LS1 Engine Build - My First Stroker

The area of the block that needed to be clearanced was marked with a magic marker, and then the rod was removed from this crank journal. The process of sliding the piston in, putting the rod cap on, and turning the crank was repeated for each cylinder. We found that every cylinder required a touch of grinding in almost exactly the same area.

Time for a helpful tip. Rod bolts, even lightly tightened, will set the rod halves together firmly; they can't just be pulled apart by hand. To get the rod cap off, loosen both rod bolts a couple of threads, remove your wrench driver, and tap lightly on your extension with a small (preferably rubber) hammer. Alternate between the two bolts to help remove the cap evenly. Also, when the bottom half of the rod is loose, flip the motor over and remove the rod bolts and bottom half of the rod; leaving the rod bolts in until you flip the engine over holds the rod cap loosely in place and ensures that the piston/rod won't come flying out of the cylinder accidentally.

When all cylinders have been marked for clearancing, (carefully!) take the crank out of the block and mask off each area to be ground; you don't want aluminum dust getting into the oil system. (We'll final clean the block one more time before final assembly, but there's no point in getting extra metal everywhere.) Don't worry about getting aluminum shavings on the cylinder walls; we're about to wipe them clean to get them ready for ring fitting anyway. We'll show you how the finished clearancing turned out later in the assembly.

One complete Lunati Pro Series ring set for a single piston consists of (top row, from left): plasma-moly top ring, ductile iron second ring, and oil ring support; as well as (bottom row): two oil ring steel rails and oil ring expander.

With a little WD-40 sprayed on the cylinder wall for lubrication, slip the ring in (here a second ring)...

...and use your ring squaring tool to get the ring completely horizontal in the cylinder. Pull up on the ring from underneath to get it flush with the bottom surface of the tool. Then, measure the ring end gap with a feeler gauge; at this point, the gap will be significantly tighter than you need it to be.

Head to the Powerhouse ring filer and give it a couple turns while holding one side of the ring squarely against the filing wheel. Take care not to go too far, as the coarse grit of the filing wheel will remove material quickly. Note also that the ductile iron second rings will cut even more quickly than the plasma moly top rings.

Install the ring in the cylinder with the squaring tool and measure again with a feeler gauge. If it's at spec now, great! If not, repeat the filing-squaring-measuring process until you've got the gap right.

After filing is complete, it's important to deburr both ends of the ring with a stone or similar instrument. This removes any stray pieces of metal that could score the cylinder walls or become lodged between the piston and the ring (thereby preventing the ring from properly rotating or expanding against the cylinder wall). Once you're happy with the deburring, move to the next cylinder; we suggest leaving the ring you've just done in its bore so you can't mix the rings up or start accidentally cutting rings for cylinders you have already fit rings to. Remember, we are custom-tailoring each ring to each bore, as the bores all vary slightly. When all rings have been file fit, take them out of the cylinders and label them with marker and masking tape.

As we mentioned earlier, our machine shop did not remove the engine block coolant plugs, but did take out a few of the oil plugs. The remaining oil gallery plugs that we hadn't reinstalled yet were coated with Teflon-based pipe thread compound, the equivalent to GM's 12346004 "sealant" that is mentioned in the service manual. The plugs were then torqued to 44 lb-ft using an 8mm Allen socket. Although the service manual said to reinstall the "barbell restrictor" (into the hole at the lower part of this photo) at this time, we were in the process of acquiring a new one. Thus, we took due note that this step had been skipped and that we had to come back to it later (remember: notes, notes, notes!!!).

Wipe the surfaces where the main bearings will sit--as well as where the main caps will seat--with a cloth soaked in mineral spirits. Hit the general underside area of the block while you are at it. Here and elsewhere, use a cloth that will leave as little lint as possible behind; a quality weave paper towel did the trick for us (Bounty). Also wipe the main caps themselves at this time. Though we did a thorough cleaning before, the block can never be too clean, and you'd be surprised how quickly dust can settle.

Pop the upper main bearings in place in the block and coat them liberally with SAE 30 engine oil. It's best to use a clean brush rather than your fingers (which, no matter how clean you think they are, are likely to have tiny particles on them picked up from working in the garage). The LS1's thrust bearing is the center main bearing; you can see that this bearing (bottom of photo) has material extending about its edges which will ride against a corresponding polished surface on the crankshaft.

Wipe the entire crank with mineral spirits now, focusing on the five main bearing journals (which are about to be oiled up). During this process, we isolated the crank from the floor with a clean trash bag, both to keep mineral spirits spillage in check and to prevent any floor dirt contamination onto the crank. Lunati's crankshaft is a beautiful piece of engineering, with its exclusive non-twist forging that allows for continuous granular flow at the microscopic level, improving resistance to fatigue versus a twisted forging.

Now, using as much care as you would guiding two grand in cash through the mean streets of Washington Heights (apologies for the somewhat loose metaphor), lower the crank into place in the block. Visible are the drilled areas on either side of the rod journals, which reduce the inertia weight of the crank, freeing up horsepower (not visible are the gun-drilled mains, which contribute to this also). We should also note that all journals are induction hardened to a depth of 55 thousandths, improving resistance to wear. Once the crank is in, wipe the exposed main bearing journals with oil.

With the crank safely in place, we can talk about ARP's LS1 Main Stud kit, PN 234-5608. Retailing for $240.02, it includes studs to replace all of the GM bolts holding the main caps in place (except the side bolts; they are a separate kit, PN 234-5608-SB, $29.50, which also includes an oil pump pickup tube bolt). It's a great way to strengthen up your bottom end, particularly with the added stress inherent in a high-powered stroker. ARP rates these 10mm studs at 190,000-psi tensile strength, and with them in place, the weak link in the block becomes the stock main caps.

Installing the ARP main studs is a simple task. The coarse threaded end of each stud ("bottom" of the stud in this view) threads into the block. The studs with more nut thread up top install toward the pan rails; they'll eventually have the crankshaft oil deflector secured atop them. While the studs need not be tight, they do need to be seated all the way, so make sure they are fully in using a 5/32 hex wrench. Clearly visible here are Lunati's 0.140 radii fillets at the edge of each main and rod journal; rounding the meeting of any two perpendicular surfaces reduces the stress concentration that could otherwise result in eventual material failure.

After cleaning, set the lower halves of the main bearings into the main caps. Note that the built-in tab ensures that they can only install one way, and be sure to install the lower half of the thrust bearing onto the number-three cap (GM numbers all the caps from the factory so you can't mix them up). Then coat the bearings with oil. Note that these lower halves of the bearings do not have passages for oil to flow through them; the uppers do as they are receiving the oil from the block.

Set the main caps in place, making sure each is put in the right location and facing the correct direction. Seat them by alternating tightening the nuts on either side, thereby pulling them down bit by bit. Clearly visible in this photo is another feature of the Lunati Pro Series crankshaft: the "Countoured Wing" counterweights, designed to deal appropriately with oil overspray coming out of the bearings as well as oil dripping from the valvetrain above. Unlike "knife-edge" counterweights--which simply split oil down the middle--the Lunati counterweights are specially contoured at their leading edges to direct oil (and air) away from the connecting rod journals. This reduces windage and frees up horsepower. Imagine the crank spinning clockwise in the photo and you will be able to envision this happening.

Use a liberal amount of ARP's provided assembly lubricant on the main stud threads as well as under the nuts and washers. This lubricant helps ensure that the nuts are tightened the correct amount (and that your torque wrench isn't indicating its torque prematurely due to unexpected friction between the threads, nut, washer, and block surface). A major advantage to ARP studs as opposed to bolts is that more accurate torque readings can be obtained as the threads are not being twisted into the block. Twisting also puts more stress on the block threads, which can create a concern for block life--especially with aluminum blocks like the LS1.

First, following GM's torque sequence, tighten the inner bearing cap studs to 15 lb-ft. Before the studs can be final tightened, the crank must be tapped with a hammer--first rearward, then forward. This aligns the thrust bearing, which again is located on the center main cap (between cylinders 4 and 5).

For the final main cap stud tightening, follow GM's torque sequence, but not their specs! Use ARP's instead, which are 60 lb-ft on the inner studs and 50 on the outers. Notice again that ARP does not use a torque angle spec, as their lubricant works so well that there's no fear of improperly lubed threads and the like. Different lubricants have different friction properties though; always use ARP's on their bolts and studs!