Stroker Engine Build - My First Stroker, Part 2
The GM oil level sensor is a marvel of modern engineering, consisting of a piece of cork floating on the end of a piece of plastic. If the oil level in the pan falls below the sensor, the cork won't float and the ECU will be notified. Simple, yet effective! Reinstall this sensor now, and put in the oil drain plug while you're at it. The bottom end is now all buttoned up--it's time to move up top! | 
The Lunati hydraulic roller lifters are slipped into the stock lifter guides, also known as trays. These plastic trays ensure that the lifters remain in the correct orientation (so they roll on the lobes and don't get cocked sideways). Note that we've drilled some small holes in the lower area of the trays to reduce oil pooling, which will help prevent an excess of oil from splashing around in the tray and getting hot. | 
Considering that they are made out of plastic, it's surprising that the trays grab onto the lifters firmly enough to ensure they won't fall out as the tray is being handled. This grab action also means that, once installed, the lifters can't move without an external force: either the cam lobe must push them up, or the pushrod/rocker/valvespring must push them down. So, if you remove your rocker arms and spin the crankshaft over two full revolutions, the lobes will push all the lifters up; with the trays holding them away from the cam, this allows a heads-on cam swap! This is a pretty nice feature for enthusiasts that GM has incorporated. To install, simply line up the lifters with their respective bores and slide the trays into the block; torque the retainer bolt to 106 in-lb. | 
ARP sells this LS1 Pro-Series Head Stud Kit, PN 234-4316 ($372.83 suggested retail). It'll work for all LS1 and LS6 engines built through 2003; GM switched to all-same-depth bolt holes in 2004 so ARP has a separate part number for these later engines. Rated to 190,000 psi, the kit includes 12-point nuts but can also be had with hex-head nuts. There are a total of 10 8mm studs and 20 11mm studs; the stubbier 11mm studs (four in all) will install into the upper front and upper rear 11mm holes on each head surface. As to the 8mm studs, the GM service manual says to install the factory 8mm bolts using thread locking compound, so we'll use some on these too. As a side note, threadlocker is OK to use on all the ARP studs for a more permanent mounting, i.e., if you are taking heads on and off constantly on a race motor and don't want them threading out on you every time. | 
The ARP head studs will thread into the block easily by hand. If they don't, the holes haven't been properly cleaned (recall this process from last issue). We used a dab of ARP thread sealer (PN 100-9904, $10.21) on the block end of the studs just in case any protruded into a coolant jacket (from what we could tell, none did; but it never hurts to be safe). These studs only need to install with the slightest bit of snugness; just hit them with an Allen wrench to make sure they are all the way into their holes. | 
The head gaskets we've selected for this build are Cometic MLS (Multi-Layer Steel) units. With the ability to accommodate a maximum 3.910-inch bore and a 0.051-inch compressed thickness, they carry PN C5475-051 ($76.60 each). Three layers of stainless steel for strength and corrosion resistance comprise these gaskets. The two outer layers are Viton-coated, a material that can withstand temperatures of 482 degrees F. Perhaps best of all, no re-torque is necessary, meaning once your LS1's valve covers are on, they'll stay on. | 
After a thorough final cleaning of the block deck, the head gasket slides over the ARP studs. The ARP studs make it very easy to properly line up the gasket and cylinder heads, another advantage over bolts. The design of the Cometic MLS gasket promotes an even torque load across the sealing surface, which the company says results in a measurable reduction in bore distortion. | 
Before setting the cylinder head in place, the head gasket needs to be fully seated via a push about the dowel pin area (there's one dowel pin at the front and one at the rear). When installing the Cometic head gaskets, use care: it's possible to install them upside-down. We're looking at the front of the block here, and we see a small circular hole located just above the dowel pin. This is because coolant passages leading from the block to the head are smaller in this area. Around the dowel pin located at the rear of the block, the gasket should have large triangular and rectangular holes for coolant to flow through. | 
Before temporarily installing the cylinder head, Play-Doh is applied to the valve reliefs of one of the pistons (any will work; we chose cylinder number one). Once we're through with tightening down the head, installing pushrods and rockers, and turning the engine over, the head will be removed and we'll visually inspect to see if this Play-Doh has been squished--indicating a close call between the valves and piston. | 
The driver side cylinder head slides easily in place, helped in guidance and alignment by the ARP head studs. Iron heads are a thing of the past when it comes to today's engines, and we're thankful that the aluminum head weighs in so much lighter. To get an accurate reading of piston-to-valve-clearance, the head gasket must be compressed to its final 0.051-inch thickness; therefore, the head studs need to be torqued. | 
We do so using ARP's provided torque specs and GM's torque sequence (to be discussed momentarily when we put the heads on for good). With the tightness these suckers need to be, the entire engine stand will want to roll around on the garage floor; an assistant or well-placed foot (shown) will control this problem. As a side note, Cometic says it's OK to torque and retorque its MLS gaskets so long as they are not heat-cycled (i.e., the engine is not actually run). | 
The ETP rocker stands (black) are different from the stock stands in that they are thicker (around 0.670 inches in height to the bottom of rocker versus 0.502 for the stock ones), correcting for the differences between the stock head and ETP head. They also allow for the use of dowel pins (provided) to keep the stand located on the head more securely. We need to put in an intake and exhaust pushrod to actuate the valves on cylinder 1; we'll be using our length-checking pushrods mentioned in the tools article of our last issue. | 
Before installing the pushrods and rockers, we need to make sure the lifters are resting on the base circles of the intake and exhaust lobes of cylinder 1. One thing that sucks about the Gen III is that once the heads are on, the lifters are completely hidden--or so it would seem. Fortunately, the LS1 block has this hole knocked out in the valley area, giving a clear view of where the lifters in question are on the cam lobes (you may need to push the lifters down with the pushrods, as recall the that GM lifter trays hold the lifters up automatically). The lobes in question are the first and third back from the very front of the camshaft, and you can just see the roller ends of the lifters touching the cam lobes in this photo. | 
Lunati specifies a lifter preload of 0.020 to 0.060 inches, so we suggest pressing down on the rocker and gently rocking it back and forth, taking the pushrod out and lengthening it just a touch, and repeating until you have just gotten to where the rocker arm can't be rocked. Then, take the pushrod out and lengthen an extra touch. When you're satisfied, tighten the rocker studs to 22 lb-ft. Remember, preload has to be right to ensure our valve clearance measurement is right! With the rocker bolt secure, you should be able to rock the rocker lightly off the valve stem by hand to take up the remainder of the lifter travel before bottoming out the plunger (assuming the lifters have not been pre-oiled). | 
Now rotate the crank over two full revolutions (= 1 full cam revolution) to open and close the valves completely on cylinder 1. Since we now have the timing cover (and oil pump) on, we can't use our LS1 crank turning socket anymore, so we'll use another method to turn the crank. While one way to do this is to install an old flywheel bolt or two in the back of the crank and use a long screwdriver as a pry bar, the best way is still to put the old balancer bolt in the front of the crank, turn it until it's bottomed out, and use a 24mm socket to spin the sucker.' |
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