12–bolt Housing, 4.10:1 Gears, and McLeod Clutch
The fourth–generation F-body’s glaring weakness is its puny Salisbury–type 10–bolt rear axle that traces roots to the weak–kneed Chevy Monza of the smog ’70s. It’s a miracle that the 7.6–inch ring gear and spindly C–clip axleshafts endured the LS1’s wrath; it lives because the stock tires and/or clutch will slip before the load exceeds the axle’s torque capacity. After fitting 4.10:1 gears, however, it failed three times in 24 passes. A Kenny Thomas Racing Enterprises 12–bolt and clutch–type limited slip differential (sold as a direct bolt–in that reuses the stock disc brakes and ABS) eliminated the weak link. While they were at it, the sons of S.A.M. added bolt–in Competition Engineering subframe connectors, a Random Technologies torque arm, M/T ET Street DOT slicks (26x11.5–16 fitted to the 16x8 Center Line rims, run from 9–15 psi) and a McLeod clutch (12–inch disc, PN 360250) and pressure plate (PN 260873–E). While the chassis dyno failed to show an increase, the increase in torque multiplication and traction knocked a full half–second off the e.t. and scooted the car down the quarter in 12.28 at 112.05 while dropping the 60–foot time to 1.7 seconds.

The beefy KTRE 12–bolt can handle tons of abuse, while rectangular Metco control arms and adjustable Random Technologies torque arm keep tires planted.

Cam Change
Cam grinders have finally begun to produce specific designs for the LS1. Though the stock cam suits the needs of the stock engine and can keep pace with numerous modifications in other areas without halting progress, the LS1 will benefit from more aggressive profiles. A Comp Cams hydraulic roller (224–degree at 0.50, 0.533–inch lift on I and E, 113–degree lobe separation, and 113–degree intake centerline) produced major improvements. With the cam installed straight up, performance in the quarter–mile was 12.12 at 114.80, and wheel power rose to 374 hp with 376 lb–ft. The cam was then advanced 4 degrees, but the engine lost 9 hp and 4 lb–ft. Massingill says, "As a rule of thumb, if advancing a cam helps power, it is a sign the cam might be too large. If you retard the cam and pick up power, the cam is often too small for the motor." Following this assumption, the S.A.M. LS1 has airflow capability that a larger cam may unleash.

A Cloyes Hex-Adjust timing set made especially for the LS1 makes camshaft adjustment possible. Massingill says this engine is a joy to work on because its O–ring gaskets never require scraping and can be reused several times. Unlike most designs, the intake manifold needn’t be removed to change cams. Simply extract the pushrods, roll the cam until each lifter becomes lodged in its composite plastic guide at full lift, then slide camshaft out.