1970 Chevelle SS LS6 & Drivetrain - Modern Muscle, Part 2

Part 2: Making the "new" LS6 Fit

Barry Kluczyk Sep 1, 2003 0 Comment(s)
Sucp_0309_08_z 1970_chevelle_ss_ls6_drivetrain Electric_fan 1/19

As is specified in GM's "LS1 Engine Kit Installation Guide" (GM PN 88959384), an electric fan setup from a GM U-van (Venture, Montana, etc.) was mounted to a stock-type radiator.

* The engine is an '03 LS6, but the oil pan is from a Camaro. Over-the-counter LS1 engine kits come with Camaro-style pans, although Corvette and truck pans are available, too. (A truck pan was tested for this swap first, but was determined to be too deep.)
* The cast-aluminum Camaro oil pan was trimmed in the front to clear the Chevelle's crossmember. (Any competent welding shop can perform this modification on similar projects, says Benson.)
* Windage tray was modified slightly to work with the modified oil pan.
* Scratch-built engine mounts.
* Corvette accessories were replaced with '02 Camaro accessories.
* JBA Camaro headers flow into '00 Camaro catalytic converters.
* Standard Chevelle radiator fitted with GM U-van (Venture/Montana, etc.) electric fans and controller.
* Custom motor mounts and frame notched slightly on driver and passenger sides for clearance.
* Custom air intake utilizes '96 Impala SS air box.

Sucp_0309_09_z 1970_chevelle_ss_ls6_drivetrain Alternator 2/19

Despite the A-body's abundant underhood room, there were still some tight fits during the engine swap. Here, the LS6's low-mounted alternator is precariously close to the later-model, tighter-ratio Monte Carlo SS steering box that was used instead of the stock unit. It was an equally close fit between the driver side valve cover and the brake booster. The car is not equipped with air conditioning.

The Chevelle's firewall was left untouched during the swap, although the proximity of the driver side valve cover to the brake booster is very close. "This car doesn't have air conditioning and that made the job infinitely easier," says Benson. "I think an A/C system would have caused us fits in the long run."

Minding the LS6's operation is an off-the-shelf GM computer that is part of a GM swap kit for '99-and-later engines. The controller uses an S-truck mounting bracket, mounted to the driver side inner fender. A base Corvette calibration keeps the engine turning.

Benson points to a few other neat details that give this post-modern musclecar additional underhood character: "To mimic the fuel line routing of the original big-block, we flipped the LS6's fuel rail 180 degrees, so the fuel line flows down the passenger side of the engine," he says. "Also, we used 1970-style hose clamps for the radiator and heater hoses."

Because the LS6 uses a returnless fuel system, a return line from the engine to the fuel tank was unnecessary. However, fuel requirements mandated the use of a high-pressure, in-tank fuel pump. Rather than modify the stock tank, a new tank was crafted with all the necessary inner baffles by Rock Valley Antiques of Stillman Valley, Illinois. As it is painted Restoration Black, like the rest of the chassis, the tank is a hidden deviation from the car's stock appearance.

Sucp_0309_10_z 1970_chevelle_ss_ls6_drivetrain Transmission 3/19

Here, the 4L65E transmission is bolted up. Installing it without resorting to cutting the trans tunnel required the use of 1/4-inch shims placed in the body-mount locations. Raising the car this way avoided the need to bang on the tunnel to fit the transmission. Note, too, the Camaro catalytic converters... This Rally Red Chevelle has a "green" streak.

Along with the tank and high-pressure pump, the fuel system required the use of a C5 Corvette's integral fuel filter/pressure regulator. Although it looks like a standard fuel filter, the device also incorporates the fuel system's pressure regulator, maintaining 58 psi. The filter/regulator has a return line to the tank, but only one high-pressure line to the engine. It's a must for this swap.

Shim Sham
The most challenging part of the swap, according to Benson, was the installation of the 4L65E transmission. Although not much bigger than the Turbo 400, the 4L65E is bulkier in exactly the wrong places to fit the A-body trans tunnel. The solution was a series of 1/4-inch shim, or, as Benson calls them, "pucks." The shims were added to the body mount locations and provided the necessary clearance for the new transmission.

"Without the pucks, we would have needed to hack the trans tunnel," says Benson. "Lifting the body a 1/4-inch is imperceptible to the eye, but it saved all kinds of time and trouble when it came to fitting the transmission."

Also, the tail length of the 4L65E is longer than the Turbo 400's, which required a shorter driveshaft. A 3-inch-diameter aluminum shaft was custom-made for the Chevelle by Sterling Performance Products, of Roseville, Michigan, and was capped with heavy-duty 1350 U-joints. The stock 12-bolt Posi and its 3.31 gears are still in place, although like the rest of the chassis components, the entire rear axle assembly was reconditioned.

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