 Some 2001 F-bodies had the...  Some 2001 F-bodies had the "improved" LS6 engine block, while some did not. With a casting number of 12559378 (driver side rear of block), ours turns out to be the latter. The main difference between the two blocks is the improved cylinder-to-cylinder breathing passages cast into the bottom end of the LS6 block. Depending on who you talk to, these extra passages either free up a couple ponies (thanks to reduced parasitic losses), or they slightly weaken the block. Our take: whichever block you have, just stick with it. |
 At the front of the block,...  At the front of the block, the stock left front oil gallery plug, removed by our machine shop, can be reinstalled using Teflon-based pipe sealant on the threads; torque to the GM-specified 44 lb-ft. What GM calls the "engine block front oil gallery plug" is the pressed-in plug seen immediately to the left of the screw-in plug being installed here. It can be removed to provide access to the entire length of the oil gallery on engines that are especially dirty and require physical brushing inside the passage. |
 After reinstalling all other...  After reinstalling all other oil gallery or coolant plugs, double-check the cleanliness of the block, and you're about ready for assembly! Now is a good time to note that whenever you aren't working on the engine block, keep it covered up to prevent any dust and debris from contaminating the engine. This applies throughout the build; remember, dust and debris will prematurely ruin your LS1, and the engine isn't sealed until the heads are on and the oil pan is tight. That time is still a ways off! |
 The LS1's six-bolt main caps...  The LS1's six-bolt main caps fit rather tightly into the space between the oil pan rails, so they can be a challenge to remove once in there. To get the caps off, remove all the bolts (don't forget the side ones!) and gently rock the cap back and forth while pulling upward. A light hammer tap forward or back may be necessary, but do not use much force. Two long 3/8-inch extensions can also be used on either side of the cap to gently pry upward under the areas where the side bolts thread in. |
 Pop the upper half of the...  Pop the upper half of the main bearings in place in the block. These "upper halves," which now face down as engine is currently upside down, are the ones that have the holes in them for oil to enter the main bearing area. Put the lower halves of the main bearings in the main caps. |
 After wiping the crank main...  After wiping the crank main journals in mineral spirits, gently lay the crank in place in the block. Don't put any oil on any surfaces at this point; it will interfere with the measurement we are taking. With the crank in place, lay a piece of Plastigage on top of each main bearing journal, parallel with the crank centerline. |
STARTING OFF: THE ENGINE BLOCK
We're not going back on our promise that you can build a stroked LS1 yourself. But the one thing that would be highly impractical to do on your own is engine block machining. The tools required for this cost many thousands of dollars; but luckily they are in the hands of your local engine machine shop.
At the Machine Shop: Machining Processes and Options
Fortunately for late-model enthusiasts, GM designed the Gen III block so well that very little machining has to be done to freshen it up. The days of align honing block mains are virtually a thing of the past, and even decking of these blocks is often unnecessary. Generally, all you'll need to have the shop do is install a new set of cam bearings and perform a cylinder hone.
Cylinder honing is simply a term that refers to the precise removal of material from cylinder walls. This stands in opposition to boring, where a large amount of material is removed rather inaccurately. Honing gets the cylinder to the exact size needed and puts the correct surface finish into the metal of the wall. As mentioned earlier, with the aluminum-block Gen III, only a small amount of material can be removed from the cast iron cylinder liners. Simply put, they can't be bored--only honed.
Although rotating assemblies are available that include stock-size, 3.898-inch bore pistons (which would yield 382 cubes instead of 383), sticking with the stock bore size would be a bad idea on all but the most low-mileage LS1 block. Since cylinder taper and out-of-round were distinct possibilities on our 42,000-mile engine, we decided to have the cylinders honed a full 0.005 to accommodate 3.903-inch pistons. This is the best way to go unless you're starting off with a brand-new, never-used engine block.
The machine shop will measure your pistons and decide the exact size of the hone that needs to be performed based on the specified piston-to-cylinder-wall clearance given by the piston manufacturer. This means you'll have to have your pistons in your hands before taking the block to the machine shop.
We should note that while a so-called "deck plate" should ideally be used during cylinder honing (it bolts to the head surface to simulate bore distortion when the head bolts are tightened), it's not absolutely necessary; GM does not use a deck plate when honing blocks at the factory. If your local shop has done enough LS1s and you've heard good things about them, you should be OK--whether they have one of these deck plates or not. While the cylinder tolerances might not be within the kind of exacting specs Hendrick Motorsports looks for, you're probably not leaving that much on the table for a street/strip motor.
Back in Your Garage: Checking and Cleaning
Once you have the block back in your hands, don't just start assembling the engine. Since you couldn't machine the block in your garage, you're going to do the next best thing: double-check the machine work and, after this, make sure the entire block is clean enough for the Queen of England to eat off of.
PREASSEMBLY CHECKS AND FITMENT OF THE ROTATING ASSEMBLYWe're almost ready to begin assembly of the engine, but before we do, we need to make sure our rotating assembly fits properly in the block. To accomplish this, bearing clearances must be checked, clearance between the rotating assembly and the block must be assessed, and piston rings must be "file fit" to the block.
Checking Bearing Clearances
It is absolutely essential that main bearing clearances be within proper tolerance. If they aren't, reduced bearing life will result. Though the process is a somewhat-tedious "dry run" of the subsequent actual assembly, it cannot be skipped.
Checking Block-to-Rotating-Assembly Clearances
An increased crank stroke pushes the crank journals and connecting rods further outward toward the oil pan rails. In order to check and see whether any part of the rotating assembly is going to contact the engine block, we need to temporarily assemble the crank to the block--this time with oil in the bearings so that it can spin. In this way, a piston/rod assembly can be attached at each cylinder location, and the crank spun to see if there are any areas of interference.
Piston Ring Fitting
With most sets of piston rings, the "top" ring (ring closest to the surface of the piston) and second ring need to be custom-fit to each cylinder. This process involves installing each ring into a cylinder and measuring the gap between the two ends of the ring.
We suggest fitting all of the top rings first, followed by all of the bottom rings (or vice versa). This way, you won't be confused when filing the rings: the top and second rings usually look very similar. (With our Lunati set, the only real difference is the ductile iron second rings have a less shiny finish than the plasma-moly top rings.)
ASSEMBLING THE SHORT-BLOCK
Now that our entire rotating assembly is properly fitted to the engine block, we can finally start putting the sucker together for good. Though the preceding steps were involved and at times trying of the patience, they are absolutely essential and ensure that this LS1 will perform reliably for tens of thousands of miles to come. So without further ado, let's get to the real deal.
Begin Final Assembly
We strongly recommend following the GM service manual step by step for the entire build. You may be anxious to get your stroker up and running, but doing this--and carefully noting anything you need to skip and come back to--will ensure you don't miss anything (every step is critical!).
From the bare block, the manual dictates first reinstalling any block plugs that had been heretofore removed. There are several coolant and oil gallery plugs on the LS1 engine, and the service manual dictates where each one is located, what sealant to use on the threads (as applicable), and to what torque to tighten them to.
Crankshaft Installation
A crankshaft is a rather heavy item (Lunati's weighs about 50 lbs) so be very careful with the sucker; you might want a helper standing by to help you guide it into the block safely. Also, all journals (both main and rod) are highly polished and cannot be scratched without creating a problem; you'll note that we wait until after the crank is in place to install our ARP main studs, and the reason is so that we don't inadvertently contact one of them while we lower the crank in. Proceed with care!
Connecting Rod and Piston Prep
We're nearing the point where the pistons and connecting rods can be installed into the block. First, though, some preparatory work is in order. Specifically, the rods need to be disassembled, the rods must be attached to the pistons, and the piston rings need to installed and clocked onto the pistons.
Piston and Connecting Rod Installation
With the connecting rods hung on the pistons, it's finally time to shove the pistons down the bores and bolt the rods to the crank--for good. During this process, there will be some special tools involved, but fear not: just as the others we've used up to this point in the build, none of them are out of the price range of the budget do-it-yourselfer.
Connecting Rod Tightening
Once all of the pistons have been installed, one can begin carefully and systematically tightening the rod caps. Lunati uses rod bolt stretch measurement to make sure the rod bolts are correctly "tightened;" this is considered the most accurate method of evaluating whether a fastener has been properly "secured" (a more proper term).
 Now, install the main caps...  Now, install the main caps by laying them in place; they won't go fully down by hand, as remember they are a tight fit. Insert the main cap bolts and start them by hand (we're currently using the GM bolts for demonstrative purposes that you'll see in a second). To guide the caps down, alternate tightening the bolts side to side to ease the cap all the way down into place. Tighten all bolts initially to 15 lb-ft. |  GM's main cap bolts require...  GM's main cap bolts require a special method of tightening that we want to clue you in on; some aftermarket manufacturers specify this method of bolt tightening as well for both main and rod bolts. Basically, the bolt is torqued to 15 lb-ft and is then turned an additional specified angle as measured with a torque angle gauge. Following the sequence outlined by GM in the service manual, the inner main cap bolts get an extra 80 degrees of twist, while 53 degrees is the spec for the outers. Then tighten the side cap bolts to 18 lb-ft (no angle spec for these). |  Though we've only just put...  Though we've only just put them on, it's now time to take the main caps off. Undo all of the bolts, then gently rock each cap back and forth while pulling upward. Underneath each cap you'll find that the Plastigage has now been smooshed--let's measure it! |
 The sheath that the piece...  The sheath that the piece of Plastgage came in has markers on it; match the marker width to the Plastigage width and you've got your bearing clearance. Ours comes out to be somewhere around 0.0025; GM's service manual states a production bearing clearance range of 0.0008 to 0.0021, with a service limit of 0.0025 inches. While initially we were a bit concerned about this result, we consulted with Lunati's Mark Chacon and he explained to us Lunati's design philosophy on this as well as some enlightening information on bearing clearances in general. See the sidebar ("The Lunati Friction Package") for details. But to answer our question, our clearances are precisely within the specifications Lunati has designed the kit with. So, we're OK with the bearings we have and don't have to get a set of thicker bearings (they're readily available if needed). |  After wiping the used Plastigage...  After wiping the used Plastigage from the bearings and crank journals using mineral spirits, the main bearings are coated with SAE 30 oil and the crank is laid back in place. This type of oil is used because it is very thick, so there's no worry of it leaking out of the bearing area--we'll be using this type of oil throughout the build. Just torque all the mains to the initial 15 lb-ft: we only need the sucker to spin here. And spin it should! (You'll note we've switched to ARP main studs just to make sure they would thread in OK; they did, meaning block thread cleaning won't be necessary). |  Get a connecting rod out and...  Get a connecting rod out and undo the cap using a rod vise (we'll explain how--and why--to do this later in the story). Temporarily assemble a piston onto a rod, being sure to coat the piston pin and all other surfaces of contact with SAE 30 oil. Insert the upper half of a rod bearing into the rod and oil it up as well. |
 Choose a cylinder and turn...  Choose a cylinder and turn the crank so that the journal is at bottom dead center with respect to that cylinder. This gives the most amount of room to guide the rod onto the crank. Now insert the rod and piston carefully into the cylinder bore (coat it in oil too), being sure to not nick the crank journal as the rod approaches it. Use one hand to drop the piston down and the other to guide the rod onto the crank journal. |  While holding the piston fully...  While holding the piston fully down in its bore, flip the engine over and install the rod cap (with oiled bearing in place). Alternatively, you can get the rod cap on and the bolts started before the engine is flipped over, and this is better as it minimizes the risk of the piston falling out of the cylinder. (However, this block orientation is not as easy to photograph; hence our modus operandi.) Tighten the rod bolts until the cap is flush with the upper half of the rod; no need to torque it to spec or anything. |  Turn the crank slowly and...  Turn the crank slowly and see if there is any interference between the connecting rod and the block. For us, we found that the head of one the rod bolts nearly touched the block just beneath the bottom of the opposing cylinder liner. This definitely did not afford the mandatory 0.030-inch clearance required. Fortunately, the block is made out of aluminum in this area (and not the iron of the cylinder liner, it ends further up in the bore); so a touch of block grinding would be required. |