Combining Multiple-Induction With Modern Fuel Injection
When most of our Mopars were built, a carburetor adorned the intake manifold, handling the mixing of fuel and air and keeping the proper ratio of each under most driving conditions. If your car was an economy model, it came with a one- or two-barrel carburetor; if it was a performance model, it came equipped with a four-barrel, or maybe even multiple carburetors if equipped with a Hemi, special 340 Six-Pack, or 440 Six-Pack engine. Though it has long been debated as to the actual performance gains multiple carburetors can provide, it’s generally accepted that multiple carburetors offer slightly more power in a street-driven application, but at the expense of drivability and reliability. Fuel injection was offered by some manufacturers during the musclecar era, but the fuel-injection systems of the time were crude, prone to vapor lock, and even more untrustworthy than most carburetors.
Though multiple carburetor induction of the ’60s and early ’70s was admittedly somewhat unreliable, the engineers at Chrysler figured out a way to make it better. By using three relatively simple two-barrel carburetors, they could tune the engine for daily driving using the center carb, then actuate the two outboard carbs when maximum power was needed for the best of both worlds. The Chrysler Six-Pack setup was actually very drivable, offered relatively good economy if you kept your foot off the floor, and great power once all six barrels were opened up. Basic Holley two-barrel carbs were used for simplicity, and the outer carbs were vacuum-actuated units that didn’t even have metering blocks for jet changes. While this system improved overall reliability and worked well on a stock engine, if you wanted to modify your engine, having no jets to change in the outer carbs made it difficult to tune the engine once modifications were made. For this reason, many Six-Pack setups were removed once a car was modified and replaced by a single four-barrel.
Regardless of how multiple carburetors actually perform, the appeal of opening the hood at a cruise night and showing off dual four-barrels, or a trio of two-barrels, is enough to negate the drivability and reliability issues of these systems for some enthusiasts.
We admit that an open hood with multiple carbs adorning the engine does turn heads, but can that same look be achieved without sacrificing reliability? Thanks to Bruce Bridges and the team at F&B Performance Engineered Products (F&B), the answer will soon be yes. F&B is-and always has been-a Mopar company. Starting out by modifying and porting 5.2 and 5.9 Magnum throttle bodies for extra performance, F&B has grown their business and now manufactures their own billet throttle bodies for Chrysler applications. F&B throttle bodies are designed to maximize airflow and inlet velocity, while at the same time requiring minimum effort to install. Since their designs have much larger inlet areas than factory throttle bodies, tapered flow paths for maximum ram effect, and are compatible with factory air intake systems, they are a great choice for adding fuel injection to your classic Mopar. Since much of their initial work involved the Mopar 52mm two-barrel throttle bodies, and since a Six-Pack setup works well with carburetors and looks cool, Bruce decided to look into the feasibility of Six-Pack electronic fuel injection.
Adding electronic fuel injection to a classic Mopar is not a walk in the park, but it’s also not as difficult as you may think. Since fuel-injection systems need much higher fuel pressure than carburetors to function properly, the car’s fuel system must be upgraded. Also, a computer must be installed in the car to control the fuel-injection system, and that computer requires information from a variety of additional sensors that must be installed as well. While this may seem too complex for the average enthusiast, it’s really not. F&B has made the task far easier by designing a well thought-out fuel-injection system that includes everything necessary to install a Six-Pack EFI system on your car. Their kits offer quality components and don’t require too many modifications to work properly on your older Mopar. Since gas is more than four bucks a gallon at the time of this writing and not expected to get any cheaper, we think adding EFI to our older cars is a great way to boost economy, while not sacrificing performance.
Combining the reliability of fuel injection with the look and performance of a Six-Pack just makes sense. We decided to follow along as F&B installed their prototype Six-Pack EFI kit on their latest project: a ’72 Plymouth Barracuda. This Barracuda has been in Bruce’s family since his grandmother bought it new and has clocked some 324,000 miles over the years. The engine is a 318 that was rebuilt several years ago with an overbore, new 9:1 hypereutectic pistons, a mild cam, and a little head work.
Seeing how easy it is to install the Six-Pack EFI system certainly convinced us of the viability of this package. With kits soon to be available for the B, RB, LA, and Magnum engines, we wouldn’t be surprised to see more cars at the cruises, shows, and races we attend sporting a Six-Pack of EFI.