Does your Jeep’s factory V-8 pack the same punch as a neutered monkey? Missing that certain something? Do you get the feeling your AMC V-8 would rather sit on the couch with a box of bon-bons than get out and tear it up? Whether you’re starting with a pedestrian 304, a smog-laden 360, or even a 401, here are some areas on which you can focus your attention to put the spark back in your engine’s mojo.
Ditching your fixed-blade or even clutch-type mechanical fan can free up some ponies and improve your cooling. On the dyno, it can be as much as 10hp and on the street 1-2 mpg.
Smaller 304s respond well to Edelbrock’s Performer camshaft (PN 2132). If you’re building a 360, Summit Racing’s PN SUM-8600, or Comp Cam’s XE256H or XE262H camshaft work well. Or, larger AMC 401s have the cubes to tame a Summit SUM-8601 or even Edelbrock PN 7132. Figure anywhere from 10-40hp depending on cam and engine.
Whether older points-type or newer Motorcraft electronic, your zapped stock ignition can potentially be costing you up to 25hp. Performance Distributors’ DUI HEI distributor or its cool new Jeep Duraspark ignition system will really up the power and mileage. Other good upgrades are available from Accel, MSD, Pertronix, and Mallory.
The factory snorkel-type filter assembly is fine for stock engines, but with power adders comes the need for more airflow. An open-element air filter with a high-flow filter can free up as much as 5-10hp over the stocker running a paper unit.
Jeep's Autolite 4300 four-barrel is hard to tune and not performance-orientend. You can see 5-15hp with a properly tuned Holley Truck- Avenger, 470 cfm on a 304 and a 670 cfm on the 360 and 401. Or a Junkyard Q-jet is good if you know how to work'em.
Aftermarket or stock manifold, adding a 1/2-1-inch-thick open phenolic carb spacer will help cylinder sharing at low rpm's and will increase upper rpm power by 5-10hp depending on your other components.
Replace your iron two-or-four-barrel boat anchor with a high flowing aftermarket aluminum manifold to add 10-15hp. Edelbrock's Performer RPM never dissapoints.
Stock Amc V-8 manifolds flow okay, but they tend to crack. Replacing them with long-tube headers will help power at all rpms, while shorty headers will see good gains but mostly at higher rpms. Figure 5-15hp and a bunch more torque from this mod.