Buying a crate drivetrain package off the showroom floor and slipping it between the framerails of your hot rod in an afternoon with the result being a 300hp, dead-reliable, factory-proven combination is something most hot rodders would have a very hard time scoffing at. Getting that same result by way of the local salvage yard via a wrecked Camaro or Chevy truck is even more inspiring. But that's exactly what one can expect with GM's Gen III LS1 engine packages. Available in a number of configurations, one of the most common is that of the 5.7L (345ci) throttle body injected version mated to a 4L60E commonly found in Corvettes and Camaros. Yet while the availability, reliability, and performance of the Gen III family of small block Chevy engines is arguably the best combination ever developed, to say that it is the simplest would be doing a huge disservice to the hot rodding community in general.
Like most modern, fuel-injected engines, the LS1 has a number of items that make it starkly different than other powerplants like it in the past. One of the most obvious at first glance is the plastic intake and individual coils on the valve covers. That plastic intake manifold is actually made with injected nylon with a wall thickness of 3 millimeters. With its low height, light weight, and high flowing characteristics, the intake itself is quite a marvel when compared to previous designs. Entering through the front-mounted throttle body, the air passes through rather long runners before mixing with the incoming fuel charge via the injectors mounted almost directly over the valves. The individual coils are a result of the LS1 family's designed lack of a classic distributor. Instead, it uses a powertrain control module (PCM) that tells the coils when to fire each individual plug using input from the crankshaft position sensor and the camshaft position sensor. While this system is extremely effective in both providing performance and reliability, the resulting wiring harness rivals Medusa's snake-pitted head with its myriad of connectors that run to numerous sensors and pigtail connections. This makes pulling and installing a donor motor from the junkyard and into your classic a fairly complex ordeal if one's not very savvy at either automotive electronics or computer-controlled engine systems.
Here's our LS1 engine in its...
Here's our LS1 engine in its relatively stock guise. Note the coil packs, fuel rails and injectors and the molded nylon intake manifold. Not the prettiest small block that Chevy made.
But where there's a will there's a way and, in the aftermarket industry, that way is oftentimes a company that steps up and builds a kit that makes certain aspects much easier and user friendly. For this particular project, that company is Edelbrock. Teamed up with MSD Ignition, Edelbrock has developed a carbureted system that replaces the intake, throttle body, and injectors with a traditional intake manifold and carburetor along with an ignition controller that plugs into the existing sensors and replaces the factory harness.
What this translates to is a system that completely rids the end user of the worry about making all the factory OEM widgets work together. Pulling an LS1 motor out of a wrecked vehicle can now be done in a manner similar to the way it's been done for 70 years. No longer does every relay, fuse, and module need to come out with the engine, along with the rat's nest of a wiring harness. Simply clip the wires at each sensor and toss the harness aside, saving countless hours spent on the garage floor trying to make sense of a filthy wiring harness from the junkyard. Not to mention the money saved by not needing to purchase the stock PCM or fuel injection components with the engine. Of course there are a few things needed in addition to the Edelbrock kit. Most notably, if you're running a computer-controlled transmission like the 4L60E, you're going to need a remote throttle position control sensor for the transmission's control unit. This attaches to the carburetor similar to a typical kickdown cable. The high-pressure fuel pump will also need to be replaced with a pump setup for natural aspiration use.
At first glance, you'll notice...
At first glance, you'll notice how similar Edelbrock's Gen III carburetor kit looks compared to standard four barrel intake/carb setups of the early Gen I variety. The dual-plane Performer RPM intake and carb combo provide a broad torque curve from 1,500-6,500 rpm. Since the Gen III engines don't feature a boss for a mechanical fuel pump, a 6.5psi, 120gph electric unit will provide the fuel to the engine.
Individual port O-ring seals...
Individual port O-ring seals are one major improvement over the classic Gen I and II intake gaskets. Note the port design unique to the Gen III series of engines.
With the carbureted intake...
With the carbureted intake manifold on the engine, it's easy to overlook the valve covers and headers and mistake the engine as a Gen II.
The MSD 6LS Timing Control...
The MSD 6LS Timing Control Module replaces the stock EFI hardware and allows the user to map a timing advance curve using Pro-Data+ software and fits with matching factory connections for a direct fit installation. Other features include a two-step rev limiter, a vacuum advance curve for cruising economy, and a step retard for use with Nitrous.
When the stock EFI components...
When the stock EFI components were removed, with it went a couple of items that we need to replace. One of those is the TPS, or throttle position sensor. The original unit attached to the throttle body and sent the throttle position information to the engine ECU as well as to the 4L60E transmission's TCI electronic control unit. For our carbureted system, we'll be using this TCI remote TPS that will give the TCI trans control unit the information that it needs to control the electronic transmission.
The Edelbrock intake attaches...
The Edelbrock intake attaches to the heads using ten 6mm x 50mm hex bolts. Intake bolts are torqued in a rotational sequence starting at the center to 11 lb-ft.
An 1/8-inch NPT to 1/4-inch...
An 1/8-inch NPT to 1/4-inch hose fitting installs below the carb base. This will attach to the manifold absolute pressure sensor or MAP sensor after the carb is installed.
Handling the fuel delivery...
Handling the fuel delivery duties is an Edelbrock Thunder Series 650cfm (#1806) carb.
The Edelbrock intake manifold...
The Edelbrock intake manifold has provisions for the LS1 timing control module to bolt directly to it, easing installation. The timing control module's harness is designed as a plug-and-play unit with corresponding connectors for the crankshaft position sensor and the MAP sensor. This is one of the other items that went with the original EFI components that needs to be replaced. This attaches to the rear carb stub and a 1/4-inch hose connects the sensor to the fitting below the carb.
The kit installs just like any other intake/carb setup would on a classic small block Chevy, except for things like the O-ring intake seals that remind you you're working with a contemporary motor. The MSD Timing Control Module mounts onto the intake directly and is comes with a harness that hooks up directly to the sensors and coil packs. A couple of single connections for ignition power, A/C idle compensator, and tach output, and you're off and running.
We followed along recently with the install of the carbureted kit on our LS1-powered 2004 Road Tour car when it returned to Hot Rods & Custom Stuff to receive the conversion. We started in the morning by removing all the offending OEM parts and by that afternoon, we had the coil covers installed and the motor was looking a lot more like a classic hot rod mill. The resulting setup is something any guy could install in a day in the garage, but more importantly, it's much simpler and the induction system can now be tuned with a screwdriver and a jet change rather than by pulling at random lines on a chart using a laptop computer.
...the crankshaft position...
...the crankshaft position sensor...
...the crankshaft position...
...the crankshaft position sensor...
...and the MAP sensor. This...
...and the MAP sensor. This is one of the other items that went with the original EFI components that needs to be replaced. This attaches to the rear carb stub and a 1/4-inch hose connects the sensor to the fitting below the carb.
Here, the harness is attached...
Here, the harness is attached to each respective sensor. The connector on the valve cover will attach to the coil pack harness for cylinders 2-4-6-8...
...while the driver-side coil...
...while the driver-side coil pack harness (cylinders 1-3-5-7) will mate to the connector located on the opposite valve cover. The blue wire is used when the vehicle is equipped with an A/C system, as is ours. This side connects to an Edelbrock Idle Compensator...
...while the blue wire that's...
...while the blue wire that's grouped with the other three non-terminating wires connects to the A/C compressor. This provides timing advance when idle is increased while the A/C compressor is running. The pink wire is the main power feed and should be run to a 12v "start" or "on" switched ignition source. The black wire connects to a good chassis ground and the yellow wire carries the tachometer output signal.
MSD Ignition Multiple Spark...
MSD Ignition Multiple Spark Coils provide increased spark energy and voltage over the stock units along with multiple spark capabilities.
The business end of the TCI...
The business end of the TCI remote TPS hooks up to the carb linkage similar to a throttle kick-down cable.
A Lokar throttle cable mates...
A Lokar throttle cable mates the carb linkage to the throttle pedal inside the passenger compartment.
The Edelbrock electric fuel...
The Edelbrock electric fuel pump was mounted horizontally on the rear crossmember, as close to the fuel tank as possible. A 3/8-inch line was then run from the tank to the pump and from the pump forward to the carb.
The MSD Timing Control Module...
The MSD Timing Control Module is supplied with six modules that plug into the side of the housing that are pre-programmed with various timing curves.
Timing curves from the Mo...
Timing curves from the Module
Edelbrock coil covers are...
Edelbrock coil covers are designed to eliminate the stock mounting brackets on transplanted LS1 engines by fitting the coils directly to the underside of the cover itself.
With the induction system...
With the induction system installed as well as the coils, coil covers, and spark plug wires, it's very easy for the untrained eye to mistake the Gen III engine for that of its predecessors.