In this buildup, the rods are torqued to the specs required by the company. When using aft
When we want to learn the important details of any operation, we can always rely on the experience of someone who makes a living doing it. This idea holds true when it comes to building and/or rebuilding race engines. Those who have done it a hundred times have found that things can, and often do, go wrong. By listening to them and following their instructions, we can avoid some common pitfalls.
Although this is not intended to be a complete engine-building guide, it will point out some of the simple, but dangerous, things sometimes overlooked that can affect the amount of useable horsepower and engine life.
Most, if not all, of the tips and procedures are the result of problems that have occurred and solutions that have been worked out by expert engine builders and tuners. If you discover just one tip that saves your engine, the time spent reading this will be well worth the effort. Let's get started.
1Engine TearDown Most often, the engine-building experience begins by tearing down a motor. This might be one built and used last season or one purchased from a junkyard. Regardless, attention must be paid when disassembling the motor. There are clues as to possible pre-existing problems, and if we are attentive, we can locate problem areas and fix them before investing money in new parts.
This cylinder block is being prepared with a torque plate in place for correct boring. It'
The rod and main bearings are an area where potential problems associated with restricted oil flow, binding, or improper clearances can be seen. Aside from a spun bearing or the obvious signs of galling or burning of the bearing surface, look further if one or more bearings are a different color than the others. This may be an indication of restricted, not blocked, oil flow. One or more bearings may be running hotter than the rest, and failure is imminent.
When a problem such as this is detected, take extra time to inspect and clean all oil passages. Another area is the felt torque on all bolts removed. If one or more bolts are already loose or take less effort than the others, the threads may be stressed in the block, or warping of the block or head may have occurred from overheating at one time or another. While the block or head may have been thought to be OK as is, you may now consider having it surface milled to make sure it is a truly flat surface.
This step is fairly obvious to most engine guys, but always mark the rods, caps, and pistons as to the original location as they come out of the engine if you intend to reuse them. You can stamp them by number, or those who don't own a number stamp kit can use an age-old method. Using a punch, make a series of dents to represent the cylinder number for the rod/piston combination and the end cap that goes with those as well as the main bearing caps. Use one dent for "1," two dents for "2," and so on.
Wash all new parts in a solvent to remove the protective coating. Once they are clean, pla
2Block and Head Preparation Prior to assembly, the block and heads will be cleaned by acid-dipping or other means to remove all of the old paint, sealants, and oil deposits that remain. It's now time to think about what machine work is needed before assembling the motor.
A limited amount of machine work may improve your chances of success with this motor. Usually the shop where you get your motor acid-dipped can also mill the block and heads, align-bore the block, and recut the valve seats for you. Price those jobs and see what you can afford. The areas of valve seats and alignment are well worth the cost and effort.
If you have several bolt holes that show worn threads, make sure to have them repaired by someone who knows how. Pay attention to those areas, not just before assembly of the motor.
Camshaft assembly lube is included with new cams. It should be applied to the lobes, distr
3Cleaning Process Request that the shop not heavily oil the block after the work is done. This will only cause you to have to thoroughly wash the block to remove all of the oil. Once the block is back from the machine shop, a light washing is always a good idea to remove any particles left over from the machining process, but you shouldn't have to scrub hard if the block has not been oiled. Don't let a few small patches of surface rust bother you. This can easily be removed by lightly sanding with a very fine grit paper.
Go through all oil passages and make sure all of them are free of sludge and grit. You can lightly oil the block with WD-40 or equivalent to prevent rusting until you can assemble the parts.
New parts are often coated with a heavy oil to prevent rusting. This protective covering has to be removed. Wash all new parts in a solvent that will dissolve the protective coating. Lightly coat the parts with a spray lubricant such as WD-40 or equivalent. Never use silicone lubricants. These contain water and will cause rust to form.
An area of concern is with the pushrods in your valvetrain. These units are coated with oil before they are packed. The rods are then packed lying on their sides, and the oil inside the rod lies on one side of the rod and gels. If this oil is not removed, the rod will exhibit strange characteristics when run at high rpm due to greater weight at one side of the rod. Uneven heating of the rod can occur also as a result of the residue oil, and this can cause the rod to bend. Even a small amount of rod displacement can cause unwanted valvetrain harmonic vibrations that inhibit the valvespring function.
Sometimes, a lubricant or locking agent will need to be used. The manufacturer will guide
4Ordering Parts One of the most important ways to ensure the success of your build is to communicate the correct information to your parts supplier. Use detail when telling them your parts needs. Nothing slows down an engine build like getting the wrong parts and then waiting for the new parts to arrive.
Tell the supplier your exact plans for the engine. A valvetrain kit intended for a 600-plus horsepower motor that will turn 8,000 rpm is no good for a Limited Late Model motor that will produce less than 400 horsepower and turn no more than 6,800 rpm. The harmonics will be wrong when using the high-rpm components in a lower-rpm motor. The valvesprings designed for high rpm will not live long at the lower rpm.
Measure your old pushrods to make sure the new ones that come with the cam kit will fit properly for the optimum valve geometry. This is extremely important to help provide the best flow at high rpm. If the pushrods you install are too short or too long, the geometry, or angle of the rods and valves to the rocker arms, will be wrong. This affects the timing of the opening of the valves as well as the amount of lift of the valve. Improper timing and reduced lift equals less horsepower for all of your effort.
5Preparing the Parts The rods, pistons, intake manifold, cam, block, and other internal engine components need to be deburred and thoroughly inspected before assembly. This includes removing all casting marks and rough edges left over from the machining processes. This step takes considerable time and effort, but cannot be overlooked if you intend for your motor to live a long and happy life. Rough edges on highly stressed parts are the exact areas where cracks will form. Once these edges have been removed, there will be much less chance that a rod or piston will fail.
The sides of the cam lobes are often left rough and jagged after the cam has been ground. You must take the time to deburr and smooth these edges so that when installing the cam you will not gall the cam bearings. Every hole where a piston pin, crankshaft, or piston will fit must be inspected and deburred where necessary. This means that the entire block must be gone over and worked on.
The camshaft should have been prelubed before insertion. Follow instructions step by step
All new parts must be inspected for defects, proper fit, and suitability for your application. We often see where the parts supplier makes honest mistakes or misreads your needs. The quicker you inspect the parts upon arrival, the sooner you can return them for the right part. Do not assume all of the parts are exactly what you ordered.
6Assembly 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 torquing the motor can be much more complicated than we often think. Paying proper attention to details like these can make the difference between a great motor and an average motor. All bolts are designed to be torqued differently for various applications. There are usually instructions on properly torquing the bolts, such as: whether to lube or apply a locking agent to the bolt first; exactly what kind of lubricant or locking agent to use; how to apply the lubrican cking agent; the proper sequence for tightening a set of bolts such as head bolts; and, of course, the proper torque to apply in measured steps.
After all of the bolts are torqued, many engine builders will 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 bolt sounds different, it 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 halfway and listen to the different sound it makes when tapped with the punch.
Bolting on external parts such as the headers requires the same amount of attention as any
An improperly torqued bolt can lead to thrown rods, head gasket leaks, stretched or broken bolts, and other maladies. Know when to use locking agents on your bolts. For some applications, such as bolting into aluminum, there is a real possibility that some stronger locking agents will pull the threads out of the part when we remove the bolts.
7PreLubing the Parts We need to prelube 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 builders' beliefs, these lubes are specially designed to be the correct 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, 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 even professional engine builders sometimes miss is lubricating pistons and rings when installing them. We do not want to apply oil or heavy lubricants to the pistons, rings, or cylinder walls when installing the pistons. 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 will tell us 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.
Robert Yates, one of America's top engine builders, once answered a fellow who asked, "What kind of oil do you lube the pistons with when installing them?" Yates said, "We are on a tight budget and don't use any lubricant." What he was really saying was, don't use heavy oil-based lube on the pistons and rings.
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.
8Sealants 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. Most of these areas that we need to seal are best sealed with quality gaskets of a much better design than those we have seen in the past.
Most of the time, we don't need extra sealant material applied to the gaskets. Again, as with other operations associated with assembling the engine, read the instructions that come with the gaskets to learn 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, 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.
9Proper 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 check these fits before we crank the engine.
The supplier to a major distributor once machined the distributor shaft to a smaller dimension than was proper. 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 versus 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 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.
10Completing the Assembly The final assembly involves bolting on the water pump, alternator, fan pulley, headers, water connections, and so on. We need to be observant in certain areas to avoid trouble later on.
Closely align all belts that run the alternator, fan/water pump, and oil pump (if it is 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.
If you use a high-heat silicone sealant when installing the headers, 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. Tighten the header bolts later. If you don't do it this way, the sealant may end up being too thin and you may develop header leaks.
Starting for the first time Most engine mechanics recommend that you always start the engine with the transmission in neutral and with the clutch disengaged. Pushing in the clutch, which pushed the crankshaft forward against the thrust bearing, makes the job harder for the starter and puts unnecessary wear on the crankshaft thrust bearing because the oil has not yet begun flowing to lubricate it. Furthermore, that thrust bearing is not designed for the magnitude of the load a racing clutch can put on it.
Replace the engine oil after the first heat cycle of starting and running the engine. The original oil will have 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 not a sound more satisfying than your engine coming to life after the many hours of labor invested to properly assemble all of the components. Follow all instructions provided, 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 outperform the competition. There's plenty to be gained from using some of these tried and true techniques.
Many teams choose to build their own engines due to convenience, budget limitations, or the simple fact that they can control what they have. There are important tips that professional engine builders have known for some time that can help make your engine build a success.