Now that the LS has burrowed deeply into just about every facet of Chevrolet performance, making power means spinning wrenches and swapping parts. That’s where the power theory runs right into specific knowledge requirements. While the LS is considered a branch of the small-block Chevy’s factory tree, it’s at best a distant cousin with its own, sometimes quirky, set of demands.
We’ve been wrenching on LS engines long enough to have collected some working knowledge that is worth passing along. Some of these technical tidbits you may have seen before if you are an LS veteran, but remember that not everybody has your depth of knowledge. We’ve also run across a couple of new tools that will make your wrenching life easier and less stressful. So with that said, walk out to the garage, open your tool drawer, and get wrenching on that new LS project.
Pre-Lube the Oil Pump
If you’ve removed or replaced the oil pump in your LS, or if the engine is brand-new, it can be challenging to make oil pressure just by spinning the engine with the starter motor. We learned a trick from George Richmond at Melling (the oil pump gurus) on how to pre-lube the oil pump, and it works on all LS engines. Remove the oil passage plug at the front of the driver side of the engine block. This plug is large enough to allow you to shove a 3/8-inch rubber hose into the hole. Then use a small funnel to pour a few ounces of engine oil directly into this passage. This pre-fills and primes the oil pump. This is usually enough to allow you to remove all the spark plugs and spin the engine with the starter motor and make oil pressure to lube the main and rod bearings before starting the engine. If this does not work then you can resort to pressure lubing.
Don’t Drop ’Em
LS engines can be easy to work on. They can also be a pain. The plastic hydraulic lifter holders do a great job of holding the lifters in place so you can change the cam. GM did this because you have to remove the heads to remove or replace the lifters. However, problems can surface with high-mileage engines with plastic lifter holders that become brittle. The trick is to spin the cam around to push up the lifters (after removing the pushrods) and the holders should do their job. But if one or two lifters slip out after you removed the cam, you will hear that awful clink when a lifter drops into the crankcase.
A very creative LS engine builder came up with the idea of slipping a length of 5/16-inch aluminum dowel through each lifter bank. Some guys have used wooden dowels, but we prefer aluminum so there’s no danger of the tool breaking off when attempting to remove it. The dowel may allow the lifter to drop slightly but it’s relatively easy to use a long tool to push them back up. The good news is the lifter won’t drop completely out of the plastic holder. Powerhouse sells this two-dowel set (PN POW101046) or you could easily make your own. We’ve also seen steel rod used. Either way, taper the leading edge of the tool so it’s easier to install and remove.
Seal the Deal
Unlike its small-block cousin, the LS family of engines do not use dowel pins to locate the front and rear covers. GM recommends using ridiculously expensive dedicated tools, but the aftermarket has come up with a much simpler and less expensive idea. Mr. Gasket recently released several tools that make installing both the front and rear covers on Gen III and IV engines much easier. They offer two different front cover seal tools. The LSTC1 aligns the bare cover on the engine over the crank snout after lightly positioning the bolts to hold the cover in place. Then, reverse the tool to drive the new seal into place. The bolts can then be fully torqued. We found we had to also loosen the oil pan bolts slightly to make it all come together.
The other front cover seal tool (LSTC2) is used to properly position the front cover over the crank snout if the seal is already in place.
The rear cover seal tool (LSRC1) positions the cover over the end of the crankshaft, the bolts can be lightly tightened, and then the seal can be driven into the cover.
If you don’t build enough LS engines or perform weekly cam swaps, then purchasing a front seal tool may seem like an extravagance. Before Mr. Gasket introduced these tools, Kenny Duttweiler of Duttweiler Performance suggested that we build our own front cover alignment tool. We dug up an old truck harmonic balancer and used a cutoff wheel to remove the crank hub from the balancer. Then we used an abrasive flapper wheel to lightly hone the hub’s inside diameter until it would slide easily over an LS crank snout. With a new seal installed in the front cover, we placed the cover on the engine; lightly installed all the front cover bolts (including the lower pan bolts); and then slid our lubed, homemade hub into the front seal. After we made sure everything aligned properly, we tightened the front cover bolts and the two vertical oil pan bolts.
One other trick is to place a small dollop of RTV at the corners where the front and rear covers contact the oil pan. This will prevent minor oil leaks where the cover gaskets meet the oil pan gasket.
Be careful—this could happen to you! We ran into this while swapping heads on a 6.0L. We had installed a set of ARP head studs in the engine in anticipation of supercharger boost. As we were applying the final torque sequence on the head studs, something felt as if it was giving way—almost as if the stud was stretching since the torque, which normally increases as we tightened the torque wrench, seemed to flatten out. That’s when we noticed the washer under the nut was turning as we tightened the head stud nut. If you feel this, immediately stop turning the nut or head bolt.
ARP had told us about this a few weeks before. It seems in the process of improving the finish on their washers and bolts, the washer has become smooth enough that it no longer remains in place but begins to spin. This is most often experienced on LS engines because the spot finish on the heads is very smooth, but ARP has seen this happen on Ford Mod engines, especially on the Coyote (not that you care!).
Here’s why this is a big problem. Roughly 50 percent of the torque required to create a clamp load on the head gasket is absorbed by friction between the underneath side of the bolt head and the washer—or in the case of a head stud, between the nut and the washer.
Another roughly 30 percent of the torque is absorbed as friction between the threads and the block on a bolt or between the threads and the nut with studs. This leaves approximately 15-20 percent of the applied torque that actually stretches the bolt. But if the head bolt washer turns, it essentially becomes a bearing that dramatically reduces the friction, allowing more torque to be applied directly to the bolt. This can quickly damage the bolt by stretching it beyond its yield point. If that happens, the bolt is damaged and must be replaced. The other possibility is that the threads will pull out of the block. Either situation is bad.
ARP showed us a simple trick to avoid this problem. Simply sand the head side of the washer with 60-grit sandpaper, making about three passes across the washer. This creates a rough enough surface so the washer does not move. Once all the washers are sanded, be sure to clean them thoroughly. It’s also important to use ARP’s Ultra-Torque lubricant but only the topside of the washer. The head side of the washer should be as dry and clean as possible for best results. We have performed this trick several times and it works.
Pick the Right O-Ring
The Gen III and IV LS engines use two different O-rings to seal the pickup to the oil pump. In the midst of swapping parts, it’s easy to get confused and use the wrong O-ring. The result is the oil pump will be unable to pull oil up from the sump. Zero oil pressure is the result. That’s not a good place to be, but picking the right O-ring is easy if you know where to look. Melling offers a chart that will dial you right in.
If the stock oil pump pickup has an O-ring groove in it or is tapered where it enters the oil pump, that design uses the factory red O-ring. This is replaced with the Melling green O-ring. If the pickup tube is straight where it enters the pump and it uses the blue OEM O-ring, then use the Melling black O-ring. Both O-rings are supplied with each new Melling oil pump.
New or rebuilt engines should always be pressure lubed before you start them for the first time. The challenge with the LS is the oil pump is driven by the crankshaft so that precludes spinning the oil pump separately. Summit Racing offers a 3-quart pressurized tank that can be filled with engine oil and connected with a braided line to the oil pressure port of an LS engine and then charged with pressurized air—usually 50-60 psi.
If you’d rather build your own pressure pre-luber, we built one using a hardware store 2 1/2-gallon bucket, a small-block Chevy oil pump, hoses, fittings, and some scrap aluminum plate. We mounted the oil pump to the inside of the sealed lid using 1/8-inch aluminum plate as reinforcement. We drilled and tapped the pump outlet for pipe thread to adapt a -6 male AN fitting and then cut the stock 5/8-inch pickup tube in the middle and extended it with a length of heater hose to the bottom of the bucket. We then used an AutoMeter adapter fitting to attach the outlet from the oil pump to the LS oil system. You can use that same port mentioned in the pre-lube tip. Finally, we drilled and tapped a metric bolt that fits the drain plug hole to allow oil to return to the bucket.
We drove the oil pump with a 1/2-inch electric drill motor. The return line allows us to run the pump almost constantly. The only issue we discovered is we have to stop pumping occasionally to allow the oil to return to the bucket. We’ve used both our homemade pressure pre-luber and the Summit tank several times on new and rebuilt LS engines and both work great.
AutoMeter offers a nice kit that adapts standard 1/8-inch NPT thread temperature or pressure gauges to the metric LS engines. The kit comes with two metric adapters; a low-profile temperature sender; and a 10K, 1/2-watt resistor. The first adapter is a 12x1.5mm to 1/8-inch pipe NPT (PN 2277, sold separately) to mount the water temperature sending unit. Be very careful when tightening this adapter, as it is very thin and will very easily twist apart and fail—ask us how we know.
The second fitting in the kit is a 16x1.5mm to 1/8-inch NPT fitting that replaces the factory oil pressure sending unit for a mechanical or electrical pressure gauge fitting. Rather than purchase the entire kit, you can just buy the above water temp adapter and drill and tap into the oil pressure cover that sits just above the oil filter on most LS engines. This can be drilled and tapped for a standard 1/8-inch pipe NPT fitting for a manual or electric oil pressure gauge. The included resistor is often required to improve the tach signal from the factory ECU.
Oil Pump Alignment
The official GM recommendation for adding a new oil pump requires you to bolt the pump in place over the crank drive mandrel and then remove the cover and place two 0.002-inch feeler gauges on opposite sides of the gear. Once the gear is centered, the outer four bolts can be torqued and the cover installed and torqued.
This procedure takes time and a bit of dexterity. Kenny Duttweiler showed us a shortcut that works and saves time. Install the oil pump over the drive and then gently tighten the mounting bolts to the block. Now, spin the engine over gently about four or five revolutions. The gears in the pump will align themselves and then all you have to do is torque the pump in place.
The classic line is “Trust but verify.” That’s what we did, learning that Duttweiler, of course, was right. The clearance was right at 0.002-inch all the way around the gears. So try this—and verify it for yourself! It’s the little things like this that make assembling an LS a nearly pleasurable experience.
Chasing Small Parts
When building a new LS engine, it can often be the smallest parts that cause the most grief. To make your life easier, several companies, including Summit Racing, have assembled the most in-demand parts so all you have to do is order one part number as opposed to five. The Summit kit includes the large coolant plug, the barbell, the small oil pressure passage plug, and three oil and water passage plugs.
This kit is designed for new blocks or used ones that have been completely stripped for cleaning. Each part is also available separately. The very large coolant drain plug requires a 17mm Allen wrench to remove or install. Amazingly, our local hardware store had that exact wrench in stock. You will need this to install that plug. As a last tidbit, if you need LS block dowel-locating pins for the heads, you can make big-block Chevy pins work in a pinch.
Thinner Head Gasket
When swapping heads on an LS engine, you might consider trying a slightly thinner head gasket. Stock LS MLS (multi-layer steel) gaskets are generally 0.053-inch thick, but Fel-Pro offers a series of 0.041-inch gaskets in different bore sizes that will improve compression slightly. For example, a 6.0L engine with a thinner 0.041-inch thick gasket will increase the compression ratio by 0.25—or from 9.5 to 9.75:1.
One accompanying warning is you must measure piston-to-head clearance. Production LS engines often protrude the piston above the deck by 0.008-inch or more. This much piston above the deck reduces piston-to-head clearance down to 0.033-inch with the 0.041-inch gasket. This should be sufficient for steel rod engines that don’t spin above 6,000 but it’s worth noting. The accepted minimum piston-to-head clearance on most engines is 0.040-inch.
This isn’t going to be worth a bunch of horsepower but every little bit helps. The part numbers for the heads are listed in our accompany parts list. Also note that they are listed as left and right. Always make sure they are installed correctly to ensure proper coolant flow.
Rocker Trunnion Upgrade
The stock LS valvetrain is very robust, but as valvespring loads increase this places greater pressure on the stock rocker trunnion and its tiny roller bearings. Several companies, including Summit Racing, offer trunnion upgrades. The conversion can be accomplished with homemade tools, but the Summit tool includes a handy mandrel and magnetic base that makes the job really easy using a simple bench vise. We converted a set of 16 stock LS rockers in less than an hour using the Summit tool. We won’t run through the step-by-step, but after you do the first couple of rockers, it becomes really easy.
Pull and Push
Among the LS engine’s idiosyncrasies is the harmonic balancer’s lack of threaded bolt holes, which offers no way to bolt on a normal balancer puller. Kent-Moore offers specialized tools that are nice and work well, but are also expensive. We discovered a slick, Posi-Lock three-jaw puller that works exceptionally well. It is over $100 but does an admirable job. One advantage to this tool is that it can be repurposed for many pulling tasks. Summit also sells a set of tools that will both remove and install a stock harmonic balancer. These tools are available separately or as a kit. Finally, ICT Billet also offers a simple threaded stud with a bearing that is very simple and affordable as an installer. CHP
|Powerhouse – LS lifter holding tool||POW101046||Powerhouse|
|ARP M11x2.00 thread chasing tool||ARP-912-0011||Summit Racing|
|ARP metric thread chasing kit (4-pcs)||ARP-912-0010||Summit Racing|
|Summit LS trunnion upgrade kit, bearings||SME-143002||Summit Racing|
|Summit LS trunnion upgrade kit, bushings||SUM-141560||Summit Racing|
|Summit LS small parts kit||SUM-G-1585||Summit Racing|
|Summit Pressure Pre-luber||SUM-CSUM9164||Summit Racing|
|Summit LS harmonic balancer installer||SUM-900135||Summit Racing|
|Summit LS balancer puller and installer kit||SME-K-906008||Summit Racing|
|Mr. Gasket front cover seal tool||MRG-LSTC1||Summit Racing|
|Mr. Gasket front cover seal tool||MRG-LSTC2||Summit Racing|
|Mr. Gasket rear cover seal tool||MRG-LSRC1||Summit Racing|
|Fel-Pro 0.041 head gasket, right, 3.945” bore||FEL-1160R041||Summit Racing|
|Fel-Pro 0.041 head gasket, left, 3.945” bore||FEL-1160L041||Summit Racing|
|Fel-Pro 0.041 head gasket, right, 4.100” bore||FEL-1161R041||Summit Racing|
|Fel-Pro 0.041 head gasket, left, 4.100” bore||FEL-1161L041||Summit Racing|
|Melling expansion plug kit (no barbell)||MPE-900BR||Summit Racing|
|Chevrolet, large LS coolant drain plug||NAL-11611351||Summit Racing|
|Chevrolet, barbell oil diverter plug||NAL-12573460||Summit Racing|
|Chevrolet valve lifter guide||NAL-12595365||Summit Racing|
|ICT LS head dowel kit (4 included)||ICB-551275||Summit Racing|
|AutoMeter LS gauge adapter fitting kit||ATM-5284||Summit Racing|
|AutoMeter temp sender adapter||ATM-2277||Summit Racing|
Photos by Jeff Smith