LS Engine Final Assembly Tips
Step-By-Step Final Engine Assembly Procedures
Step 1: Ready to Begin Assembly
The most exciting time of the engine build is now upon you, as all of your shiny new or refurbished parts will come together to make what you’ve been dreaming of: a fresh LS engine!Don’t let the adrenaline get the better of you, though: follow the below steps carefully (and in order) to ensure you don’t make any mistakes.
Step 2: Install Screw-In Engine Block Plugs
Flip the engine block upside down on its stand. Install any and all block plugs of the screw-in type, including oil gallery and coolant plugs. You should have noted where they all came from during disassembly. All of these are safe to reuse if their sealing washers are in good condition, but be sure to use Teflon-based thread sealant on the threads and under the sealing washer (new plugs include sealant on them). Torque this style of plug to 44 ft-lbs, or 30 ft-lbs if one of these plugs is an engine block heater.
Step 3: Install Press-In Engine Block Plugs
Install a new front oil gallery plug into the front driver side of the engine block. Apply medium-strength threadlocker to its circumference, and tap it in place using a flathead punch or similar instrument. Its outer lip should be recessed about 0.01 inch when fully installed. At this time, also install the rear oil gallery plug (a.k.a. barbell restrictor; use of a new one is strongly recommended). This item can simply push into place by hand, and will protrude just slightly when installed properly. Use no sealant on this plug, just make sure its O-ring is intact and lightly lubricated with engine oil.
Step 4: Install Main Bearings
Wipe each bearing shell seating surface in the block or main cap, as well as the back side of each shell, before proceeding. The upper main bearing shells (grooved) must now be installed into the engine block and the lower main bearing shells (solid) into the main caps. Be sure to install the thrust bearing shells into the center block bulkhead (bottom of first photo) and #3 cap. If you established the need to make one or more of these bearing shells undersize or oversize during pre-assembly, ensure each is being installed in its correct location. Each shell has a tab that fits into a recess in the cap or block, preventing backward installation (finger pointing in second photo). Make sure each shell is fully seated with its edges flush with those of the block or main cap—crooked bearings could spell disaster! Also ensure that your main cap locating dowels are in place in the block at this time (only certain engines have these; for example, the LS7).
Step 5: Insert Crankshaft Into Block (Professional Mechanic Tip)
Give the seating surfaces of the block and main caps, as well as the bearings themselves, a final wipe. Lubricate the upper main bearing shells. Do not forget to lubricate the thrust faces of the #3 main bearing! Spread some lube on the crank’s main journals, too. Now, grasping the crankshaft by the snout and rear flange, slowly lower the crank into the block. Use care not to nick any of the crank journals. Just as the crank is about to rest on the bearings, it may get stuck; slight adjustments in angle of the crank will likely be needed to get it to seat, as it will only go in just the right way. If gentle wiggling does not coax the crank to seat, pull the crank slowly upward and start over; excessive jostling will damage the crank journals or bearings. It may help to rotate the crank slightly as you lay it in.
Step 6: Install Main Bearing Caps and Bolts
After lubricating the lower main bearing shells, lay the main bearing caps in place, being sure to install each numbered cap in the correct location. The “wings” at the edges of the caps all face toward the rear of the engine, with the exception of the #5 cap (you can see this in the accompanying cap numbering photo). The caps likely will not seat fully by hand, as remember they are a tight fit between the deep-skirt oil pan rails. Insert the M10 main cap bolts and start them by hand. To guide the caps down, alternate tightening the bolts side-to-side to ease each cap all the way into place (don’t do this on caps that use locating dowels—tap the cap in place with a rubber mallet). The longer, non-studded main bolts go toward the center of each cap, while the studded ones go toward the outside. Only snug these bolts for now, then install the side cap bolts loosely. If you are re-using your old side bolts, apply some RTV sealant under the heads to prevent oil leakage.
(1) Though GM recommends these M10 bolts be installed dry, some engine builders use a small amount of oil on the threads to help prevent any possibility of thread damage during tightening (you can put some under the heads of the bolts, too). This is only permissible because these bolts use the torque-plus-angle method; doing this would destroy a proper reading if relying on a torque spec only!
(2) If not using GM bolts, follow the lubrication instructions provided by the manufacturer.
Step 7: Tighten Inner Main Bearing Cap Bolts (Torque Fasteners)
Torque all M10 inner main bolts (numbered 1-10 in the accompanying diagram), in the sequence shown, to 15 ft-lbs. Before proceeding further, you must use a rubber mallet to hit the crank rearward, then forward, with a rubber mallet. This aligns the thrust bearing surfaces and it is important to note that final thrust of the crank must be in the forward direction! Then use your torque angle gauge to twist these inner main bolts in sequence an additional 80 degrees. (See “Utilizing Fastener Stretch” on page 118 for reasons why this “torque plus angle” methodology is used by GM.)
Step 8: Tighten Outer Main Bearing Cap Bolts and Side Bolts (Torque Fasteners)
Now, torque all M10 outer main bolts (numbered 11-20 in the first picture), in sequence, to 15 ft-lbs. Once this is done, use your torque angle gauge to add an additional 51 degrees of twist to each outer main bolt, again in sequence. With all M10 main bearing bolts now tight, the main cap side bolts can be addressed. Torque each to 18 ft-lbs; there is no required sequence for these bolts save to say that you should tighten one side bolt and then the other before moving to the next cap. There is also no angle to add to the side bolts.
Step 9: Assemble Pistons to Connecting Rods
Unless you are using a press-fit piston pin (in which case your machine shop will already have put together your piston/rod assemblies for you), now is the time to assemble your pistons to your connecting rods. Read “Piston and Connecting Rod Orientation Rules” on page 113 before proceeding. Piston pin retaining clips vary in style; some are c-clips that install with snap ring pliers or similar tools, while others are spiral-type and must be stretched open to ease installation (shown in hand, such a spiral-type lock must then be worked into one side of the piston pin bore by simultaneously rotating and pushing it into its groove). Once you have a clip in one side, lightly lubricate the piston pin as well as the friction surfaces in the piston and rod with clean engine oil. Slide the pin through the bores in the piston and rod until it hits the clip on the far side of the piston. Then install the other clip atop the pin. Make sure these pin retaining clips are fully seated—they’ll normally click when they’re all the way in (a flathead screwdriver comes in handy for this)! Repeat for all pistons and rods, remembering to install any piston “notched” for reluctor ring clearance onto your #8 connecting rod (see Chapter 5)! At this point, we suggest marking the face of each piston with magic marker to correspond with any number previously scribed onto the rod.
Step 10: Determine Piston Ring Clocking
Most piston or piston ring manufacturers will provide specific guidelines as to ring “clocking,” or placement of the end gaps about the piston’s perimeter. If no clocking recommendations have been specified, you should follow the ring clocking diagram shown here during the below steps of piston ring installation (compression rings can easily be repositioned once installed on the piston, while oil rings are a little more tricky to slide against one another). The most important thing to note is that the oil control rails must be placed about 1-inch to either side of the expander end gap. Most modern ring packages don’t require precise clocking other than this, but you should still space the end gaps of the top and 2nd rings approximately 180 degrees apart.
Step 11: Install Oil Ring Support (Performance Tip)
Some high-performance LS pistons with a short compression height have an oil ring groove that intersects the piston pin bore (see the Appendix). Such pistons require installation of an oil ring support, which sits beneath the oil rings and provides the necessary structure in the area of the piston pin. An oil ring support must be installed before any piston rings, and this is most easily done using ring expander pliers. Oil ring supports will often have a dimple (pointing) that must face down in the area of the piston pin bore. This dimple prevents the support from rotating out of place while the engine is running—you do not want the gap in the support entering this area!
Step 12: Install Oil Rings
It is easiest to install rings if your piston is standing upright (so that you have two hands to work with); your rod vise lying flat on the surface of a table works well for this purpose. Beginning with the #1 piston, lightly lubricate the surfaces of all rings with clean engine oil. Install your oil ring expander into the bottom ring groove, which is the wavy-looking ring (it may have a piece of thin wire connecting its ends, like this one). Note that some ends of expanders simply butt together, while others lock in place. Then install one oil ring control rail below the expander and another oil ring rail above the expander. Oil ring control rails are easily installed by hand using a light twist (set one end in and hold it with your thumb), and ring expander pliers are not required. Note that if your piston has a small opening beneath the oil ring groove (near left thumb in second photo), you should move the rail endgaps past this area, i.e., further apart than just the 2:30 and 3:30 positions shown in step 10.
Step 13: Install Compression Rings (Special Tool)
Proceed to lightly lubricate and install your compression rings one at a time, being sure you are using the appropriate compression ring pair for the #1 piston (they should have been marked after ring fitting). Start with the 2nd ring, which sits in the lower of the two compression ring grooves and normally has a duller finish. Be sure to install the correct side facing up: this will be noted on the instructions included with your rings and is normally indicated by a small dot or a beveled/grooved inner or outer edge (which may face either up or down depending on your ring set). Use ring expander pliers to expand the ring just enough so that it slips around the piston; too much can damage the ring. If you do not have ring expander pliers, you can use your thumbs to push the end gap apart. Now install the top ring, again making sure to follow the ring manufacturer’s instructions on any bevel or dot placement. Once in their grooves, the compression rings should stick out a bit; this is normal and will help the rings put tension on the cylinder walls. Repeat steps 11-13 (as applicable) for pistons #2 through #8.
Step 14: Install Crank Turning Tool (Professional Mechanic Tip)
As with pre-assembly, a lot of crankshaft turning is required during final assembly. For this reason, it helps to install your crankshaft turning tool (if you have one) onto the crank snout at this point. Depending on the style of your tool, you may have to install your oil pump drive gear (which may be part of your crank sprocket) onto the crank snout before putting the crank turning tool on—see step 27. Again, if you do not have a crank turning tool, we recommend simply installing your old crank bolt and using a 24mm wrench to turn it.
Step 15: Install Connecting Rod Bearings (Critical Inspection)
If your rod caps are currently installed tightly to your rods, remove them in accordance with “Proper Connecting Rod Cap Removal” on page 96. Start with the piston/rod assembly for cylinder #1 (remember, each is unique!). After ensuring the bearing shells and their seating surfaces on the rods are clean, install the lower connecting rod bearing shell into the rod cap and the upper shell into the top portion of the rod. As with main bearings, each bearing shell will have a tab that will fit into a recess in the rod or cap, and the shells must be fully seated with their edges flush with those of the rod or cap. Also note that rod bearing shells are not always the same, and your rod bearings may have a top and a bottom half. This is especially true when using chamfered rod bearings to match high-performance filleted cranks. If this is the case, check the back of the bearing shells, which are often stamped with a “U” or “L,” indicating upper and lower shells. As a double-check, watch that the chamfer in the edge of such a bearing will face the filleted edge of the crank journal (i.e., the chamfer must face the front of the engine on odd-numbered cylinders and the rear of the engine on even-numbered cylinders). Lubricate the bearing shells with assembly lube.
Step 16: Turn Engine on Stand and Turn Crank to BDC (Professional Mechanic Tip)
Turn the engine on its stand so that the cylinder deck surface is as horizontal as possible. Give the appropriate cylinder wall one final cleaning, and lightly lubricate it with clean engine oil using a lint-free towel or assembly wipe. Then turn the crankshaft so that the rod journal for the cylinder you are working on is at its furthest point below that bore (bottom dead center). This will give the most room to guide the rod onto it. Also lubricate the crank rod journal with assembly lube.
Step 17: Adjust and Prepare Ring Compressor (Special Tool)
No matter what type of ring compressor you are using, lightly lubricate its inside surface with engine oil. If you have a tapered-sleeve ring compressor, set it roughly atop the bore. Adjustable sleeve-style ring compressors need to be adjusted until the cylinder liner can no longer be seen around its inner circumference. (Many machine shops make a slight chamfer in the top of the bores to ease ring installation, and you can see this in the first photo). As for band-style adjustable ring compressors, they should be wrapped snugly (not tightly) around the piston at this time, leaving the piston skirt exposed. Note: Use of band-style “oil filter wrench” compressors that do not lock to a set position is not recommended and can result in ring breakage!
Step 18: Install Piston/Rod Assembly into Ring Compressor
After verifying ring clocking, lightly lubricate the skirt of the correct number piston/rod assembly and insert it into your sleeve-style ring compressor (or simply insert the piston skirt into the bore if using a band-style compressor). Start pushing the piston very lightly downward by hand. Further minor adjustments to adjustable-style ring compressors may be needed so that the piston can slide through it while still holding the rings firmly. When using a sleeve-style compressor, you will probably need to use your fingers and press each compression ring into its groove, to allow it to enter the tapered section of the sleeve (shown in left photo).
Step 19: Avoid Rod Interference Problems (Important!)
Once the piston skirt has entered the top of the bore and all rings are being compressed, look underneath to ensure the connecting rod is roughly centered and not about to contact any part of the crank or block (or another rod, if one has already been installed onto the journal). Shown is a rod hitting a crank counter weight, a common occurrence. Twist the piston as necessary to get the rod at a 90 degree angle to the crank centerline, and you may also need to slide the rod to center it along the piston pin. Failure to correct these problems can destroy the rod or other components!
Step 20: Install Piston into Bore
Hold the ring compressor against the deck surface and begin tapping downward on the top of the piston with the rubber butt end of a hammer. If the piston stops at any point, do not force it! The ring compressor may be improperly adjusted and a ring may be hanging up on the bore lip. Some moderately forceful taps may be needed to get the piston to move, but anything more than this should be a red flag—in which case you’ll need to stop, pull the piston out, and make any necessary adjustments before trying again. Once you are certain the piston is going into the bore properly, reach underneath and begin guiding the end of the rod with one hand while continuing hammer taps with the other (you may remove the ring compressor at this point if you wish).
Step 21: Guide Rod Onto Journal and Install Rod Cap
As the piston moves down, some further slight twisting of the rod may be needed to help guide it past the crankshaft counterweight (and other rod, as applicable). As the rod nears the crank journal, use extreme care, as any part of the rod touching the journal surface could cause a scratch. Hold your hand around the journal with your index finger and thumb, keeping the rod bolt holes centered on either side of the journal (shown, be prepared to get a little lube on your hand). Once the rod is seated onto the journal, install the rod cap (remember to do so in the correct orientation). On aftermarket rods that use locating dowels, it is recommended that you tap the cap in place using a rubber mallet (in lieu of drawing it down with the bolts) to seat the cap. Either way, install and tighten the bolts until snug. Repeat steps 15-21 until you have installed piston/rod assemblies into all cylinders.
Step 22: Tighten Connecting Rod Bolts (Torque Fasteners)
Note: The procedures described in this step apply to engines using GM connecting rods and rod bolts only. If using aftermarket rods or bolts, follow the tightening procedure specified by the manufacturer, and read “Utilizing Fastener Stretch” below for more information. Flip the engine on its stand so that the oil pan rails are facing up. Starting with the #1 connecting rod, turn the crank so that both rod bolts are easy to access (the crank will be substantially more difficult to turn now that pistons and rings have been installed!). Torque each bolt initially to 15 ft-lbs. Then install your torque angle gauge and give each bolt an additional 75 degrees of twist. Mark on or near the bolt so you know you’ve tightened it, then ensure the rod can slide back and forth on the crank journal (if not, the rod bearings may be crooked). Repeat for each connecting rod until you have secured all sixteen rod bolts.
Early-style GM rod bolts must only be twisted 60 degrees (instead of 75). The most foolproof way to determine whether your bolts are of this type is to look at the area between the bolt head and the threads: if the bolt has a thick shank with a series of shallow, vestigial threads starting just below the head, it is an early-style bolt. Later-style bolts all had a narrower shank interrupted by a larger-diameter sleeve somewhere between the bolt head and threads (exact location varied). The photo compares an earlier (left) and later-style (right) bolt removed from a rod, but you can have a look now just by loosening the bolts and pulling them out enough to look at the shank. Early- and later-style bolts should never be mixed on the same rod!
Step 23: Install Crankshaft Position Sensor
Being sure to use some oil on its O-ring (replace if damaged), install the crank sensor into the passenger side rear of the block. Torque its retaining bolt to 18 ft-lbs. Make sure you are using the correct sensor for your engine and computer: black sensors are for 24X reluctor rings, while lighter colored sensors are for 58X rings.
Step 24: Short-Block Final Assembly Complete
The assembly of the short-block (or “bottom end”) is now complete! Take a well-deserved break, but be sure to cover up your engine while you’re gone to prevent contamination from airborne dust, bugs, and other unwelcome substances. Then, move on to the next step.
Step 25: Install Camshaft (Professional Mechanic Tip)
With the engine right-side-up on its stand, lubricate all cam bearings in the block that you can reach. Before continuing, be sure your hands are very clean, as it will be impossible to avoid contact with the camshaft’s journal and lobe surfaces during installation. The front of the camshaft is recognized by its bolt hole(s) and sprocket locating pin. Lubricate the two rearmost cam bearing journals (and the lobes between them) with engine oil, then insert the cam until it can rest these journals on the front two cam bearings in the block. (Please note that there is no need for moly-based “cam break-in lube” on LS camshafts thanks to their rollerized design!) The fact that Gen III/IV small-blocks use five equally-spaced, equally-sized cam bearing journals allows insertion of the cam segment-by-segment like this, meaning you can lube the journals and lobes as you go along, making the process a bit cleaner. When well on its way in (and little remains exposed to grab onto), an LS cam’s hollow construction lends itself nicely to the use of one or more long 3/8-inch extensions inserted into its central bore for added leverage (longer bolt(s) of the appropriate size and thread pitch can also be used, this is the only option for most single-bolt cams). Continue to insert the cam slowly and carefully (lest you mar the lobes or cam bearings), noting that more and more upward pressure will be required as the cam gets deeper into the block. When it is nearly all the way in, you can even insert a long 3/8-inch extension into the rear of the cam to help guide it the last few inches. Once the cam is in, remove the extension(s) or bolt(s), but be careful—the slight backward tilt of most engine stands means the cam may want to slide its way out the back of the block!
Step 26: Install Camshaft Retainer Plate
Lightly lube the built-in gasket at the back of the cam retainer plate (check once more that it’s in good condition). After wiping the corresponding surface on the front of the block, lubricate the thrust surface of the cam (its outside edge, which is inset slightly) and set the cam retainer in place. Use care not to accidentally push on the cam or it will slip backward and fall onto its lobes. Install the four cam retainer bolts and torque to 18 ft-lbs. If your cam retainer bolts are of a TORX-head design, the specification is 11 ft-lbs.
Step 27: Install Crankshaft Key and Sprocket (Special Tool, Professional Mechanic Tip)
Install your crank key into the crankshaft snout’s keyway using a rubber mallet. Be sure that it goes in squarely or it will be difficult to slide the crankshaft sprocket and/or oil pump drive gear over it. You may have installed your timing set’s crank sprocket onto the crank snout during pre-assembly, but if not, do so now. Spray some lubricant such as WD-40 onto the snout to help this process. Some aftermarket sprockets will simply slide over the snout and only require a few light hammer taps to seat fully on the crank. Factory-style sprockets should be started with light hammer hits, but will need to be pressed on the rest of the way using a crank gear installing sleeve (possibly combined with a harmonic balancer installer tool). The alternative to buying a sleeve is to simply use your old crank sprocket (shown)! This method will also require your old crank bolt and is easier and cheaper than buying a special sleeve. Press the sprocket on until it firmly seats against the crank, then remove your old sprocket, it should just come off by hand.
(1) Some cranks (expecially aftermarket ones) use a second key located further outward on the snout (to properly index aftermarket harmonic dampers and prevent any chance of it spinning on the snout). If using such components, install the second key at this time as well.
(2) If using an adjustable timing set, be sure to install the crank sprocket using the correct keyway you determined during pre-assembly.
(3) Do not use hard hammer hits to install the crank sprocket, this can cause severe engine component damage!
Step 28: Install Camshaft Sprocket and Timing Chain
Turn the crankshaft until the alignment mark on its sprocket is at the 12:00 position. Spin the camshaft by hand until the cam locating pin is facing to the right (roughly 3:00), making sure not to push the cam backward at all. This pin placement will help get the cam sprocket locating mark roughly where it needs to be. Lubricate the thrust surface at the back of the cam sprocket and soak the timing chain in oil. Once this is done, take your cam sprocket and hang your timing chain on it. Reach behind the engine with one hand to hold the cam from moving backward (this also allows you to turn the cam slightly if needed). Put the cam sprocket in place while simultaneously wrapping the timing chain around the crank sprocket. You may have to take the cam sprocket and chain on and off of the engine a few times until you get the marks on the cam and crank sprockets to line up vertically (they should be at 6:00 and 12:00, respectively). Start the cam bolt(s) by hand (some aftermarket timing chains afford very little slack, making this difficult); torque to 18-26 ft-lbs (cams with three small retaining bolts) or 66 ft-lbs plus 40 degrees (cams with one large retaining bolt).
(1) Be sure to use the correct sprocket markings determined during pre-assembly if using an aftermarket adjustable timing set.
(2) Engines equipped with VVT have the cam phaser mounted to the front of the cam sprocket, and the assembly is secured to the camshaft by an actuator solenoid valve in lieu of a bolt. It must be tightened to 48 ft-lbs plus 90 degrees.
(3) The timing chain tensioner (on engines so equipped) may need to be installed before the chain and cam sprocket. In this case, the tensioner will need to be temporarily deactivated using a pin or similar instrument while the chain and sprocket are put in place.(4) Engines equipped with a timing chain dampener (which sits in the area between the cam and crank sprockets) should install it at this time, torquing its bolts to 18 ft-lbs.
Step 29: Install Oil Pump
If your crank sprocket does not have the oil pump drive gear built-in, slide this item onto your crank snout now. Wipe the mating surfaces on the front of the block and back of the oil pump, then set the pump in place over the crank snout. You may have to twist the oil pump’s gear teeth so that they align with the teeth on the crank sprocket (or separate oil pump drive gear). No gaskets or other sealants should be used between the pump and block surfaces. Torque spec on these bolts is 18 ft-lbs. Once the oil pump has been installed, flip the engine over on its stand.
(1) If you are using an aftermarket double-roller timing chain, be sure to place any supplied spacers between the pump and block (and use any longer bolts supplied). Most aftermarket oil pumps do not require spacers as they are designed with the thickness of a double-roller chain in mind.
(2) While most pumps self-align properly to the block, LS7 oil pumps must be held flush or no more than 0.04-in. above the oil pan rails at the bottom of the block—no protrusion below the rails is acceptable! A straight edge or the GM J 41480 can be helpful in determining this—this is the same tool used to align the front and rear covers to the block (see steps 33-34). The procedure is similar for the LS9.
Step 30: Oil Deflector Tray Modification (Performance Tip)
Note: this step applies to high-performance applications only. For stock rebuilds, skip to the next step. When using a crankshaft with a larger-than-stock stroke, modifications to your oil deflector tray may be required to obtain adequate rotating clearance. To check for contact between your rotating assembly and the tray, set it loosely in place atop the main bolts and rotate the crank, watching and listening for any interference. Most commonly, this occurs between the tray and the heads of the rod bolts. To correct for this, mark the tray at all points of interference, then take it off of the engine and use a hammer and chisel to bend the tray in these areas. Do not close off any gaps in the tray completely—this will create oil flow problems. Reinstall the tray and ensure you have adequate clearance, noting that some extra space will be necessary to account for crank stretch at high RPM!As an alternative to modifying the oil deflector tray, you may also install a set of aftermarket tray spacers (see “SLP Performance Parts” on page 122), but be aware of the following: because the oil pump pickup tube mounts atop the tray on most engines, some modifications (i.e. slight bending of its bracket) may be required in order to correct for decreased clearance between the pickup tube’s screened inlet and the floor of the oil pan. This is easy to check with clay later during oil pan installation. A final note on oil deflector tray modification is that if you are using aftermarket main studs, they may require some of the holes in the tray to be enlarged slightly, which is easy enough to do with a drill or die grinder.
Step 31: Install Oil Deflector Tray and Pump Pickup Tube
Lay the oil deflector tray atop the main bolts, noting correct orientation (most are marked “REAR” at the back). It is a good idea to shoot some oil into the oil pump inlet at this point for initial lubrication. Install a new O-ring onto the end of the oil pump pickup tube. Coat the O-ring and the oil pump inlet opening with oil, then push the pickup tube into the oil pump. Ensure the tube is all the way in before inserting and tightening the retaining bolt, or else you may damage the O-ring or push it out of position. The retaining bolt gets 106 inch-lbs of torque, while the eight stock deflector tray nuts (one of which also secures the pickup tube bracket) receive 18 ft-lbs. If using aftermarket main studs and tray nuts (as shown here), use the torque specifications provided by the manufacturer.
(1) There are at least two different styles of pickup tube used on LS engines. Some tubes neck down near the end before bumping up to a flange. These tubes require a thicker O-ring, which is normally green in color. Other pickup tubes do not neck down and require a thinner (usually blue or black) O-ring; it is this type that is shown in the photos. An incorrect O-ring can cause loss of oil pressure and severe engine damage, so be sure you are using the correct type!
(2) If your oil pump has been spaced forward for use of an aftermarket double-roller timing chain, slight bending of the pickup tube bracket will be required for proper fitment.
(3) On dry sump engines (such as the LS7), the pickup tube is part of the oil pan, so only the deflector tray is installed at this time.
Step 32: Install Crankshaft Oil Seals into Front/Rear Covers
The crankshaft’s front and rear oil seals should not be reused, and must be removed from the engine covers and discarded. A hammer and flathead screwdriver can be used for this, though care must be taken not to score the aluminum surfaces of the covers. GM recommends waiting until the covers are on the engine to install new seals, but this requires special J-tools (which are invariably expensive or hard to get a hold of). The front seal is fairly easily tapped into place about its edges with a rubber mallet; do this slowly and gently or the seal will be destroyed. While the same can be done with the rear seal, you can also use this tool made by now-defunct Wheel to Wheel Power-train (which tightens to squeeze the seal into place, second photo) to make the job more fail-safe. A thin film of oil applied to the engine cover surfaces will help the seals press into place. However, the seals themselves are designed to be installed dry—do not lubricate their inner rubber surfaces! If you are afraid of botching this step, know that new front and rear covers are available from GMPP with seals pre-installed (see “GM Performance Parts” on page 125 for more information).
step 33: Install Rear Cover (Special Tool Used, Precision Measurement)
Before installing the rear cover, make sure the rear oil gallery plug (barbell restrictor) is still in place at the driver side rear of the block (see step 3)! Set a new gasket in place on the rear cover, using the first couple of threads of each rear cover bolt to hold it there. Wipe off, but do not lubricate, the crankshaft’s rear flange. You must be very careful when sliding the rear cover onto the block, as it is easy for the lips of the rear crank seal to become misaligned while doing this, resulting in an oil leak (updates to GM’s seal design have made this much more foolproof, though). The aforementioned Wheel to Wheel Powertrain tool’s aluminum “donut” helps ease an earlier-style seal’s transition onto the crank. Once all rear cover bolts are started by hand, you have a choice. The first option is to use a GM cover alignment tool (J 41480) to align the rear cover’s cover-to-pan sealing surface with the block’s oil pan rails before torquing the rear cover bolts to 18 ft-lbs. As an alternative, you may visually align the cover-to-pan sealing surface with the pan rails, tighten the bolts, and then verify no more than a 0.020-inch drop between the pan rails and rear cover using a straight edge and feeler gauge (any protrusion of the cover beyond the pan rails is unacceptable). This latter method will usually provide acceptable results since contact between the rear seal and crank flange helps roughly align the cover to the block.
Step 34: Install Front Cover (Special Tool, Precision Measurement)
The front cover goes on next, being sure to use a new gasket behind it. This cover is most easily aligned using the same alignment tool used for the rear cover, along with an additional J 41476 tool to help align the cover side-to-side.(This latter tool was not used in the previous step since the rear seal had already been installed and was basically serving the same purpose). Install the J 41476 hand-tight using your old crank bolt before installing the J 41480. If you do not have access to these two tools, it is strongly recommended that you wait until after you install the harmonic damper (step 59) to tighten the front cover bolts. This will help align the cover side-to-side and will of course require the oil pan to be installed after the harmonic damper as well. Either way, the front cover bolts get 18 ft-lbs of torque, and you must also verify no more than a 0.020-inch drop between the pain rails and the cover-to-pan sealing surface.
(1) Some aftermarket oil pumps require grinding to the inside surfaces of the front cover for proper fitment. Be sure to clean all shavings from the cover and seal after doing this.
(2) The LS7 does not use the J 41476, but rather its own specialized set of cover alignment tools, which require that the front crank seal not be installed until afterward. Absent access to these tools, it is recommended that you take the route of installing the harmonic damper first to help align the LS7’s front cover. The LS9 installation is similar.
(3) Engines equipped with VVT have provisions for actuating the cam phaser mounted to the front cover (you should have noted their layout during disassembly), so be sure to install these components now as well.
Step 35: Prepare to Install Oil Pan
Oil pan design varies substantially by engine and application, however all are installed using the same methodology. First, make sure any and all internal baffles, the oil filter adapter, the oil filter bypass valve, and like items that you may have removed during cleaning are in place and tight. Then set your new pan gasket atop the oil pan, using as many bolts as you can to hold it (it is not necessary to actually rivet the gasket to the pan, though you can if you wish). Now, apply a 1/4-inch bead of RTV silicone at each of the four meeting points of the block and front and rear covers. You will note that the front and rear cover gaskets protrude toward the pan gasket slightly at each of these points, but this RTV is for extra insurance.
Step 36: Install Oil Pan (Precision Measurement)
Now set the oil pan in place on the engine block. Depending on the baffle design of your pan, it may not drop straight down, but rather require some wiggling and/or angling to install. A properly installed pan will sit flush on the engine block; if it does not, your pickup tube may be hung up in the oil pan baffle(s), so lift up and try again. Once you are confident the pan has seated correctly, tighten the bolts only snug and use a straight edge to measure the pan’s location with respect to the rear of the engine block. Because the oil pan forms a structural part of the driveline (heck, even some of the bellhousing bolts attach to it), this dimension is critical: the pan cannot protrude beyond the back of the engine block, and may only be set forward 0.010-inch on most engines. On some engines, a maximum of just 0.004-inch is considered acceptable! After making any necessary adjustments to get the pan location correct, tighten all the short oil pan bolts to 18 ft-lbs. and the two long pan-to-rear-cover bolts to 106 in-lbs (most engines; pan and bolt style may vary). After verifying pan alignment is still acceptable, replace any and all sensors you previously removed from the oil pan (for example, the oil level sensor and oil temperature sensor, these vary by application).
Step 37: Install Camshaft Position Sensor
Turn the engine right-side-up on its stand. On Gen III engines, the cam sensor slides into the top rear of the block, and its retaining bolt is tightened to 18 ft-lbs. On Gen IV engines, the sensor is installed into the front cover, and its bolt gets 106 in-lbs. (the sensor on VVT-equipped engines is similar but not identical). With either style, be sure to use some oil on the O-ring. Many Gen IV engines also have a wiring harness extension and bracket (leading to the bottom of the cover) that you may wish to install now.
Step 38: Install Valve Lifters and Guide Trays
The best way to install the lifters into the engine is to first insert them into the lifter guide tray. Apply some engine oil to the grasping areas of the tray, then slide the lifters in. Because the tray grabs onto the flat areas on either side of the lifter, the lifters will only go in one of two ways, with either being acceptable (orientation of the lifter’s oil hole on the side does not matter). Then spread oil on all surfaces of each lifter—roller tip included—and push the tray into place in the engine. Each lifter should slide easily into its bore. On some engines, the shape of the tray dictates that it can only be installed in one orientation, but on others this does not matter. Tighten the lifter guide’s retaining bolt to 89-106 in-lbs—do not overtighten and crack the tray! Repeat for the other three trays until you have installed all 16 lifters.
(1) It is recommended that you not soak hydraulic lifters in oil before installation, as this can interfere with proper rocker tightening (stock rebuilds) or with valve lash adjustment (high-performance rebuilds using adjustable rocker arms).
(2) On AFM-equipped engines, the lifters for cylinders 1, 4, 6, and 7 look slightly different, mainly in that they have built-in springs that allow them to follow their cam lobe profiles while deactivated. Be sure to install them into their correct locations. The areas that the guide tray grabs onto are also of a different shape on these cylinders.
Step 39: Press in Cylinder Head Locating Dowel Pins
There are two dowel pins for each deck surface of the block, one at the front and one at the rear. It’s best to not reuse your old dowels, so install new ones now. Each must be pressed into its hole as completely as possible, and light hammer taps may be needed to do this.
Step 40: Lay Head Gasket on Block
Wipe the deck surfaces of the block clean one last time before proceeding. Tilt the engine in its stand so that one deck surface is horizontal. Take a head gasket and place it on the block, noting any markings on the gasket such as “FRONT” or “THIS SIDE UP.” Some gaskets are unmarked; to determine their orientation, note that because the rear portion of many LS blocks has more coolant passages between the block and heads, these must match any corresponding holes in the head gasket. Also, you may have to press down on the lower corners of the gasket to seat it onto the dowel pins.
Step 41: Inspect Cylinder Head for Gasket Incompatibility Recess (Critical Inspection)
Some early Gen III heads have a recessed area along the edge of the deck surface, just below the number 3 or 6 exhaust port (the head shown does not have the recess, but it would be exactly in the area pointed at). If your head has a recess, you cannot use GM’s newer-style MLS head gaskets, but must rather use a GM graphite-layered steel core gasket. See Chapter 4 for a comparison photo of these two types of gaskets. In the case of aftermarket gaskets, consult with the manufacturer for head compatibility information. If your heads are not currently assembled, follow “Cylinder Head Assembly” Workbench Tip before proceeding to step 42.
Step 42: Install Cylinder Head and Bolts
Make sure that the deck surface of the head is completely clean. Grasp a head along its sides (holding fingers inside the intake ports works well) and set it in place atop the head gasket. Ensure that it locates properly on the dowel pins. There are fifteen head bolts: ten that are large in diameter (M11 thread on most engines) and five small in diameter (M8 thread). Insert them at this time and turn them until they are just barely snug against the head.
(1) If you have a 2003 or earlier block, two of the M11 bolts are shorter than the rest, and these must be installed at either end of the top row of M11 bolts (locations #9 and #10 in the diagram shown in the next step; there is one shown being inserted in the photo to the left). On 2004 and later blocks, all M11 bolts are of the same length.
(2) While you must always install new M11 bolts, your old M8 bolts can be reused so long as you apply medium-strength threadlocker to the first several threads.
Step 43: Tighten M11 Head Bolts (Torque Fasteners)
Refer to the accompanying image for bolt numbering. The M11 bolts must be tightened in three steps. These bolts require a substantial amount of force to twist, so you may wish to have an assistant help you hold the engine stand from rolling around while you’re doing this!
FIRST STAGE: Using a torque wrench, tighten the M11 bolts numbered 1 through 10 in sequence to 22 ft-lbs.
SECOND STAGE: Now use a torque angle gauge to add 90 degrees of twist to these same bolts, again in sequence.
FINAL STAGE: The specifications to use in this stage depend on the style of head bolts that your block uses.
2004 and later blocks with all-same-length M11 bolts: add an additional 70 degrees of twist to the bolts in sequence.
2003 and earlier blocks with long/short M11 bolts: add an additional 90 degrees of twist to the bolts numbered 1-8 in sequence. Then add 50 degrees of twist to the shorter M11 bolts in locations 9 and 10.
(1) For engines using M12 head bolts (such as the LS9), refer to your GM service manual.
(2) If using aftermarket head bolts or studs, refer to the installation instructions and tightening specifications of the manufacturer. However, the above tightening sequence should always be used.
Step 44: Tighten M8 Head Bolts (Torque Fasteners)
Once all M11 bolts are secured, use a torque wrench to tighten the M8 bolts numbered 11 through 15 in sequence to 22 ft-lbs. There is no angle to add to these bolts. With all head bolts fully tight, repeat steps 40-44 for the other cylinder head.
Step 45: Mask Off Intake Ports (Professional Mechanic Tip)
As the valves are about to become operational, you do not want stray bolts or other items accidentally entering the cylinders, requiring head removal. Avoid any chance of this by masking off the opening of each port—especially those of the intakes—with tape. Once applied, you may want to punch a small hole into each piece so that the engine can “breathe” as rockers are being installed and the crank is turned over (this latter concern doesn’t apply so long as you have not yet installed spark plugs).
Step 46: Install Pushrods
Lubricate the lower tips of all sixteen pushrods with engine oil, then slide each into place through its passage in the cylinder head. Press down on each one as it is inserted to make sure the tip is centered onto the lifter plunger, and also to push the lifter down onto the cam. For the moment, do not lubricate the upper tips of the pushrods.
Step 47: Prepare to Install Rocker Arms (Important!)
On engines using stock or small-duration aftermarket camshafts, it’s possible to install and tighten the rocker arm bolts eight at a time at just two different positions of crankshaft rotation. However, since long-duration cams can cause some lobes to command lift at these positions, we’re going to go through a procedure that will work regardless of camshaft used. First things first, though: thanks to the rollerized design of factory LS rockers, we suggest submersing them in engine oil to help lube the internal bearings. After this, you must lubricate each tip with engine oil and liberally lubricate the pushrod cup (a specialized assembly lubricant is strongly preferred over oil for this area because of the amount of friction that will occur here at startup). Also lube the area that will contact the underside of the rocker bolt head with oil to assist in proper tightening, and use your oiling can to squirt plenty of oil between the valve spring coils onto the valvestems. Then, for cylinder heads where the rocker pivot supports are not a machined part of the head (this is the case with most LS heads), lay the rocker stands in place on each head; some aftermarket stands get bolted in place. Please note: because our method of rocker installation does not involve installing all rockers simultaneously, the factory stands must have at least 2 rocker bolts inserted into each of them at all times (spaced as far apart as possible) in order to prevent the stands from shifting out of place—the built-in factory alignment tabs alone will not stop this from happening!
Step 48: Install Rocker Arms (Professional Mechanic Tip)
Note: this step applies if using stock-style rocker arms only. If using aftermarket adjustable rocker arms, skip to step 49. The rocker installation process will require some attention—along with an assistant—because of the tendency of the lifter guide trays to hold the lifters off of the cam once they are raised, which masks lifter movement. However, when done correctly, the results will be properly tightened rocker mounting bolts on any application! 1. Start off by having your assistant use your old crank bolt to turn the crankshaft clockwise (most crank turning tools can no longer be used thanks to the front cover being in the way). 2. Hold downward tension on the pushrods for cylinder #1. This prevents the lifter guide trays from holding the lifters up artificially. Wait until the exhaust pushrod just begins to move upward (the exhaust is the one on the right when looking from the side of the engine). 3. At this point, lube the pushrod tip and install the intake rocker arm (make sure the pushrod enters its cup on the underside of the rocker properly) and torque its mounting bolt to 22 ft-lbs. 4. Continuing to hold tension on the exhaust pushrod, have your assistant turn the crank until your newly installed intake rocker rotates the intake valve open and then almost completely closed. Now install the exhaust rocker arm, torquing its mounting bolt to the same 22 ft-lbs. 5. Repeat this step for every cylinder until all sixteen rockers have been installed.
(1) Gen IV-style heads use rockers with offset tips for the intake valves. If you have this type of head, remember to install these rockers in the correct locations. (Recall, though, not all Gen IV engines use “Gen IV-style” heads, see our “LS Cylinder Head Evolution” Workbench Tip in Chapter 4 for more information.)
(2) If using an aftermarket cylinder head where the intake rocker mounting bolt intersects the intake port, it is not a bad idea to apply some RTV sealant to its threads.
(3) If you’re getting confused about which lifter is on the base circle of the cam at any given point, it helps to verify by viewing the lifters through the cast-in “gaps” at the front and rear of the valley. See above, picture 6. Unfortunately, this is only possible for cylinders 1, 2, 7, and 8 since these lifters are the only ones visible through these gaps. The alternative is to wait until after rocker installation to install the engine covers; this way, the cam sprocket will be visible during this step to help you sort things out.
Step 49: Installing Aftermarket Adjustable Rocker Systems (Performance Tip)
Note: this step applies to high-performance applications only. For stock rebuilds, skip to the next step. When using aftermarket adjustable rocker arms, the installation procedure is often very similar to that discussed in step 48, and you should always follow the instructions provided by the manufacturer when using such a system. However, here are a few helpful hints to guide you if you’re using a shaft-mount rocker system (this is not the only style of system available for LS engines, but they are by far the best). With installing an adjustable shaft rocker system, the main thing to keep in mind is to back the lash adjusters off all the way (i.e., as high as possible) so that they do not interfere with the process of tightening the mounting bolts. Also when installing and tightening their mounting bolts, since most shaft rockers are joined together as one pair for each cylinder, both lifters must simultaneously be on the base circle of the cam lobes (rotate the crank until a bit after the intake lifter returns to its lowest point). Once a rocker pair is installed, each rocker is then individually adjusted as follows: the lash adjuster is turned until it just contacts the tip of the pushrod (“zero lash”), then a specified number of turns (usually 1.5 to 2) are added to achieve the proper lifter preload. The lash adjuster is then locked in place via a nut.
Step 50: Install Valve Covers
With all rockers installed and adjusted (as applicable), we can button up the top of the cylinder heads with the valve covers. Most LS cylinder heads use four centrally located bolts to hold the valve cover in place. These bolts must be torqued to 106 in-lbs in an inner-to-outer sequence. New valve cover gaskets are mandatory, though the grommets under each of the bolts are OK to reuse.
Step 51: Install Valley Cover or LOMA
Set the valley cover (or LOMA on AFM-equipped engines) atop the block with a new gasket in place. Some aftermarket intake manifolds require substitution of the stock valley cover bolts, as their heads are too tall to afford adequate clearance from the floor of the intake. Either way, torque these bolts to 18 ft-lbs.
Step 52: Install Oil Pressure Sensor
On Gen III engines, install the oil pressure sensor at the upper rear of the block (next to the cam sensor, shown); tighten to 15 ft-lbs. On Gen IV engines, the oil pressure sensor installs into the rear of the valley cover and receives 26 ft-lbs of torque. Be sure to reuse the sealing washer under the sensor (as applicable) and use some Teflon-based sealant on the threads (new sensors normally already have sealant applied).
Step 53: Knock Sensor Installation
If your engine is a Gen III, the knock sensors mount into the top of block, in the valley cover area. Carefully lower each sensor into place and torque to 15 ft-lbs. If your engine is a Gen IV, the knock sensors install low on either side of block (not shown); the retaining bolt of each gets 15-18 ft-lbs.
Step 54: Installing Knock Sensor Wiring Harness
Note: This step applies to Gen III engines only. For Gen IV engines, continue to the next step. Because the intake manifold is about to obstruct access to the top of the valley cover, the piece of wiring harness that connects to the knock sensors on Gen III engines must now be plugged in. Run the wiring to the rear of the engine, and make sure the seals seat properly in the valley cover as well.
Step 55: Install Coolant Air Bleed Pipes
The last items to be installed before the intake manifold are the coolant air bleed pipes (or blockoff caps, if originally equipped at the rear—never install blockoff caps between the fronts of the cylinder heads!). As discussed when they were removed during disassembly, exact style of these pipes varies by engine; however, all are installed with bolts tightened to 106 in-lbs, making sure a gasket or O-ring is used in between.
Step 56: Install Intake Manifold (Torque Fasteners)
Before setting the intake manifold in place, install new intake port seals (car intakes, shown) or clip new carrier-style gaskets (truck intakes) in place. The intake port seals may want to creep out of their grooves, so ensure they are seated correctly before proceeding. Remove the masking tape from your intake ports and wipe the sealing surface of the heads, then place the manifold on the engine. Start its ten bolts by hand (use some threadlocker on their threads). You will need to make sure any brackets that attach to the intake manifold (and were removed during disassembly) are returned to the same place before doing this, as some are held by the intake bolts. Torque the bolts, in the sequence shown, a first pass to 44 in-lbs and a second pass to 89 in-lbs. (Note: For factory-supercharged engines such as the LS9 and LSA, refer to your GM service manual for installation instructions.)
Step 57: Install Fuel Rails, Throttle Body and Intake Manifold Accoutrements
Exact style of fuel rails and injectors varies by application, but they should be installed now using threadlocker on the bolts. Fuel injector O-ring seals should be lightly lubricated with engine oil to ease insertion, and again, if reusing your injectors, use of new seals is mandatory! Throttle bodies are installed via either 3 or 4 bolts, and a new seal should be used for this, too. Now is also a good time to install the MAP sensor, any PCV system hoses, brackets, throttle body sensor(s), and any other items originally removed during disassembly. The detailed notes and photos you took regarding these items will pay off big time here!
Step 58: Install Flywheel or Flexplate (Torque Fasteners, Special Tool)
Line up the “extra” hole in the flywheel or flexplate with that in the back of the crankshaft (if applicable). Apply threadlocker to the threads of the six bolts and install them. Torque to 15 ft-lbs using the sequence shown in the accompanying diagram, then repeat this sequence for additional stages of 37 and, finally, 74 ft-lbs. A flywheel holding tool is suggested for this step, though you can also have an assistant insert a pry bar into the flywheel/flexplate’s teeth (as may have been done during disassembly). Note that some ultra-high-performance engines such as the LSA and LS9 use an 8- or 9-bolt crankshaft flange; in this case, refer to your GM service manual.
Step 59: Install Harmonic Damper (Professional Machanic Tip, Special Tool)
Because of the high bolt torques needed for proper harmonic damper (“balancer”) installation, it is strongly recommended that you now install a flywheel holding tool to keep the crankshaft from turning over. There are two methods that can be used to press an LS damper onto the crank snout. The first involves using a harmonic balancer installation tool, which is fairly self-explanatory (not shown). But back in Chapter 2, we also mentioned that an alternate method is available, and here it is: acquire an M16 x 2.0 x 120mm bolt along with at least a few washers. Use this longer bolt (with the washers underneath to help it spin) to pull the damper onto the crank snout, switching to your old crank bolt if the longer one bottoms out. Watch to ensure the crank seal in the front cover stays intact during this process (do not lubricate the seal or the corresponding surface on the damper). With either method, once the balancer is on the crank as far as it will go, install your old crank bolt and torque to 240 ft-lbs. Remove it and ensure the crank snout is recessed no more than about 0.175-inch from the innermost ridge of the balancer. Only then may you install your new crank bolt, torquing to 37 ft-lbs plus 140 degrees of twist.
(1) Never attempt to press on the damper using just your old crank bolt! You will destroy the first few threads in the crank snout.(2) Some engines use a special locking washer between the front of the crank snout and the balancer (you should have noted this during engine disassembly). Be sure to install it during this step, as applicable.
(3) Because of the different length crank snouts used in some Gen IV engines (for example, LS4 and LS7), a different length bolt may be needed than that listed.
(4) While most factory cranks and dampers are not keyed to one another, many aftermarket ones are. In this case, you will need to align the keyway in the damper with the key in the crank for proper installation.
Step 60: Final Engine Assembly Complete
At this point, final engine assembly is roughly complete. We’ve installed every key engine component, and basically everything that’s left is better considered an accessory! Your stage of desired completion at this time may vary; you’ll need to think back to engine removal and disassembly to decide “how much further to go” while the engine is still on its stand, since further component installations may hinder your ability to easily install the engine into the vehicle and/or onto the vehicle’s removable subframe. Some of the items you may wish to bolt up now, but which we will not go through in detail, include:
- Starter motor
- Engine mount brackets
- Spark plugs
- Ignition coils and brackets
- Water pump
- Other accessory brackets
- Exhaust manifolds (use threadlocker on these bolts)
- Oil filter
- AIR system
- Dipstick tube
- Clutch pilot bearing/bushing
Most of these items are pretty self-explanatory to reinstall: just reverse the steps you went through during disassembly (see the Appendix for some helpful torque specifications). That said, move on to Chapter 9 for hints on installing, tuning, and breaking-in your newly-rebuilt LS!
Written by Chris Werner and Posted with Permission of CarTechBooks