Our hobby is at the precipice of a dramatic trend shift that will determine which trucks are being customized regularly from here on out and what mods are being performed. Due to a number of economic factors, a resurgence of older iron (pre-2000) making a comeback in the custom scene is taking place. Fullsize trucks are cheap today and engine swaps are an economical way to inject some new life and modern performance into an older truck. Many of today's hottest swaps aren't the traditional anemic small-block-to-rip-snortin'-big-block affair either. Lots of sport truck owners have learned that double-digit fuel economy is just a fuel-injected engine and electronic overdrive tranny swap away.
One swap that is on fire as of late is the LS1 and 4L60E automatic tranny into GM C10 and C/K series trucks. You can find 300hp 5.3L versions of this fantastic iron block, aluminum-headed engine in the junkyard for a song. It's not unheard of to score the engine, trans, computer, and drive-by-wire pedal assembly for less than $2,000 at a boneyard because thousands of donor Chevy Silverado and GM Sierra pickups came standard with this combo.
Street and Performance has this swap and many others down pat, thanks to its own line of conversion parts and steady supply of engine, transmission, and accessory cores. What got us really excited about this story though is that the company just swapped a brand-new LS3 engine and six-speed automatic trans into a '68 Chevy C10 truck! The thought of 430 horsepower for blasting away from a stoplight and six gears for highway cruising in a standard cab truck really made us drool, so we had to know how it was done.
Follow along with the pictures for an overview of the changes the truck needed, and if you've got more questions or want to order parts then call the shop. Street and Performance has a massive catalog and instructional DVD to help get you started. Check it out!
What's Going Under The Hood?
GM part number 19201992 is the new 430hp LS-3 fuel injected crate engine. It's an all-aluminum 376ci powerhouse with a 6,600 rpm redline that first arrived in the '08 Corvette and is now available through GM Performance Parts dealers. Amazingly, this small-block belts out 424 lb-ft of torque, which for a pushrod V-8 engine of this size is simply stunning. It's the right motivation for a sport truck.
There are a couple of different variations of this transmission, but Street and Performance picked the 6L80E for the Pontiac GTO, which is part number 17803868, because it has a low-profile tranny pan for added ground clearance.
Part One: Engine Transplant Prep
1. After removing the complete...
1. After removing the complete drivetrain and accessories from the truck, the LS-3 is prepped for installation. First, the water pump is drilled and tapped to plumb a steam line from the pump to the cylinder heads. This is done to prevent steam pockets from building up in the cooling passages and causing hot spots to form in the block.
2. Next, S&P conversion mounts...
2. Next, S&P conversion mounts are bolted onto the sides of the aluminum block. Note that like most late-model GM products, everything on this engine is threaded for metric fasteners, which S&P provides with its kits. The LS motor mount location is several inches farther forward on the block than the original small-block engine that this truck came with. The conversion mounts fix this problem.
3. The engine is flipped upside...
3. The engine is flipped upside down on the engine stand so that a Camaro-style oil pan can replace the Corvette-style pan that came on the engine and add clearance in the sump area. S&P provides excellent instructions on its website for torque specs on every fastener.
4. The LS-3 is then flipped...
4. The LS-3 is then flipped right-side-up once again, so that the S&P oil pressure sending until adapter can be installed at the rear of the block. This is adapter has three ports: a 16mm male, 16mm female, and 1/8-inch npt port. The metric ports thread into the block and to a sensor for the computer and the npt port makes it possible to run the factory oil pressure gauge. It's a necessary and trick piece.
Reluctant Recipient Combinations
Not all LS engines are created equal. In fact, it's possible to have two LS1s from different model years that require completely different computers and sensors. Why is that? Well, the rear of the LS crankshaft has a round ring called a reluctor wheel. The reluctor wheel is used by the computer to determine the position of the crankshaft during each combustion cycle. There are two different wheels used by GM. One is a 24-tooth wheel and the other is a 58-tooth wheel. They are easily identified by looking into the passenger side of the engine block through a port located behind the starter. Or you can look at the plug that's hiding this port. If the plug is gray in color, the engine has a 58-tooth wheel and if the plug is black, then the crank has a 24-tooth wheel.
It gets even weirder now. Late-model Cadillac Escalades powered by new LS engines have variable cam timing, which the truck and car engines don't have. So always contact an experienced LS engine swap specialist like Street and Performance before you buy any swap parts, whether they are new or used. Compatibility is a big issue with the latest and greatest high-performance computer-controlled hardware from GM.
Part Two: Droppin' The Bomb
1. Test-fitting the engine...
1. Test-fitting the engine into the C10 engine bay without the transmission or radiator installed. Note that LS2, LS3, LS7, LS9-powered Corvettes have a flat water pump pulley. If your donor engine came from an earlier-model Camaro or Trans Am, it also uses this type of water pump, but the Corvette balancer is 3/4-inch shorter for more radiator and electric fan clearance.
2. The plastic intake manifold...
2. The plastic intake manifold was removed earlier to prevent damage when installing the engine. Here, it's re-installed and the hardware is first torqued to 44 lb-ft and then 89 lb-ft.
Part Three: Accessorize It!
1. It's time to dress up the...
1. It's time to dress up the engine with S&P's polished accessories. This is the company's new water pump cover.
2. And this is the idler bracket...
2. And this is the idler bracket kit, which bolts to the engine block and cylinder heads and is the key to mounting the A/C compressor and alternator.
3. The ignition coil packs...
3. The ignition coil packs are re-installed onto the valve cover brackets now. It's not necessary to remove them prior to installing the engine, but it does add clearance near the back of the head and firewall. Notice that polished bracket bolted to the cylinder head-that's where the A/C compressor will end up.
4. The Sanden 508 compressor...
4. The Sanden 508 compressor has several advantages. First off, it works with the existing A/C system and features rear exit A/C lines for a more direct plumbing route.
5. On the opposite side of...
5. On the opposite side of the engine, S&P adds a chrome-plated factory GM 140-amp alternator, which has enough juice output for a fuel-injected engine and all the accessories in a truck, like the audio system, lighting, electric fuel pump etc.
6a. The serpentine belt isn't...
6a. The serpentine belt isn't pictured, but here you can see where the adjustment comes from. Belt-tension is set via a pair of these threaded rod ends. It's tapped with a right-hand thread on one end, and a left-hand thread on the other end. This makes adjusting the belt tension as easy as turning the shaft with a wrench and then tightening the jam nuts to lock it in place.
7a. This kit features S&P's...
7a. This kit features S&P's mid-length thermal coated headers. The flanges are cut from stainless steel and the 2-1/2 inch primary tubes easily clear the framerails, steering linkage, and starter. If you look closely at the rear of the head you'll see the sending unit for the coolant temperature gauge.