24x Small-Block Chevy Hardware Installation Guide

The LS1 engine has a different firing order than the early small-block Chevy and LT1 engines. Specifically, cylinders 2&3 and 7&4 have been swapped. If you are building your own engine harness, be sure that you swap injectors and coils 2&3 and 7&4 at the PCM. If you have ordered a new engine harness from EFI Connection, the harness has been built in this way. GM also did this for the 2001-2002 Express Van. The Express Van used an early (Vortec) small-block engine, but was operated with the 12200411 (LS1) PCM. For proper Closed Loop operation, bank-to-bank fueling can be corrected through the PCM calibration by assigning the appropriate injector to each bank. The easiest solution is to load a calibration from a 2001-2002 Express Van and then copy/paste the injector to bank assignment table values into your LS-based calibration.

Knock Sensor(s)
The LS1 PCM accepts up to two knock sensors. EFI Connection has been using the 96-97 LT1 Camaro/Firebird knock sensor with 24x conversions on both early Small-Block Chevy and LT1/LT4 conversions. While a knock sensor is not required, it is strongly recommended. Knock sensor settings can be configured/reconfigured within the PCM calibration.

Installing the 24x Crankshaft Reluctor
The crankshaft reluctor simply installs on the snout of the crankshaft and is indexed by the crank timing sprocket key. After final assembly, the reluctor is held firmly in place between the crank timing sprocket and harmonic balancer. The crankshaft reluctor adds about 2.5mm of thickness, causing misalignment of the accessory belt. Be sure to either install a 96-newer Vortec balancer or mill the thickness of the reluctor from your balancer before final installation.

Installing the Vortec Timing Cover
When GM began using the plastic Vortec timing cover, the sealing face of the block was slightly changed. Be sure to test fit the Vortec timing cover to your engine to observe any areas where you will need to generously apply RTV silicone sealant. Engine blocks prior to 1996 WILL seal if sealant is applied correctly. Some have applied JB Weld to the face of the block for an additional sealing surface. JB Weld is not required.

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