Quick Hit: COMP Cams 4.0L Engine Upgrades For Jeeps

Of all the Jeep engines over the years, few come close to the respectable 4.0-liter AMC inline-six. These I6s first rolled out in 1964, and rose to prominence in the YJ and TJ Wranglers, as well as the XJ Cherokees. Heck, they could even be found in Grand Cherokees, both ZJs and WJs, from the 1990s to early 2000s.

But with age comes a loss in reliability. If you’re working on a Jeep from yesteryear with one of these straight sixes, you’re bound to want parts that keep these motors running strong. Thankfully, COMP Cams has rolled out several parts this year for the 4.0-liter. Let’s take a look at some of them and go over their features and benefits.

COMP’s High Energy timing sets offer better durability compared to stock.

First up are the High Energy timing sets. COMP offers two versions of these sets – one meant for stock to mild performance on 1999-2006 engines (PN 3237) , and the other for heavy-duty performance on 1964-1998 engines (PN 3219). The 3237 set uses a precision cast iron camshaft gear, along with a steel crank sprocket and a durable link belt chain. The 3219 set uses a wider link belt chain for less stretch, and the tooth design on both the sprocket and gear is stronger as well.

Pairing with the timing set, COMP now offers five hydraulic flat tappet camshafts for the 4.0-liter engine. All are a part of the Xtreme 4×4 family of camshafts, but fulfill different purposes depending on the application and the year the engine was made.

New Xtreme 4x4 camshafts will restore the 4.0-liter I6 to its former glory, and then some. Several options are available, and are separated by either 1964-98 model years or 1999-2006 model years.

For 1964-98 applications, three are available. One works with the stock head and EFI (PN 68-501-5), another works with an aluminum head and EFI (PN 68-301-5), and the last works with an aluminum head and carburetor (PN 68-401-5). The shape of the lobes on these camshafts provide better responsiveness and power.

For 1999-2006 applications, two are available. One works with the stock head and valve springs as well as EFI (PN 163-201-5), while the other works with an Edelbrock aluminum head and EFI (PN 163-301-5). These camshafts offer more duration and valve lift during the combustion cycle, providing greater torque and mid-range power in the engine.

New valve springs from COMP allow customers to install up to .450-inch lift camshafts in the 4.0-liter I6.

Last but not least, COMP also now offers .450-inch lift ovate wire valve springs for 1988-2006 4.0-liter engines (PN 983J-KIT). These valve springs allow customers to install up to .450-inch lift high-performance camshafts, as the springs themselves handle harmful dynamic valvetrain stress more effectively. The springs also eliminate valve float issues often found when using stock springs.

For an all-around upgrade on your Jeep’s 4.0-liter engine, you’re best served going with COMP Cams. These new parts not only restore lost power potential in the engine, but also reinvigorate it for the roads and trails ahead. Find out more about these and other COMP products by visiting the company’s website, and don’t forget to follow COMP Cams on Facebook as well.

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About the author

David Chick

David Chick comes to us ready for adventure. With passions that span clean and fast Corvettes all the way to down and dirty off-road vehicles (just ask him about his dream Jurassic Park Explorer), David's eclectic tastes lend well to his multiple automotive writing passions.
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