There are several areas where we can make huge mistakes when we assemble our motors. Some of these might just surprise you, but when you hear the logic, it will all make perfect sense.
The simple act of torqueing the motor can be much more complicated than we often think. Paying proper attention to details such as these are what make a great motor verses an average motor. All bolts are designed to be torqued differently for various applications. There are usually instructions on how to properly torque the bolt such as: a) whether to lube or apply a locking agent to the bolt first, b) exactly what kind of lubricant or locking agent to use, c) how to apply the lubricant or locking agent, d) the proper sequence for tightening a set of bolts such as head bolts, e) and of course, the proper torque to apply in measured steps.
What many engine assemblers will do after all of the bolts are torqued is to tap the top of the bolt head with a flat punch and hammer to help redistribute the torque loads along the threads. The bolt will have a distinct sound and if one bolts sounds different, then that bolt might not have seated properly or the threads may be defective or worn. Try this the next time you torque down the heads. You will hear a distinct ring to a properly seated bolt. Torque one bolt half way and listen to the different sound it makes when taped with the punch.
An improperly torqued bolt can lead to thrown rods, head gasket leaks, stretched or broken bolts, with obvious side effects, and other maladies. Know when to use locking agents on your bolts and when not to. For some applications where we are bolting into aluminum, there is a real possibility that some stronger locking agents will actual pull the threads out of the part when we remove the bolts.
Pre-Lubing the Parts
We need to pre-lube many of the parts that will be assembled inside the engine to help prevent initial startup wear and tear. Most parts will come with the proper lubricant to use. Don’t outsmart yourself and use a different lube than is provided. Contrary to some builder’s beliefs, these lubes are specially designed to be the right composition for the part you are installing and not just a cheap lubricant that saves the company money.
The areas of concern relate to how the lubricant will break down after the engine has been assembled and run. If the lube will not dissolve in the engine oil, then you will have problems with blockage in the oil passages or in the oil filters. Never use silicone or moly lubricants in your engine.
One area that even professional engine builders sometimes miss is in the lubrication of the piston and rings when installing them. We do not want to apply oil or heavy lubricants to the piston, rings, or cylinder walls when installing the pistons. The reason is that the oil will prevent proper break-in and seating of the rings against the cylinder walls. If oiled, these surfaces will take a longer time to wear in for a proper fit to provide maximum compression and reduced blow-by.
Experts tell us that the break-in related to rings and cylinders begins whenever we turn the crankshaft with the pistons installed, even turning by hand before final assembly. As we turn the crank to position it to install the next piston, the previously installed pistons/rings are already beginning the break-in process. This is very important to know. The initial compression numbers and the horsepower generated by the engine all depend to a great extent on the seal between the rings and the cylinder walls.
A light lubricant in the class of WD-40 works well on initial installation and does not impede the breaking-in process. Clean the cylinder bores, piston, and rings and then lightly lubricate when assembling them.
Sealants and Gaskets
Sealing the engine at the oil pan, crankshaft seals, timing cover, intake manifold, headers, and valve covers is a process that deserves attention. The areas that we need to seal are best sealed with quality gaskets. Today’s gaskets are of a much better design than those we have seen in the past.
Most of the time, we don’t need extra sealant material to be applied to the gaskets. Again, as with other operations associated with assembling the engine, read the instructions that come with the gaskets for help in knowing how to properly install and use the gasket.
Do not open your gasket kit, if sealed in a vacuum pack, until you are ready to install the gasket. If you open it and it becomes exposed to the air for long periods of time, the gasket will dry out and not perform the way it was intended. Leaks can develop and gaskets can blow out.
Go the extra dollar and buy quality gaskets that are made expressly for racing applications. These units are designed to be used in a racing environment that sees higher temperatures and increased pressures.
If you need to use a sealant material, if nothing more than to hold the intake gasket in place while you position the manifold, apply a thin line of material and press the gasket to help spread the sealant. Make sure you do not apply excess sealant that will ooze out from the gasket and become an obstruction to the flow of coolant, oil, or intake gases.
Proper Distributor Fit
A problem that has been seen in the past involves the distributor fit in both the areas of the bottom of the shaft to the bearing installed in the engine as well as the gear fit. We can avoid trouble down the track if we will check these fits before we crank the engine.
We have seen situations where the supplier to a major distributor machined the distributor shaft to a smaller dimension than was proper for the application. The shaft literally wobbled around in the larger hole and failure was just around the corner. Be sure to check the size of the bearing verses the diameter of the distributor shaft.
If the gears don’t mesh properly, they will wear very quickly and the distributor will exhibit erratic characteristics when we are trying to set the engine timing. These gears come in multiple sizes and we can order varying sizes to compensate for slop in the fit between the cam gear and the distributor gear. We can test the fit by rotating the distributor shaft while holding the cam still. There should be very little play in the gears.
Completing the Assembly
The final assembly involves bolting on the water pump, alternator, fan pulley, headers, water connections, and more. We need to be observant in certain areas to avoid trouble later on.
Closely align all of the belts that run the alternator, fan/water pump, and oil pump (if it’s a dry-sump engine). Any slight misalignment will result in premature wearing of the belts or worse, a thrown belt. Do not delay fixing a pulley that is not in alignment with the other pulleys.
When attaching the headers, if you use a high-heat silicone sealant, apply the material to the engine or header flange and then press the header onto the engine. Turn the bolts until the sealant material is flattened, but not too tight, and then allow the sealant to dry. Then later on, tighten the header bolts. If you don’t do it this way, the sealant may end up being too thin and you may develop header leaks later on.
The First Time You Start Your Engine
Most engine mechanics recommend that you always start the engine with the transmission in neutral and with the clutch engaged, as opposed to pushing in the clutch which pushes the crankshaft forward against the thrust bearing. Not only does this make the job harder for the starter, it puts unnecessary wear on the crankshaft thrust bearing because the oil has not yet begun flowing to lubricate it. Further, that thrust bearing is not designed for the magnitude of the load that a racing clutch can put on it.
After the first heat cycle after starting and running your engine, replace the engine oil. The original oil will have within it dissolved bearing lubricants, minute metal particles from break-in, and possibly sealant leftovers that don’t need to be in the oil once we go racing. Some engine builders like to use very thin oil for the first runs so that the rings and bearings will seat faster and more efficiently.
There is no more satisfying sound than your engine coming to life after the many hours of labor you have put into properly assembling all of the components. Follow all of the instructions provided and don’t be afraid to call the manufacturer and ask pointed questions and by all means, take your time and pay attention to detail. Winning race motors don’t necessarily have to be cheated up to out-perform the competition. A lot of gains come from using some of these tried and true techniques.