LS1 Engine Build - My First Stroker

After temporarily slipping the SLP oil pump drive gear over the keyway and onto the crank snout, we slide on Powerhouse's LS1 crank turning socket. This handy item not only allows the use of any 1/2-inch socket driver to turn the crank, but we'll see later in the build that it also provides for easy use of a degree wheel. The socket is held on by a hex set screw.

When putting rod bearings into the upper part of the rod and the rod cap, be careful: there is a top and a bottom half! Just watch that the chamfer in the bearing matches the chamfer in the rod (both will face the filleted edge of the crank). Also, you can tell the difference by looking at the back of the rod bearing: one is stamped with a "U" and the other with an "L".

Wipe the cylinder wall with a towel soaked in lacquer thinner until no more dirty residue comes off. We're removing metal particles left over from the cylinder hone, as they can cause premature wear of the piston, cylinder, and rings. In this and the following photos, we're already installed pistons into cylinders 1, 2, and 3 and are working on cylinder number 4 (passenger side bank, second from the front).

Get the throw of the crank to bottom dead center with respect to the cylinder you are working on. Coat the cylinder walls, the piston skirt, the upper rod bearing, the crank journal, and the ring compressor with oil. Put the ring compressor on top of the cylinder with its smaller diameter end facing down (it should install so you can't see the cylinder liner around it).

Now, making sure all ring clockings are still correct, slide the piston into the top of the ring compressor and start pushing gently downward.

The compression rings (top two rings) will have to be finger compressed to get them into the ring compressor. Before they'll even come close to going in, though, make sure the piston skirt has passed partially into the cylinder; this will self-align the ring compressor to the cylinder and allow the piston to start moving downward.

Once all piston rings have begun their descent into the ring compressor, begin tapping the piston lightly with the rubber butt end of a hammer. The ring compressor gradually shrinks in inside diameter from top to bottom, thereby compressing the rings enough so they will fit into the cylinder. The piston should not get hung up, but if it does, it means a ring has not properly made the transition from the ring compressor into the cylinder. Pull the piston out and start over lest you risk ring breakage.

While continuing to lightly tap the piston from above, reach below and carefully guide the rod onto the crank throw. Now is a good time to take one last look at the rod and upper rod bearing and make sure the chamfer on each is facing the fillet on the edge of the crank journal (and not the adjacent rod).

Put the rod's matching cap in place (making sure it and its bearing also face the correct direction), start the rod bolts by hand, then tighten the rod bolts just enough so that the cap seats (not shown). We'll be fully securing all of the rod bolts at the same time; seating the cap just ensures the rod will stay put on the crank while we install the remainder of the pistons.

Even though we won't be relying on a torque specification for the rod bolts, the threads of the bolt and the underside of the bolt head still need to be properly lubricated. The provided Lunati moly-based lube is used liberally on each bolt and helps ensure undamaged threads. You can see a dimple on the bolt head; there's another on the opposite end of the rod bolt. These allow a rod bolt stretch gauge to be centered on the bolt. Make sure these areas, as well as the contact points on the gage, are clean; we're measuring very small dimensions here and any contamination could ruin our readings.

Even though we won't be relying on a torque specification for the rod bolts, the threads of the bolt and the underside of the bolt head still need to be properly lubricated. The provided Lunati moly-based lube is used liberally on each bolt and helps ensure undamaged threads. You can see a dimple on the bolt head; there's another on the opposite end of the rod bolt. These allow a rod bolt stretch gauge to be centered on the bolt. Make sure these areas, as well as the contact points on the gage, are clean; we're measuring very small dimensions here and any contamination could ruin our readings.

With the rod bolt just snug, the Powerhouse rod bolt stretch gauge is installed onto the bolt. Some adjustment of the various set screws on the gauge will be needed to get it at the right length; the gage is designed with spring-loaded action to hold itself onto the bolt, and you want to be somewhere in the middle of this spring action (the spring has about 1 inch of travel). Adjust the dial indicator face to indicate zero, tightening the dial face nut (shown). Take the gage on and off of the bolt a few times, ensuring it goes to zero each time you are on the bolt. If it goes to different values you likely do not have the knob on top of the gauge tight enough (do this with the gage off the bolt and resting).

These suckers are to be tight, much tighter than the stock rods, thanks in part to their astounding 220,000-psi tensile strength. When we first started tightening the bolts, we weren't seeing the appropriate rod bolt stretch values, yet were turning the wrench so hard it felt like we might strip the bolts. A call to Lunati revealed something amazing: the torque needed to stretch these bolts the correct amount is roughly equivalent to 94 lb-ft! So addressing each rod bolt one at a time, we started off torquing to about 70 lb-ft...

...and then putting the gage back on to see how close we were. Based on this reading, we'd then incrementally up the torque until we got to spec. (Ideally, the gage is left on while the bolt is turned with a wrench instead of a socket; but the deep-skirt geometry of the LS1 block prevents a wrench from fitting in there.)

When you get it right, mark the bolt so you know that it has been tightened properly. With all of our bolts within the proper stretch value of 0.0050 to 0.0055 inches, measured torque readings varied between 74 and 91 lb-ft. This just goes to show you how simply relying on torque can give inaccurate actual bolt clamping values!

One last rod check: side clearance. Use a feeler gauge to ensure that space between each adjacent connecting rod is within the manufacturer's specification. GM specifies between 0.00433 and 0.02 inches, but that may differ for your particular aftermarket rod.

We promised we'd show you how the block clearancing turned out, so here it is: with just a touch of aluminum removed from the block, the head of each rod bolt now keeps a safe distance. The sucker swings through this area fast (rough calculations show about 116 mph at 6,500 rpm), so any contact would spell D-I-S-A-S-T-E-R.

With our entire rotating assembly fully secured in place, the short-block assembly is complete! In Part II, we'll continue the long-block assembly. Don't miss it!