Crank Installation
The first major step of engine assembly is installing the crankshaft. While it is simple enough to insert the bearings and drop the crank in place, there are certain checks that need to be made before all is known to be right. Some of these checks, such as runout and bearing clearance could be made during the mock-up assembly, but the crank end-play needs to be verified after the main caps are torqued in place. Here are some points to pay attention to when installing the crank.
OEM cranks differ from most...
OEM cranks differ from most high performance cranks in the way the journal corners are finished. While OEM cranks typically featured an undercut radius where the journal's bearing surface meets the cheek, performance cranks will typically have added material forming a radius here. Performance bearings are manufactured with an edge chamfer to work with corner radius of the journals.
Rear main seals are typically...
Rear main seals are typically a two-piece rubber lip-type arrangement in older engines, while one-piece seals are found in most newer engines. The sealing lip faces inward towards the crankcase. Always check for areas of potential seepage, such as around the seal retainer, or mating surfaces of the main cap. A very light coating of sealant at these points can protect against leaks.
Assembly oil is all it takes...
Assembly oil is all it takes to properly lube the bearings during installation. We use Childs and Albert's engine assembly lube, but engine oil will also do the job. If the engine will be stored for a very long time before fire-up, a viscosity enhancer such as STP or Lucas oil stabilizer can be mixed with the assembly oil to give it holding power. Don't be tempted to use "old school" white grease on the bearings.
On engines with flanged thrust...
On engines with flanged thrust bearings, it's important to "set" the thrust bearing during assembly. This ensures that the thrust bearing is firmly shouldered against the main-cap and block in the forward direction of thrust. To "set" the bearing, slack the main fasteners at the thrust bearing position, and then run them in until they are seated. Using a heavy soft-face mallet, smack the nose of the crank rearward. Next, use the same arrangement at the rear rank flange to smack the crank forward. Now torque the main cap as normal.
Crank thrust clearance is...
Crank thrust clearance is measured by a dial indicator at the end of the crank. Use a prybar at the counterweight to work the crank forward and then back to read the end play.
Bearing caps must be installed...
Bearing caps must be installed in their original order and orientation. Most caps are numbered by the factory; make sure to mark them at disassembly if not. Torque the fasteners starting from the center main outward, using either oil or moly bolt lube on the threads and under the fastener's head as prescribed by the torque specifications. Check for free rotation as each main cap is torqued.
Some piston designs are symmetrical,...
Some piston designs are symmetrical, and can be installed in any bore, while others with offset pins or asymmetrical valve clearance pockets or domes may only be oriented correctly in specific holes. Positioning can be determined by looking at how the dome or valve notches fit the cylinder heads, while offset-pin flat-tops are usually marked with a notch or arrow indicating the front. Number each piston to a corresponding cylinder with an arrow to indicate the orientation in the bore.
Reciprocating Assembly
Loading the pistons and rods into the block marks a major milestone on the way to completing a build. There are several areas where a builder can get into trouble here, so careful assembly procedures are a must. It's best to first fully assemble all of the piston/rod assemblies, complete with rings, bearings, and lube, before knocking the first one in a hole. The orientation of the parts is important here. If using the stock rods, they should be numbered when the engine is disassembled, so that they can be replaced in the same position and orientation upon re-assembly. Many OEM rods are marked by the factory; if not, mark both the cap and rod.
For the beginning builder, pressed pins are best left the to machine shop, but the rod/piston orientation should always be checked. If putting together rods with floating pins, the rods need to be oriented correctly when the pistons are hung. Most rods, including aftermarket units, have a large chamfer on one side of the big end, and little or no chamfer on the other side. The rod needs to go in with the large chamfer to the cheek of the crank journal. A high quality lube such as Torco Assembly Lube from Valco Cincinnati is best for the pins. Lube the bores of the piston and rod, as well as the pin itself. Tru Arc style pin locks are easily installed with snap ring pliers, however most piston manufacturers these days supply Spiro Lox. Spiro Loxs are nearly failure-proof.
Spiro Loxs are installed by...
Spiro Loxs are installed by first stretching out the Loxs to separate the coils, and installed by winding them into the grooves in the piston. Some pistons are cut for double Loxs at each end, while others take just one. Always use two Loxs if the piston is cut for them.
It pays to take extra time in getting organized for this part of assembly, laying all of the components out on the workbench, in an order corresponding to their final position in the engine. Each hole should have a piston, rod, rings, and wristpin specific to its cylinder, laid out in order. The job is to load these parts into eight assemblies, and then install them in the engine.
Master engine builders can detect potential problems while assembling an engine just by feel. As each operation is performed, check the parts and feel for any snagging or binding. Make sure that the bearing seat fully into position in the rods, the rings fit the grooves smoothly, without hanging-up, sticking, or binding, and the pin retainer locks are seated fully in their grooves. There really is no margin for error in installing the reciprocating assembly. Each part should fit together without having to be forced into position. When the pistons are installed in the block, care must be taken not to hang a ring up on the deck, which can easily bend or break a ring. If something doesn't feel right, stop and investigate. Get the short-block done, and the engine project is well on its way to completion.
The ring manufacturer will...
The ring manufacturer will typically provide a chart with the ring stagger, which is the position of the gaps. Compression rings are usually installed 180-degrees apart. The best way to install rings is to insert one end into the ring groove, and wind the ring into position. Lightly oil the skirt and rings for installation. Most rings are designed with one side that must go up to operate properly, and are usually marked. Check the ring instructions for the specifics.
As with main bearings, rod...
As with main bearings, rod bearings may need extra chamfer to clear the journal radii of a performance crank, a feature found in most performance bearings. Bearings are often marked on the backside, indicating the upper (rod) and lower (cap) shells. The chamfer will go on the chamfered side of the rod. Rod bearings should get the same lube as the mains.
There are many types of ring...
There are many types of ring compressors, but the tapered-bore type is the best. These are available in a wide range of bores sizes from ARP. Before installing the piston, set the crank throw at bottom dead center, and lightly oil the bore. The piston should slide smoothly in the bore. Never try to force the piston into the bore if the ring hangs up--start over. Feel the drag on the piston as it slides down the bore, making sure it isn't binding. Once the rod cap is torqued, rotate the crank and check for smooth rotation.