A big reason that the small-block Chevy was so popular with the Bow Tie crowd was because for decades it changed very little, making upgrades and interchangeability easy. The same can be said for the Gen III/IV LS engines, as the basic architecture has remained the same for nearly 20 years. While the LS family of engines has evolved, that celebrated thread of ancestral interchangeability has remained. But change is inevitable.
The time-honored approach of bolting older LS truck engines into classic muscle cars is often accompanied with updates to the engine. In our case, we bought a 1998 iron 6.0L engine and decided that upgrading it with a previously owned LS7, or perhaps the affordable LS9, cam would be an easy swap. It is—if you know the details.
While bolting a cam into an LS engine is a simple routine, there are a couple of essential details that require attention. The original Gen III car and truck LS engines placed the cam sensor at the back of the block reading the 1x trigger located on the camshaft that was compatible with the stock 24x crank reluctor. With the evolution of the Gen IV LS2 in 2005, one change relocated the cam sensor to the timing chain cover. The cam gear also doubled as the cam sensor trigger wheel remaining a 1x for 2005. That evolved in 2006 when GM switched to a 58x crank reluctor, which demanded a 4x trigger for more resolution. Not all passenger car engines followed Corvette’s lead, however. For example, the 2006 GTO LS2 engines retained the original 24x crank reluctor and its 1x cam sensor partner.
None of this would be all that important were it not for the time-honored performance pastime of cam swapping. Using our early iron block 6.0L truck engine as an example, the supercharged LS9 camshaft makes an affordable upgrade with a new one priced at less than $130 from popular mail-order outlets. The LS9 is a Gen IV three-bolt cam, so it does not have a 1x cam sensor trigger near the back journal like a Gen III cam. To accommodate the LS9 cam in an earlier Gen III engine like ours requires a front-mounted LS2 timing cover with its front-mounted sensor and the correct cam gear.
Depending upon the engine and the computer you are using, you might also need a cam sensor wiring harness extension that will connect the stock wiring harness to the relocated cam position. We found an extension/adapter harness from Racetronix for a mere $19. Plus, they make one that plugs directly into the LS2 sensor (PN LS2-CSAH) so you don’t need the short extension harness located on the timing chain cover—unless your sensor already has one—which then uses the PN LS2-CSAH-2 harness.
There are other related conversions (like replacing a single-bolt cam in a 2007-newer LS3 with a three-bolt performance cam), but this story will focus on swapping in an LS7 or LS9 three-bolt cam into an iron-block 6.0L engine. We found most of the parts we needed at Summit Racing for a really great price. In fact, if you choose to retain the lower cam gear and forgo the short cam sensor harness, the hard parts come to roughly $120, not counting the cam.
So if you have considered updating your older LS engine but have held back because you weren’t sure of what you had to do, you can see that this conversion is a bolt-in R&R—which stands for Replace & Race!
The original Gen III LS engines placed the cam sensor at the rear of the engine, while 2005 LS2 and later Gen IV engines moved the cam sensor to the front of the engine. All you have to do to update is add a new front cover, sensor, the appropriate cam drive gear, and a sensor extension harness.
This cam drive gear layout tells the story. Gear A is the original LS1 three-bolt Gen III gear with a smooth face. Gear B is the 2005-’06 GTO three-bolt, 1x cam trigger for 24x reluctor engines. Gear C is a three-bolt 2006-and-later LS2 with 4x cam sensor triggers for 58x engines. Gear D is a single-bolt 4x gear for Gen IV 2007-’14 58x LS2 and LS3 engines. Except for Gear A, these are all Comp Cams gears.
The parts we ordered from Summit Racing to convert to an LS2 front-mounted cam sensor included the timing cover, the cam sensor and wiring harness adapter, and the appropriate cam gear. In this case we need a three-bolt, 1x gear since our engine is still a 24x crank sensor engine.
Removing an LS damper requires an LS-specific tool. We found this kit at Summit Racing. Remove the damper bolt and place the appropriate length pin into the crank bolt hole. The puller then presses against the pins to remove the damper. Installing is easy using the tool in the foreground.
The hardest part of this swap is removing the balancer. We used Summit’s combo puller and installer kit. There were no instructions so it took us a few minutes to figure it out. The small pins fit down inside the crank snout.
Remember to remove the two pan bolts that come up from the bottom when removing the timing cover. As you can see, our 6.0L is a true survivor and pretty nasty on the inside. Position the cam gear dot at the very bottom and then you can remove the cam gear and replace it without having to remove the oil pump. This engine really needed a new chain too, as it was stupid loose.
Note that we added a Comp Hex-A-Just timing set to this engine so we could degree the cam. We removed the oil pump to replace the bottom gear, which necessitated aligning the oil pump gears over the crank. The easiest way is to leave the oil pump mounting bolts slightly loose and rotate the engine through three or four revolutions. This will align the pump gears. Torque the oil pump bolts to spec and you’re ready to install the cover.
We made a front cover alignment tool out of an old LS truck balancer by opening up the hub’s I.D. with a flapper wheel until it easily fit over the crank snout. We installed the cover loosely and slid the hub into the cover. The seal will position itself around the hub. When the seal is concentric around the hub, tighten all the cover bolts including the two that come in from the bottom and then remove the alignment tool.
Here’s the LS2 timing cover installed. All that’s left to do is press on the balancer and connect the cam sensor harness and you’re ready to rock.
|Description||Summit Racing Part Number|
|Summit LS2 cover, sensor, & ext. kit||NAL-12633906|
|Dorman LS2 cover||RNB-635-515|
|ACDelco LS2 cam sensor||ADO-213-3826|
|Dorman cam sensor harness pigtail||RNB-645-526|
|Cloyes LS2 cam gear||CLO-S878T|
|Sealed Power chain||SLP-222-4194|
|Melling crank sprocket||MEL-S827|
|Comp timing set 1X, 3-bolt (Gear B)||CCA-3158KT|
|Comp timing set 4X, 3-bolt (Gear C)||CCA-3172KT|
|Comp timing set 4X, 1-bolt (Gear D)||CCA-7107|
|Summit LS balancer puller/installer||SME-K-906008|
|Summit installer only||SUM-900135|
|Racetronix Part Number|
|Racetronix extension adapter harness||LS2-CSAH|
|Racetronix extension adapter harness||LS2-CSAH-2|
|This list includes multiple PN applications for individual parts you may find necessary. Not all of these parts are necessary for the conversion we covered in the story.|