Here it is, the September 2006 issue of GMHTP, and our project 2001 Trans Am is eager to have an engine back under its hood--this time with 383 cubic inches of brawn. Having run the gamut of parts selection, block machining and cleaning, preassembly checks and part fitment, and finally the actual bolting-in of our Lunati rotating assembly in Part 1 of this series ("My First Stroker," August 2006), we probably fried a lot of readers' brains with information overload. Completing the short-block was a very time- intensive process, with lots of test fitting and dimension checking; fortunately, the hard stuff is basically over.
Hopefully, eager-to-learn do-it-yourselfers have had enough time to think over and digest all 18 pages of our last issue and are ready for more. If you're up to the challenge, follow along as we continue the assembly--bringing us ever closer to firing and testing our garage-built Gen III.
CAMSHAFT INSTALLATION
Like nearly all small-block GM engines produced in the last half century, the LS1 continues the tradition of a cam-in-block, pushrod-actuated valvetrain. While viewed by many techno-freaks as "old school" and dated, this setup yields dividends of increased durability, decreased engine mass, and lower center of gravity over an overhead-cam style engine. It also allows for a lower hoodline and therefore increased aerodynamic efficiency of the vehicle. Arguments of pros and cons of the design aside, what we're really interested in here is how to put such a valvetrain together, and we begin with the heart of it: the camshaft. In the interest of not inadvertently skipping any steps, we're going to continue to follow our GM service manual as closely as possible. Our machine shop had installed new cam bearings for us, and you should insist the same be done for your block. Just prior to installation, clean the cam using mineral spirits and coat all the cam bearings in the block (those you can reach anyway) with SAE 30 oil. Unlike earlier in the install, where too much oil could be a bad thing on some of the smaller engine parts (piston rings, for example), there's no harm in using large amounts of oil from here on out. So as we continue with the build, feel free to lube away!
Degreeing the Cam
We've just gone through what's known as installing the cam "straight up," with the crank keyway in the "0" position and the marking on the camshaft sprocket aligned with the "0" on the crank sprocket. Normally, cam manufacturers design their cams to be installed just this way, and it should yield the proper timing of valve opening and closing events with respect to the position of the piston in the cylinder. However, if you're a professional engine builder with a custom application for a specific cam, you may wish to second-guess the cam designers' choices and have valve events occur sooner, or in the alternative, delay them. By "advancing" or "retarding" the cam in this manner, one can alter characteristics of the engine's powerband. As mentioned earlier, SLP's timing chain makes this adjustment easy.
This author is not a professional engine builder, however, and wants to stick with Lunati's recommendations as to valve events. And theoretically, we've already done that. Nonetheless, it's common practice to degree the cam; that is, double-check that the timing of all valve events with respect to crank (and hence, piston) position match up to the specs provided on the cam manufacturer's cam card. This verifies that all parts have been manufactured correctly (highly unlikely with quality components from Lunati and SLP), but more significantly, the degreeing process ensures that the installers haven't made any errors of their own. This is a far more likely scenario--though we'd like to think not that likely!
We'll need some special tools to degree the cam, but in the interest of showing you how to avoid spending money on duplicate tools, don't be shocked when you see some tools we used earlier in the build in addition to a few new ones.
OILING SYSTEM INSTALLATION & MODIFICATION
The LS1's oiling system is fairly decent from the factory, although the stock oil pump can benefit from some improvement in capacity. To that end, we'll be swapping to a high-volume unit from SLP. Beyond this, minor modifications will be required to adapt the stock oil pickup tube and crankshaft oil deflector to our stroker crank and new pump.
ENGINE COVERS AND OIL PAN INSTALLATION
Older versions of the small-block Chevrolet (many still refer to the Gen III as a Chevy as a nod toward its ancestry, though it has very little in common with the original) had thin, stamped-steel engine covers and oil pan. But with the deep-skirt design of the Gen III, these items are stressed, machined-aluminum members that add to block rigidity. The oil pan also doubles as a mounting point for the clutch housing, so precise alignment of all components is critical for sealing as well as structure of nearly the entire driveline. The steps of installing these covers, while somewhat involved, are quite manageable if you get ahold of the right tools.
Front and Rear Cover
Before installing the front and rear engine covers, the crankshaft oil seals need to be replaced. Though GM designed these seals to last at least twice as long as those of previous generation small-blocks, there's no sense in reusing the stockers--particularly when you've already put thousands of miles on them. They're a press-in design, and as such a bit of care and some specialized tools are required. Their PTFE-coated sealing lips mean the areas of these seals that ride on the crankshaft should not be oiled; GM found that on past engines, oil breakdown would cause the crankshaft seals to become caked with degraded oil and additives over time, destroying the ability of the seals to maintain proper contact with the crank surface. The switch to PTFE coating means no more reliance on oil for lubrication and the elimination of this problem.
Stock timing chains, thanks to their less-durable design and construction, exhibit chain stretch over time and can throw off cam phasing. SLP's PN 55000 Double-Roller Timing Chain does away with that problem thanks to its nitrated sprockets and double-roller design, ensuring that the cam is always at the right position with respect to the crank. It's available for $179.95 or as part of a package: specify PN 55002 and get it together with SLP's oil pump for $339.95 (an overall savings of about 20 ducats). The bolts, drive gear and spacers you see, while packaged with the timing chain, actually apply to the oil pump and will be explained shortly. | 
The cam sensor (right) is now installed at the top rear of the block. The sensor reaches down to the rear of the camshaft and, by reading a spiral-shaped metal stamping just ahead of the rearmost cam bearing journal, detects the cam's rotational position. While back here, we also installed an item that we skipped earlier: the oil pressure sensor (left). To be able to torque it properly, a special GM tool is required (to fit over its plastic connector); not wanting to blow the cash on this item, we just put some Teflon-based sealant on the threads and made the sensor what we thought was the appropriate tightness. | 
Spray the crank snout with some WD-40, then gently guide the SLP crank sprocket on with a rubber mallet, tapping around the perimeter of the sprocket. Make sure the sprocket seats onto the snout all the way. Notice that the SLP sprocket has a variety of keyway options; while we are using the "0" keyway for now, the variety of slots provide for easy adjustability for cam advance and retard. (In a moment, we'll be degreeing the cam and determining whether we'll need to utilize a different one of these.) |
After using the Powerhouse crank turning socket to turn the crank until its sprocket has the "0" tooth marking pointing straight up, the timing chain and cam sprocket are installed. Thanks to the camshaft sprocket locating pin, it's impossible to put the cam sprocket onto the cam incorrectly. But note the marking near my index finger: this mark must face straight down. | 
When pushing the cam sprocket onto the cam and its pin, put your hand behind the block so the cam doesn't fall out the back of the block (the cam retainer plate only keeps the cam from coming forward; the sprocket, with its built-in thrust bearing, is what keeps the cam from moving backward while the engine is running). The stock cam bolts are reused and torqued to 26 lb-ft. | 
First, true top dead center (TDC) is found for cylinder 1. While the marks on the cam and crank sprockets indicate TDC, we need to be dead on and can't rely on eyeing the vertical alignment of these marks--plus, the trueness of these marks is one thing we're trying to verify. In lieu of purchasing a dedicated dial indicator for this purpose, we adapted our rod bolt stretch gauge for the purpose of touching the top of the piston (a simple loosening and adjusting of its set screws is all it took). The crank was then slowly turned until the gauge indicated the highest vertical travel of the piston in the bore. |