before worrying about how aggressive your cam sounds at a stoplight, there’s a more fundamental measurement worth checking:
Can the camshaft move forward and backward the correct amount?
That axial movement is camshaft end play.
According to the LS engine-building reference, acceptable LS camshaft end play is:
0.001–0.012 inch
The same reference describes checking that movement with a dial indicator positioned against the cam gear before final timing-set assembly.
Here’s what the measurement means and how it fits into an LS1 build.
What Is LS1 Camshaft End Play?
Camshaft end play is the amount the camshaft can move forward and rearward along its axis while installed in the engine.
That’s different from camshaft runout.
End play measures axial movement.
Runout measures how much the camshaft deviates as it rotates.
The LS reference lists these as separate specifications, with:
Camshaft end play: 0.001–0.012 inch
Camshaft runout: 0.002 inch maximum
Mixing those two measurements together can lead to a lot of confusion because both may involve a dial indicator, but they tell you completely different things.
What Is the Correct LS1 Camshaft End Play?
The reference specifies an acceptable LS camshaft end-play range of:
0.001–0.012 inch
During one of the book’s LS builds, the measured end play was 0.0035 inch, which falls within that range. Another documented build measured 0.005 inch.
Those example measurements aren’t new specifications.
They’re simply examples of assembled engines landing inside the stated 0.001–0.012-inch range.
Why Does an LS1 Camshaft Need End Play?
The camshaft can’t be locked solidly between two surfaces with no axial clearance.
It needs a controlled amount of movement.
The LS camshaft nose uses a stepped design. The reference explains that the smaller-diameter portion of the cam nose passes through the retainer-plate opening, while the larger shoulder prevents the camshaft from moving out of its installed position.
That arrangement establishes the camshaft’s axial location while still allowing the specified amount of end play.
In other words, the camshaft needs clearance.
It just doesn’t need a vacation.
What Controls Camshaft End Play on an LS1?
The camshaft retainer plate and camshaft nose geometry are central to controlling the camshaft’s fore-and-aft position.
The stepped nose passes through the retainer opening while its larger shoulder limits movement.
That makes the retainer arrangement very different from simply relying on the timing chain to keep the camshaft where it belongs.
When inspecting an LS engine during assembly, the retainer plate and camshaft nose therefore deserve attention before the timing cover goes on.
How Do You Measure LS1 Camshaft End Play?
The LS engine-building reference provides a straightforward procedure.
Before installing the timing chain, temporarily install the camshaft gear onto the camshaft nose.
The reference’s measurement procedure temporarily tightens the three cam-gear bolts to 20 ft-lb for the end-play check.
Then:
- Position a dial indicator against the face of the cam gear.
- Push the camshaft fully rearward.
- Preload the dial indicator approximately 0.050 inch.
- Zero the indicator.
- Pull the camshaft forward using the cam gear.
- Record the total movement.
That movement is the camshaft end play.
Compare the result with the specified:
0.001–0.012 inch.
This is much more useful than grabbing the cam gear and declaring, “Yeah, that feels pretty tight.”
We’re measuring thousandths of an inch here. Your fingertips did not come calibrated from Mitutoyo.
Why Is the Cam Gear Installed for the Measurement?
Installing the cam gear gives you a practical surface for both moving the camshaft and positioning the dial indicator.
The PDF specifically instructs the builder to place the dial indicator against the face of the cam gear.
The cam gear also gives you something accessible to pull forward after the camshaft has been pushed rearward against its axial limit.
The difference between those two positions is the measurement you’re after.
What Happens If LS1 Camshaft End Play Is Too Tight?
The LS reference gives us an important warning here.
It states that if camshaft end play is less than 0.001 inch, the cam may bind when subjected to heat during engine operation.
That’s why zero clearance isn’t the objective.
An engine’s dimensions don’t remain completely static as temperatures rise. Components expand as the engine reaches operating temperature.
A camshaft that seems perfectly happy while you’re rotating a cold engine on a stand may not remain happy when everything gets hot.
The specification provides room for that operating environment.
What If LS1 Camshaft End Play Is Greater Than 0.012 Inch?
A measurement above 0.012 inch falls outside the acceptable range stated in the LS reference.
The PDF passage establishes the specification but does not provide a universal troubleshooting tree for excessive LS1 camshaft end play.
That means we shouldn’t invent one.
If the measurement is excessive, inspect the components responsible for locating the camshaft, including the camshaft nose, retainer arrangement and any aftermarket timing components being used.
The important first step is establishing that the assembled measurement is actually outside specification.
Does an Aftermarket LS Timing Set Change Camshaft End Play?
It can change what needs to be present when you measure it.
The LS reference specifically notes that some aftermarket cam gears include a thrust bearing mounted behind the cam gear.
If the timing set uses that design, the bearing spacer must be installed on the cam gear before checking camshaft end play.
One documented aftermarket timing setup in the book uses a Torrington-style bearing positioned between the cam retainer plate and cam gear.
That’s an important detail.
If the thrust-bearing hardware is part of the finished assembly but missing during measurement, you aren’t necessarily measuring the configuration the engine will actually use.
Always check the instructions supplied with the timing set.
Is LS1 Camshaft End Play the Same as Crankshaft End Play?
No.
Your LS1 contains two different rotating components with two different axial-clearance specifications.
The LS reference lists:
| Measurement | Specification |
|---|---|
| Camshaft end play | 0.001–0.012 in. |
| Crankshaft end play | 0.0015–0.0078 in. |
Both describe axial movement, but they’re measured on different components and controlled by different parts of the engine.
We’ve covered the second measurement separately in our LS1 Crankshaft End Play guide, which is worth linking here rather than duplicating that topic. The current Pro Street article likewise establishes the crankshaft’s 0.0015–0.0078-inch range.
Is LS1 Camshaft End Play the Same as Camshaft Runout?
No.
This is another important distinction.
Camshaft end play measures forward-and-backward movement.
Camshaft runout concerns deviation as the camshaft rotates.
The LS specifications in the reference list a maximum camshaft runout of:
0.002 inch
while the end-play specification remains:
0.001–0.012 inch.
Those numbers shouldn’t be substituted for one another.
What Is the LS1 Camshaft Journal Diameter?
The same LS specification table lists camshaft journal diameter at:
2.164–2.166 inches.
That specification is useful when inspecting the camshaft, but journal diameter isn’t what you’re measuring during an end-play check.
End play is strictly the camshaft’s axial movement.
Keeping the terminology specific helps prevent this FAQ from turning into another generic camshaft specification chart.
Be Careful Installing the Camshaft
The LS reference also provides an important warning about physically installing the camshaft.
It recommends carefully guiding the camshaft into the block to avoid nicking or scratching the cam bearings. A fore-and-aft scratch in a cam bearing can reduce oil pressure.
The book recommends using a temporary camshaft installation handle attached to the cam nose because the added leverage makes it easier to keep the camshaft straight while feeding it through the bearings.
That’s worth remembering because checking perfect end play after gouging a cam bearing during installation would be a spectacularly backwards victory.
When Should You Check LS1 Camshaft End Play?
The reference performs the measurement before final installation of the timing chain.
That timing makes sense because the cam gear can be temporarily installed, used for the dial-indicator measurement and then removed so the timing set can be assembled.
For a performance engine, this is also the ideal point to discover a problem.
The timing cover isn’t installed.
The accessories aren’t installed.
And the engine isn’t sitting between the frame rails where every simple job suddenly requires removing six unrelated components.
Don’t Assume a New Camshaft Has Correct End Play
A new camshaft doesn’t guarantee the finished assembly has the correct axial clearance.
The measurement represents the interaction between the camshaft and the components controlling its axial location.
This becomes especially relevant when combining:
- An aftermarket camshaft
- Aftermarket timing gear
- Double-roller timing set
- Thrust bearing or spacer
- Replacement cam retainer plate
The PDF’s warning about installing the aftermarket cam-gear thrust bearing before measuring end play illustrates exactly why the assembled combination matters.
Measure the engine you actually built.
Not the engine the parts catalog promised you were building.
Check LS1 Camshaft End Play Before Closing the Engine
Camshaft end play isn’t something most people brag about when describing an LS1 build.
Nobody opens the hood at Cars and Coffee and announces:
“My cam has four thousandths of axial movement.”
Still, it’s exactly the kind of small measurement that separates assembling parts from actually building an engine.
For the LS camshaft, the reference gives us a clear specification:
LS camshaft end play: 0.001–0.012 inch
Measure it with a dial indicator before final timing-set assembly, account for any thrust-bearing hardware used by an aftermarket cam gear, and investigate anything outside the specified range before closing the engine.
Because once the timing cover is sealed, discovering you should have checked something becomes considerably less entertaining.
LS1 Camshaft End Play FAQ
What is the correct LS1 camshaft end play?
The LS engine reference specifies 0.001–0.012 inch of acceptable camshaft end play.
How do you measure LS1 camshaft end play?
Temporarily install the cam gear, place a dial indicator against its face, push the camshaft rearward, zero the gauge and then pull the camshaft forward. The resulting axial movement is the end-play measurement.
What happens if LS camshaft end play is below 0.001 inch?
The reference warns that the camshaft may bind as the engine heats during operation.
What is the maximum LS camshaft end play listed in the reference?
0.012 inch.
What is the LS camshaft runout specification?
The reference separately lists 0.002 inch maximum camshaft runout. Runout and end play are different measurements.
What is the LS camshaft journal diameter?
The reference lists 2.164–2.166 inches.
Do I need the aftermarket cam-gear thrust bearing installed before measuring?
If the timing set uses one, yes. The reference specifically says the thrust-bearing spacer should be installed before checking camshaft end play.
