MSD Ignition LS1 LS6 Timing & Rev Control - Build An Ignition Curve

This little box is an extremely powerful controller for any retrofit carbureted Gen III/IV engine swap.

'The new darling of the engine-swap set is the GM Gen III family of small-blocks that includes everything from the lowly 5.3L truck engine to the LQ9 6.0L all the way up to the swarthy Corvette LS7 427. But not everyone demands EFI sizzle with his Gen III steak. Capitalizing on that concept is the amazingly simple MSD Ignition conversion box that allows you to stick a carburetor on an LS1 or LS2 while still employing the very accurate GM distributorless ignition system (DIS). We've rubbed our greasy paws over this system several times, and it is so incredibly easy to use that there's no excuse for even considering adding a cumbersome distributor to the Gen III/IV engines. You don't even need a laptop computer if you don't want to get into that. If you can fog a mirror, you can plug in one of these boxes and supply accurate spark to any Gen III/IV engine. We'll run it down, and you can decide if it's cool.

The Background On DIS
Any good race-engine builder will tell you that a distributor is not the best way to accurately assign spark timing to a multicylinder engine. A computer triggering a coil per cylinder is far more accurate, which is what GM did with its Gen III-and-later engines. This type of electronic spark requires a few additional sensors, including a crank sensor to tell the box when the No. 1 cylinder has arrived at top dead center (TDC) and a cam sensor that tells the box when the No. 1 cylinder is on its firing stroke (remember that a piston on a four-cycle engine passes through TDC twice).

The GM Weatherpak connector that plugs into each of the two coil packs mounted on the valve covers. All you have to remember is that the 1-3-5-7 connector goes to the driver-side coil pack and the 2-4-6-8 connector is for the passenger-side coil pack. The MSD harness even has a tag to help you.

This is the cam-sensor location on the early Gen III engines, where the distributor once resided on the small-block Chevy. On the Gen IV engines, this sensor moved to the front of the engine. The crank sensor is located on the passenger side of the block just above the starter motor.

In order to create a vacuum-advance curve, the MSD box requires a manifold absolute pressure (MAP) sensor. If you are building a supercharged engine with high boost, you will need a two-bar sensor for up to 15 psi of inlet pressure.

For those car crafters who would rather run a carburetor on a Gen III/IV engine, MSD created the original LS1/LS6 timing control box. Later, when GM upgraded the Gen IV engines by converting its original 24x crank-trigger wheel to a 58x, it required a new box, which MSD calls the 6LS-2 controller. Both of these boxes do essentially the same thing, creating finite control over the spark advance, vacuum or boost retard, multiple rev limiters, and even custom advance curve, all with a few minor keystrokes. Or, for those who have never overcome their fear of computers, the MSD boxes also come with six different plug-in chips, each with its own basic timing curve. On this level, the MSD conversion box is plug 'n' play at its finest.

The Hookup
OK, if this works so slick, it must take a computer science major to hook it up, right? Well, if a mere eight connections scare you (10 if you want the two-step and nitrous-retard features), perhaps that might be true. But this is really easy. Five of the connections consist of GM-style Weatherpak connectors with two that plug into each of the two coil packs, a three-pin connector to the cam sensor, another three-pin to the crank sensor, and the last Weatherpak connection to a manifold absolute pressure (MAP) sensor. Each connector is designed to plug into only its intended sensor so that they're goof-proof. The last three wires consist of a ground, a switched 12-volt power lead, and a tach lead. Hook those up, and the installation is complete except for mounting the box. Then just plug a basic timing-curve module into the side of the box and you are done. The only way this will get any easier is if somebody does it for you.