The Right Induction
When we embarked upon this swap, we faced a lot of choices. For example, we considered two induction systems: Holley/Weiand and Edelbrock/Mustangs Plus. Holley provided us with a Weiand Action Plus intake manifold with a 600-cfm four-barrel carburetor. Mustangs Plus set us up with a polished Edelbrock Performer 289. When our project manager, John Da Luz of JMC Motorsports, examined the choices, he had to consider the engine and how it would be driven. John stressed that bigger isn't always better, especially for street applications that rely on a small-block Ford for the commute or weekend cruising. Crisp off-idle response is what we want.
The Edelbrock Performer 289...
The Edelbrock Performer 289 low-riser provides the right-size plenum and port sizing for our application. According to John of JMC Motorsports, had we built a 302, the Weiand Action Plus would have gotten the nod because we would flow more air.
This is the Weiand Action...
This is the Weiand Action Plus low-rise manifold. Note the slightly larger plenum and ports which are more appropriate for a 302, although it will work fine on a 289. The key to proper selection is when you want torque to happen. John knew the Performer 289 low-rise would make torque earlier on a 289.
If you're going to spin your...
If you're going to spin your small-block high or huff a lot of displacement with a 331 or 347, the Edelbrock Performer RPM is a better choice. The Performer RPM, as well as Weiand's Stealth, is a dual-plane manifold more bent on high rpm use. These manifolds perform well in daily driving, and when you pin the butterflies, they deliver greater sums of torque at high revs.
Because Trans Am Racing built the 289 with a mild flat-tappet Isky camshaft on the order of 250-280 hp, John knew we needed to keep manifold and carburetor selection modest. The Edelbrock Performer 289 and Weiand Action Plus manifolds serve basically the same purpose: terrific low-end torque for street use. Both manifolds begin making torque around 1,500 rpm. The tie-breaker was port and plenum size.
In this case, we went for less instead of more in terms of manifold and carburetor size. The Edelbrock Performer 289, with its slightly smaller plenum and intake ports, made it more appropriate for our mild street 289, but there's nothing wrong with Weiand's Action Plus. It's also an outstanding manifold for cruising and freeway acceleration. We just needed something a pinch smaller, which is exactly what we found in the Performer 289 low-riser.
Although we opted for a 600-cfm Holley, our 289 would get along fine with a 500-cfm four-barrel carburetor, which would also deliver adequate low-end torque along with acceptable fuel economy for a carbureted V-8.