Installing a performance cam in your Jeep 4.0 engine changes valve timing to shift power delivery higher in the RPM range. Finding the best cam for jeep 40 can feel overwhelming with so many options on the market. This guide breaks down everything you need to know to pick the right cam for your driving style.
Your Jeep 4.0 inline-six is a legendary engine, but it leaves power on the table from the factory. A cam swap is one of the most effective upgrades you can make. Let’s walk through the top choices and what makes them work.
Why Upgrade Your Jeep 4.0 Camshaft
The stock camshaft in the 4.0 is designed for low-end torque and fuel economy. It works fine for daily driving but runs out of steam above 3500 RPM. A performance cam changes the valve timing to let the engine breathe better at higher RPMs.
You will notice a significant power increase in the mid-range and top end. The trade-off is usually a slight loss of low-end torque, but the right cam minimizes this. Many owners report a much more responsive engine after the swap.
What A Cam Swap Actually Does
The camshaft controls when the intake and exhaust valves open and close. A performance cam has more duration and lift. Duration is how long the valves stay open, and lift is how far they open.
More duration lets the engine pull in more air at high RPMs. More lift improves airflow through the cylinder head. Together, these changes can add 20-40 horsepower to a stock 4.0 engine.
Common Misconceptions About Camshafts
Some people think a bigger cam always means more power. That is not true. A cam that is too aggressive for your setup will make the engine sluggish and hard to tune. You need to match the cam to your compression ratio, cylinder head flow, and intended use.
Another myth is that you need a full engine rebuild to install a cam. While it is easier with the engine out, you can swap the cam with the engine in the Jeep. It takes some work but is doable in a weekend.
Best Cam For Jeep 40
After testing and research, the best cam for jeep 40 overall is the Comp Cams 68-232-4. This cam is designed specifically for the 4.0 inline-six and offers an excellent balance of power and drivability. It provides strong gains from 2000 to 5000 RPM without killing your low-end torque.
The Comp Cams 68-232-4 has a duration of 206/214 degrees at 0.050 inch lift and a lift of 0.450/0.458 inches. These specs are mild enough for a stock engine but aggressive enough to wake it up. You can run this cam with stock valve springs, though upgrading is recommended.
Top Camshaft Options For The Jeep 4.0
Here are the best camshafts for different needs and budgets. Each one has its own strengths and weaknesses.
- Comp Cams 68-232-4 – Best all-around performer. Works with stock ECU and injectors. Adds about 25 horsepower.
- Mopar Performance Cam – Factory upgrade from Jeep. Very reliable but mild gains. Good for towing.
- Crane Cams 753901 – More aggressive than Comp. Requires tuning and upgraded springs. Adds 35+ horsepower.
- Lunati Voodoo 10200703 – Great for high-RPM builds. Needs headers and intake to shine. Not for daily drivers.
- Howell EFI Cam – Designed for fuel-injected 4.0s. Smooth idle and good street manners.
Comp Cams 68-232-4 Deep Dive
This cam is the most popular choice among Jeep 4.0 owners for good reason. It is a drop-in upgrade that works with stock components. The power band is very usable for daily driving and off-road use.
Installation is straightforward. You need to remove the radiator, grille, and timing cover. The cam slides out the front of the engine. Plan for a full weekend if you are doing it yourself.
One thing to note is that this cam works best with a free-flowing exhaust. A cat-back system or header will help it reach its full potential. You will also want to upgrade the valve springs to prevent float at high RPMs.
Installation Tips For Comp Cams
Always replace the timing chain and gears when installing a new cam. The stock chain stretches over time and can cause timing issues. Use a quality double-roller timing set for reliability.
Lubricate the cam lobes generously with assembly lube before installation. The first few seconds of running are critical for cam break-in. Follow the break-in procedure exactly to avoid wiping a lobe.
Mopar Performance Cam Review
If you want a factory-approved upgrade, the Mopar Performance cam is a solid choice. It is the same cam used in the 4.0 High Output engines from the factory. Gains are modest at around 10-15 horsepower.
The biggest advantage of this cam is reliability. It is designed to work with all stock components and passes emissions in most states. Idle quality is nearly identical to stock, so you won’t have a lumpy idle.
This cam is best for owners who want a slight performance bump without any headaches. It is not going to set any drag strip records, but it will make your Jeep feel a bit more responsive.
How To Choose The Right Cam For Your Jeep
Selecting the best cam for your specific needs requires understanding a few key factors. Your driving style, engine condition, and budget all play a role. Here is a step-by-step process to narrow down your options.
- Determine your primary use. Daily driving, off-roading, or racing all need different cam profiles.
- Check your engine compression. Stock 4.0s have around 8.8:1 compression. Higher compression needs a different cam.
- Decide on your budget. Cams range from $150 to $400. Factor in the cost of supporting mods.
- Consider your tuning options. Some cams require a custom tune to run properly.
- Read reviews from other Jeep owners with similar setups. Real-world experience is invaluable.
Matching Cam To Engine Mods
A cam does not work in isolation. It needs to match your other modifications. If you have a stock intake and exhaust, a big cam will be wasted. The engine cannot flow enough air to take advantage of it.
Here is a rough guide for matching cams to mods:
- Stock engine – Mild cam like Comp 68-232-4 or Mopar Performance.
- Header and exhaust – Medium cam like Crane 753901.
- Port and polish head – Aggressive cam like Lunati Voodoo.
- Stroker engine – Custom grind cam designed for your specific setup.
Compression Ratio Considerations
The stock 4.0 has relatively low compression. This limits how aggressive a cam you can run. A cam with too much duration will cause low compression pressure and poor low-end power.
If you have a stock engine, stick with cams that have less than 210 degrees of duration at 0.050 inch lift. Anything more will make the engine feel flat below 2500 RPM. Higher compression engines can handle more duration.
Installation Guide For Jeep 4.0 Cam Swap
Installing a cam in a Jeep 4.0 is a moderate difficulty job. You need basic mechanical skills and some specialized tools. Here is a general overview of the process.
Tools You Will Need
- Socket set and wrenches
- Torque wrench
- Harmonic balancer puller
- Camshaft removal tool
- Timing chain set
- Assembly lube
- New gaskets and seals
Step-By-Step Installation
- Disconnect the battery and drain the coolant.
- Remove the radiator, fan, and shroud.
- Remove the grille and support bar for access.
- Remove the serpentine belt and harmonic balancer.
- Remove the timing cover and timing chain.
- Remove the valve cover and rocker arms.
- Remove the camshaft retaining plate and slide out the old cam.
- Install the new cam with plenty of assembly lube.
- Install the new timing chain and gears at proper timing marks.
- Reassemble everything in reverse order.
- Prime the oil system before starting the engine.
- Follow the cam break-in procedure.
Common Installation Mistakes
One of the most common mistakes is not properly timing the camshaft. The crankshaft and camshaft gears must be aligned exactly. Double-check the timing marks before tightening anything.
Another mistake is reusing old lifters. Always install new lifters with a new cam. Old lifters have worn patterns that will damage the new cam lobes. This is not optional.
Forgetting to check piston-to-valve clearance is another issue. Most mild cams clear fine, but aggressive cams can hit the pistons. Always check clearance with clay on the pistons.
Tuning After Cam Installation
After installing the cam, you may need to adjust the engine tune. The stock ECU can compensate for mild cams, but aggressive ones require a custom tune. Here is what to expect.
Stock ECU Adaptation
The stock ECU uses feedback from the oxygen sensors to adjust fuel trims. A mild cam like the Comp 68-232-4 usually works fine with the stock tune. The ECU will learn the new airflow and adjust accordingly.
You may notice a slightly rough idle for the first few drive cycles. This is normal as the ECU learns. After 50-100 miles, the idle should smooth out. If it does not, you may need a tune.
When You Need A Custom Tune
Aggressive cams with more than 210 degrees of duration usually need a custom tune. The stock ECU cannot compensate for the increased airflow. Symptoms include surging idle, rich or lean running, and poor throttle response.
A custom tune from a shop like HPTuners or Diablosport can fix these issues. They adjust the fuel maps and timing curves to match the cam. Expect to pay $300-500 for a proper tune.
Upgrading Supporting Components
To get the most out of your cam, consider these upgrades:
- Valve springs – Upgrade to prevent valve float at high RPMs.
- Pushrods – Check length and upgrade if needed.
- Rocker arms – Roller rockers reduce friction and increase lift.
- Fuel injectors – Larger injectors may be needed for big cams.
- Throttle body – 62mm throttle body improves airflow.
Frequently Asked Questions
What Is The Best Cam For A Stock Jeep 4.0?
The Comp Cams 68-232-4 is the best cam for a stock Jeep 4.0 engine. It offers a good power increase without requiring major modifications. It works with the stock ECU and injectors for most applications.
How Much Horsepower Does A Cam Add To A Jeep 4.0?
A mild cam like the Comp 68-232-4 adds about 20-25 horsepower. More aggressive cams can add 35-40 horsepower but require supporting mods. The actual gain depends on your engine condition and other modifications.
Can I Install A Cam In My Jeep 4.0 Without Pulling The Engine?
Yes, you can install a cam with the engine in the Jeep. You need to remove the radiator, grille, and timing cover. The cam slides out the front of the engine. It takes more time but is doable.
Will A Camshaft Affect My Jeep’s Fuel Economy?
A camshaft usually reduces fuel economy slightly because you tend to drive more aggressively. The cam itself does not significantly change fuel consumption at steady cruise. Expect a 1-2 MPG drop in mixed driving.
Do I Need To Upgrade Valve Springs With A New Cam?
It is highly recommended to upgrade valve springs with any performance cam. Stock springs can float at high RPMs, causing valve damage. Upgrade springs are inexpensive insurance for your engine.
Final Thoughts On Choosing A Cam
Picking the best cam for jeep 40 depends on your goals and budget. The Comp Cams 68-232-4 is the safest bet for most owners. It provides noticeable power gains without sacrificing daily drivability.
If you want more power and are willing to tune, the Crane 753901 is a great step up. For a factory-reliable upgrade, the Mopar Performance cam is hard to beat. Just remember that a cam is only one part of a complete performance package.
Take your time with the installation and do not skip the break-in procedure. A properly installed cam will give you years of reliable performance. Your Jeep will feel like a completely different vehicle with the right cam installed.
Whether you are crawling rocks or cruising the highway, the right camshaft transforms your Jeep 4.0. The power increase is addictive, and you will wonder why you did not do it sooner. Start with a good cam, support it with quality parts, and enjoy the results.