Like the Jeep I-6, the factory 304 V-8 is a good starting point in a CJ, even in its stock form. The messy emissions controls and equipment of the 1970s stifled the small V-8, but with a little help this engine can provide plenty of low-end torque and some extra horsepower to make the Jeep feel like a muscle car. Swapping an AMC 360 or 401 is a bolt-in job and can provide a larger boost to the Jeep than might be possible with the 304. The AMC V-8 has a fair amount of aftermarket performance parts available, and finding a proven combination is not a difficult task.
The Generation 3 or Tall Deck AMC V-8 was used from 1970 until 1991 and was available in 304-, 360-, 390-, and 401-ci configurations. These engines share most components such as cylinder heads, intake manifolds, camshafts, etc. A 304 or 360 are probably the most common and easiest to find. Both provide a good start to a Jeep engine build.
A few varieties of the high-output electronic ignition systems are available for I-6, including a less common but effective Ford TFI conversion. This system uses a more modern ignition system with a similar function and performance to the GM HEI system. The TFI conversion uses some of the stock components while most importantly replacing the Ford Duraspark module.
Even stock, the AMC 304 has plenty of torque for the Jeep. This restored 1978 Golden Eagle CJ-7 is still powered by the stock engine attached to the factory TH400 and Quadra-Trac. A set of fenderwell headers is about the only performance addition.
V-8 Stroker
Unlike the I-6, the AMC V-8 engine has few stroker options available, built mostly of homegrown combinations using mixed parts and special crankshaft grinds. The cost and compromise may make it not worth it for a Jeep used on the street and trail. Power and torque gains found in the I-6 stroker make the work make more sense. In contrast, the AMC V-8 running in its factory sizes serves the Jeep easily, even with light modifications. I suggest you skip this option; it’s just not worth the effort to stroke an AMC V-8 for a CJ.
V-8 Induction System
The stock AMC V-8 used a Motorcraft 2-barrel carburetor that was surprisingly well suited for both on- and off-road use. These carburetors were well known for reliability and maintenance-free use. A variety of intake manifolds were used on the CJ V-8; design differences were often to accommodate emissions systems such as exhaust gas recirculation (EGR).
A shiny new Edelbrock Performer intake manifold provides the perfect performance enhancement for a V-8 in a Jeep. This AMC version is destined for Bryan Sterner’s 1980 CJ-7 that is running the stock 304. A proper-size 4-barrel carburetor and matching Edelbrock Performer camshaft completes the package.
Companies such as Edelbrock, Offenhauser, and Weiand make performance manifolds for the AMC V-8; most are made to work with 4-barrel carburetors and can be adapted to work with modern throttle body fuel-injection systems. The Edelbrock Performer series intake with its matching camshaft make an excellent combination to make some extra torque and horsepower from the engine that is nearly perfect for an on- and off-road Jeep. Most aftermarket manifolds can be purchased with or without emissions capabilities.
A small (470 to 670 cfm) 4-barrel carburetor or throttle-body fuel-injection system added to a V-8 running an aftermarket intake and cam provides better throttle response and starting. Two excellent carburetors for use in a Jeep are the Edelbrock Performer and the Holley Truck Avenger. When either is combined with the combination above, optimum performance on- and off-road can be achieved.
Holley carburetors have always been known for their exceptional performance, except when used off-road. The front and rear fuel bowl combined with the bowl venting location often caused fuel to dump into the throttle body when ascending or descending hills, resulting in flooding and stalling. Holley answered the call of off-roaders with a specially designed off-road carburetor called the Truck Avenger, featuring special metering blocks and off-road crossover vent tube.
The Edelbrock Performer Series carburetors are based on the Carter AFB and come in a variety of flow capacities. The integrated side-bowl design of the carburetor makes its off-road performance excellent compared to most other performance carburetors. The pre-tuned bolt-in design makes this a popular aftermarket carburetor.
The Edelbrock carburetor is based on the Carter 4-barrel but is specially tuned for the Performer Series products. The integrated main body side bowls and simple design make this very effective in a Jeep, especially off-road.
The Holley Truck Avenger is based upon the Holley 4160 with several modifications to make it perform in off-road conditions. Most notable is the crossover vent tube to prevent flooding on ascent and descent and spring-loaded needle and seat to control fuel flow. The Holley Truck Avenger is available in three CFM sizes. A 470-cfm suits the 304 and a 670-cfm suits the 360 and 401. Avoiding the tendency to over-carburete an engine; using the 770-cfm pays off in the form of performance and no tearing eyes from fumes.
Holley, Howell, and MSD produce electronic throttle body fuel-injection systems that replace the carburetor and can provide a high level of all-around performance, most notably in off-road conditions and starting in both cold and hot environments. These systems can operate with full, minimal, or no tuning; often through the use of the many sensors, the system tunes itself constantly while operating. A small drawback of these systems is the complexity of installation and the added potential points of failure.
Throttle body injection (TBI) systems offer a modern replacement to a traditional carburetor. The Holley Pro-Jection TBI was a popular system in the off-road community. Its simple design, easy starting, and steady engine performance at any angle were just a few of the positive features. This Holley Pro-Jection system has been running on this 350 Chevy-equipped 1985 CJ-7 for more than 20 years. Holley replaced the Pro-Jection system with the updated Holley Avenger electronic fuel injection (EFI) system.
In general these systems operate confidently, with most failures occurring with the fuel pumps. You can solve this by always carrying a spare on the trail. These systems can be expensive and the benefits may not outweigh their complexity and price.
V-8 Camshafts
A variety of camshafts are available for the AMC V-8. Many are made for strip or other racing applications, but a few exist that are perfect for the Jeep. As I mentioned before, the Edelbrock Performer Series components are nicely matched to each other. The Performer camshaft for the V-8 provides a nice power curve that increases low-end torque and mid-range horsepower. This mild build camshaft does not alter the low-end idle of the Jeep as a high-duration camshaft does, which is important when driving off-road slowly.
The small lobes and short duration on the stock camshaft in most engines made for smooth, fuel-efficient engines but at a cost to performance. Replacing a camshaft is an involved project that produces noticeable results compared to many other performance modifications. Choose a cam matched to the intake system for the best performance results. High-lift and long-duration cams sound nice but are difficult to drive off-road, as they sacrifice low-end torque for high-RPM horsepower.
Other camshafts in the 204/214 duration and 448/472 lift ranges provide added low-end torque. In addition to upgrading