One of the most important steps of your swap is identifying the accessory drive “spacing” you need. This spacing is where the harmonic balancer positions your main drive belt for your accessories. Be aware of these variations that came from the GM factories. They each have a unique accessory drive belt position: LS9, LS4, Corvette, Camaro LS1, and Truck. Another thing to know is that dry and wet oil sump, harmonic balancers are not interchangeable due to the crankshaft length

Bracket Selection

To make this simple our ICT Billet brackets are designed around these three crank pulley spacings which nearly all engines you will ever come in contact with:

• -1 spacing Corvette, CTS-V, G8, SS Sedan
• -2 spacing 1998–2002 Camaro, GTO
• -3 spacing Trucks, SUVs, 2010–2015 Camaro

Once you know your spacing number, the matching bracket will end with that dash number.

Example: 551577-2 fits a Camaro LS1. 551577-3 fits a truck engine with a stock crank pulley.

Corvette engines used -1 spacing due to tight engine bays and high performance needs. The GTO and early Camaros used -2 spacing. Trucks and later Camaros used -3 spacing, which places the accessories furthest forward and allows the alternator to sit in front of the passenger side cylinder head.

For most swaps, -3 spacing is our recommendation. It provides the cleanest engine bay, offers the most bracket options, and avoids excessive pulley overhang. We do not recommend spacings beyond -3, as pushing accessories further forward can reduce balancer effectiveness and cause belt runout.

Supercharged Applications

GM equipped the LSA engine with an 8-rib supercharger pulley while retaining the Corvette 4 and 6 rib accessory drives. This allows an easy swap to an LSA balancer without changing existing accessories.

The LS9 later introduced a unique 6-rib accessory pulley location along with an 11-rib drive for the supercharger, power steering, and water pump.

Changing and Installing Pulleys

Crank pulleys can be interchanged across nearly all wet sump LS engines. For example, we have installed an LS4 balancer on an LS3 using a simple spacer in our twin-turbo Lamborghini build.

Always remove balancers with a proper puller and reinstall using an installer tool. The crank bolt is torque-to-yield and must be replaced every time and to prevent oil leaks from the orange sealing material leaking on the underside of the bolt head.

Wet sump engines use this bolt . Dry sump engines such as LS7, LS9, and some Grand Sport LS3s use a longer bolt. Torque to 37 ft-lbs plus 140 degrees using a balancer holding tool.

Balancer Safety and Recommendations

Harmonic balancers can be dangerous if over sped, overloaded, or damaged during removal. We have seen pulleys come off under load and cause serious damage. We recommend using an SFI rated balancer such as ATI. The ATI balancers allow the use of a HTD drive so you can add a dry sump oil pump or belt driven fuel pump for race applications.