When you install the oil pickup, make sure the tube and O-ring seal are straight in the oil pump. If not, you can have low oil pressure and damage your new engine. All LS-based engines use an O-ring-style oil pan gasket. As long as it is not damaged, it can be reused. Even some aftermarket pans, like the one from Canton, use the GM O-ring gasket.
Transmission Bolt PatternsAll LS-series engines share a common transmission bolt pattern. It is the same as the traditional Chevy pattern, with one missing bolt. The center bolthole on the passenger side is not drilled or tapped in production blocks because the hole would protrude into the water jacket. This bolt can be left out if you are using a traditional transmission or bellhousing. If you have a LS-based transmission bellhousing, it will not have a hole for a bolt. Some aftermarket blocks and GMPP LSX blocks have this bolthole and if possible it should be utilized.
Flex Plates And FlywheelsThe rear snout on the crankshaft of all LS series engines is 400 thousands short compared to traditional small- or big-block Chevy engines. If you are using a LS engine/transmission package, there is no issue. If you are installing a traditional GM transmission on LS engines, changes must be made to locate the flywheel or flexplate in the correct location. Spacers are available that relocate the flywheel to the traditional location. If you use the spacer, make sure you install a long rollpin into the alignment hole where the flywheel bolts on. This will help prevent the flywheel from coming loose.
Also, always use new bolts or Loctite on used bolts. The better option for high power applications is to use a flywheel or flexplate designed for this application. They are designed to locate components in the correct location. If you use one of these flexplates, a spacer must be installed on the snout of the converter to extend it. This allows the converter to retain the pilot in the end of the crankshaft. Not using this can cause transmission failure.
If you are installing a stick shift transmission, there are two locations in the rear of the crankshaft for pilot bearings. One takes a small bearing, designed to sit deeper in the crank. The other bearing is larger, and sits closer to the transmission. Make sure you measure the input of your transmission and install the correct bearing. Another area or concern is the throw-out bearing. Most people use hydraulic throw-out bearings, but regardless of which style you use, measure the travel to make sure you have enough travel to fully release the clutch.
If you do not have enough travel, the clutch will drag and you will not be able to shift when the engine is running. Also make sure the throw-out bearing is not too close to the clutch. If this happens the clutch cannot fully engage and will slip. Even if you are using production LS components with an aftermarket clutch, this must be checked. This is a critical area, and no one wants to remove the transmission to repair it after installing a new engine.
Accessory Drive SystemsAlmost every vehicle GM builds with a LS engine has a different accessory drive. Most of the car-based systems interchange. Because of availability, the most popular systems used in engine swaps are the Corvette and the "F" car. Another popular system is the CTS V. It tucks in closer to the engine, and works well in limited space applications, like an LS7 Solstice.
There are a number of aftermarket kits available to fit many applications. If you prefer factory components, GM Performance Parts offers a complete CTS V (PN 19155066) and Corvette (PN 19155067) accessory drive kits. They come with every component required, including the bolts. Truck-based accessory drive systems do not work well with car intake manifolds since the throttle body interferes with the alternator bracket.