LS Engine Pulleys - LS Accessory-Drive Swap Guide

This shows the depth difference... 

   

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This shows the depth difference between a truck balancer on the left and a Camaro/Firebird balancer on the right.

Harmonic Balancer Depths
The following chart lists the dimensions of the three different pulley depths used on the Corvette, Camaro/Firebird, and truck accessory drives. We've listed two different ways of measuring these, both with the balancer on the engine and on the bench. The depth of balancer dimension is measured from the rear of the balancer hub to the leading edge of the balancer/pulley (overall depth), which can be used to identify a balancer not mounted on an engine. We also included the depth from the front cover to the front of the balancer if it is installed on the engine.

Kunkel sent us this photo... 

   

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Kunkel sent us this photo of an F-car accessory drive on his iron 6.0L engine. Because his Hooker engine mounting plates move the engine back farther than most to fit the LS1 swap headers, he had to notch the crossmember to fit the alternator. He has already reinforced and filled in this notch to make it stronger and look better. With most engine mounts, the F-car drive alternator clears the stock subframe.

What Fits--And What Doesn't!
The main focus of this story is to give you an idea of which factory-available accessory drives can be used for engine swaps. But just as important is which factory configurations don't fit. The difficulty with generic information like this is it all has to be qualified with a bold-faced "it depends" because of the multiple fore/aft locations for LS engines in muscle car chassis. Not all engine conversion mounts place the engine in the same location, so be aware of this major variable. For example, the Street & Performance, ATS, and Morrison mounts (and probably others) locate the engine in the same position, but the Hooker mounts (for early Camaros and '68 to '72 Novas as an example) locate the engine roughly an inch farther aft. The BRP mounts raise the engine up and also push it much farther forward. In the interest of available space, we'll save these details for a later story. In this sidebar, we deal mainly with Gen III/IV alternator and power steering packages. As for the factory A/C pumps, in most cases the factory A/C compressor will not clear the chassis without notching the engine crossmember.

The '64 to '72 GM A-body cars include Chevelle/Malibu, Pontiac Tempest/Le Mans/GTO, Buick Skylark/GS, Olds Cutlass/F-85, and since the early '70 to '72 Chevy Monte Carlos are based on an A-body chassis, these cars should also be similar to Chevelle fitment details. For all these cars, the factory Corvette accessory drive will clear all suspension and steering components. The downside is that this system tends to be hard to find and expensive. Camaro-based accessory drives don't fit Chevelles because the alternator crashes into the steering box. The truck drives will work if modified with a 5-inch-diameter power steering pump pulley to clear the steering box, but most car crafters shy away from this system for aesthetic reasons, since the alternator sits very high.

For early '67 to '69 Camaros/Firebirds and '68 to '74 Novas with a factory front subframe, either the F-car LS1-style or the Corvette drives will fit, although the F-car alternator is snug. If you're using the Hooker mount kit, you will have to notch the engine crossmember to clear the alternator. The truck accessory drives are way too tall to clear the low hood line while, again, the Corvette accessory drive will bolt right on if you're fortunate enough to own one of these systems.

The most important change for the second-generation ('70 to '81) Camaro/Firebird is that these cars converted to front steer, moving the steering box in front of the axle centerline like a Chevelle. This makes fitting the F-car LS1 accessory drive, with its low alternator, tight. It will clear the steering box, but clearance is minimal depending on which engine mounts are used. The Corvette-style drive will clear everything, while the truck system will not fit under the stock hood line. As with the other body styles, the A/C will only work if it is relocated up high on the passenger side.

We mocked up an iron 6.0L...        read full caption We mocked up an iron 6.0L engine using Scoggin-Dickey engine mounts and a truck accessory drive on a '66 Chevelle and found that a 6-inch power steering pulley hits the power steering box. This can be rectified with a smaller, GM 5-inch-diameter pulley (PN 10166335). This smaller pulley has a 0.750-inch shaft diameter.

CC reader Troy Matos sent...        read full caption CC reader Troy Matos sent us this photo of an '04 LQ4 6.0L engine in his '65 Chevelle. Since his car has manual steering, he opted for a passenger-side alternator conversion he found online by referencing "Smokinhawk" at LS1tech.com.

We've discovered that the...        read full caption We've discovered that the F-car and truck alternators are interchangeable, meaning you can probably find a less expensive alternator from a truck compared with purchasing one for a Camaro. These alternators will not interchange with a Corvette system because the mounting lug spacing is different--of course.