Engine assembly is like painting a house. The actual painting part is only completed, when all the very important preparatory work is com- pleted, and to get a good job done, all that prep work has to be done right. With an engine, there is a large amount of work that needs to take place before assembly. Some of that work is mental versus physical in that the correct components need to be first researched, then selected before purchasing. Once an engine builder has his or her list of the parts for the build, the next thing to do is collect those parts for assembly. Only then can the second phase of the build begin: the prep work. When the final assembly does begin, W-engine fans are in for a nice little bonus.
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A great tip is the use of lubricants during assembly. When an engine is running, all the internal parts receive a steady supply of oil. Keeping the parts oiled during assembly makes sure the parts have some form of lubricant on them during initial fire up, and that’s critical. Just like prim- ing an engine before first firing, all the internal parts need that oil to prevent metal-on-metal wear.
Pro builders usually start the on- stand assembly by installing the rest of the freeze plugs, the cam bear- ings, and any remaining oil gallery plugs needed for the build. The big- ger freeze plugs are best seated with a round-shaped driver, and many builders use a socket of correspond- ing size. A good coating of silicone sealer around the mating parts can add a little insurance to the friction fit of the plugs. The same holds true for oil gallery plugs, which are made in two versions. For most restoration and non-competition builds, the small friction-fit plugs, dabbed with some silicone sealer, are enough to do their job. In racing engines, it’s the usual practice to use threaded plugs. That means the hole needs to be tapped prior to assembly much like any other machine process. When it’s time for the threaded plugs to be installed, a dab of thread locker helps keep them in place.
Preassembly of some parts and assemblies is always an efficient way to prepare for a build. For a smooth final assembly, join the rods and pis- tons ahead of time. Fitting the wrist pins into the rods and pistons is the simple overview of what happens there and depending on the build, can be done with the aid of a press or by hand. If any retainers are needed for the pins, make sure they are cor- rectly in place at this point.
Once the pistons and rods are joined, one preferred option is to fit all the piston rings. Oiling them as they are fitted into the grooves of the pistons makes installation easier and keeps any damage to a minimum. Keep in mind, some 348/409 pis- tons are directional and need to be installed in a specific pattern in the bores and on the crankshaft. 409s are more prone to using such pistons than 348s. Likewise, high-perfor- mance W engines are also known to use such pistons.
Lining up the pistons on a bench and even numbering them is an old engine builder’s trick—some even stamp the number of the cyl- inder where they are installed on the connecting rod and rod cap. For those pistons that have a dedicated direction, a simple marking on the top or face indicating top and the fore/aft direction should work. Doing this ahead of time makes final assembly easier.
Checking and double checking includes watching for any burrs or sharp edges where they should not be. One example is the rings around the piston, particularly the oil-ring groove. The area where the rings are open and may have been filed down on their edge to fit the piston is another.
If a ring does not meet the clear- ance provided by the manufacturer, it must be filed down. Putting the ring into a vise that has protective jaw covers is the accepted way. The secure hold of the vise gives the per- son filing better control and keeps the ring from bending.
The last piece of the rod/piston combo is the connecting rod end where the rod cap bolts to the rod. This is yet another area of impor- tance, as it rotates on the eccentric journals of the crankshaft. As such, take care to match the caps to the rods and specific rod bolts. There is a large amount of force generated here so make sure all the right parts are used, whether for a stock or perfor- mance build.
The block must be thoroughly cleaned of oil, cutting fluids, chips, and other debris that could clog oil and water routes or damage engine parts. If the block is going to be painted, after cleaning is the best time. The same is true for the heads and any other core pieces to be painted. This cleaning philosophy holds true for all the pieces going into the engine such as the crank, rods, pistons, and so on, even though they won’t be painted. Professional builders not only clean every piece but lay them out in the assembly area and cover them with fabrics that do not shed, keeping contaminates at bay. Fibers, while capable of scratch- ing metal surfaces such as bearing or cylinder bores, can do worse damage such as clogging oil lines and water routes.
Another good pro trick is to have a checklist of all the components to make sure they are at hand. All the prep work on the parts should be done before they are presented to the assembly area. The idea of having the parts in view of the builder also helps make sure none are overlooked. Imagine finishing a build and find- ing one half of a rod bearing left over.
More prep work includes having all the necessary tools and equipment for the build and that may include thread lockers, anti-seizing lubes, cam coatings, and assembly oils and lubes. Having an aerosol can of parts cleaner is always a good idea, too. Pro builders often use one table for tools and equipment and another for the actual engine components as they go back and forth with tools. Small parts or fasteners are the bane of engine builders as they can get easily lost and end up inside the engine and cause extensive dam- age. Smart builders keep parts such as oil pan and timing chain bolts in small containers, already counted out. One builder likened it to surgery as the doctor/builder must account for every part and tool to make sure nothing ends up in the wrong place when the build is completed. There could be nothing worse than won- dering where that small, 3/8-inch socket went when it’s inside the cyl- inder bore.
One last pre-assembly tip is about fasteners. While it is para- mount to have all the nuts, bolts, screws, and other fasteners invento- ried for a build, it is just as important to have them all clean. Dirty bolts reduce effectiveness. In the case of a bolt or stud that is torqued, dirty threads give false torque readings. Even those fasteners not required to be torqued can give a false sense of being tight when dirt or contami- nants are on the threads or head. The same holds true for the condi- tion of the fasteners when reusing them. Are they rusted or corroded? How are the heads of the bolts? Are they rounded off on the corners? Do they still fit the wrenches and sock- ets without damage? By their very own design and use, bolts stretch. Eventually, any metal piece that is stretched fails. A builder can never really know how many times a bolt has been tightened, so many opt for new ones especially when the origi- nals may be more than 50 years old and possibly been exposed to the elements for years at a time. There is a heat/cool cycle to engines and if those are run to the extreme, the heat treat of the fastener can be affected. The last word on nuts and bolts is that they are one of the least- expensive items to buy for an engine build, and that makes them highly affordable for replacement.
All holes in the block should be thoroughly cleaned out, especially the blind holes. The least little object can block the bolt from traveling and even damage the threads. A common practice is rifling the threads, where a cleaning brush in inserted into and through the openings. Even blind holes can receive this cleaning pro- cess that should be done prior to the last block cleaning.
Valves and Hardware
With the head casting work done and the pieces all cleaned up for final assembly, the heads first receive the valves in a somewhat delicate and tricky assembly. The valves go in first and then need something to hold the valve in place while the spring or springs are located on the valve- stem. Then, with the spring(s) under compression, the retainer and keep- ers or locs are installed on the end of the valvestem. This is also the time when any shims for the springs must be installed. Repeating the procedure for all 16 valves finishes the job.
When all the parts are present and accounted for, along with the proper tools and supplies, the build usually starts with the last of the prep work—finishing the back of the block. Like most engines, Chevy 348 and 409 engines have freeze plugs that go into the back of the block. The same holds true for the rear cam plug and even the last cam bearing. These pieces need to go into the back of the block before the actual assem- bly begins as once the block is bolted to the engine stand, access to the rear of the block is very limited. These parts cannot be installed after the build, either. Smart builders install the rear freeze plugs, cam bearings, and cam plug. The easiest way is doing just that. The same holds true for any oil restriction plugs. These plugs restrict the flow of oil to the lifter gallery and are usually used in race-engine builds.
Finally, just before the block goes on the engine stand, the two steel dowel pins for aligning the bellhous- ing are driven into the back of the block if they’ve been removed. The easiest way to perform this is to stand the block on its nose with the back of the block facing up. The pins can then be driven in. That completes all the work on the back end of the block.
The bare block can now be bolted to the engine stand. A quick word about engine stands—make sure the stand used is capable of comfortably supporting the bigger W-engine’s weight. For selecting the proper engine stand, keep in mind a standard-style W weighs about 150 pounds more than a small-block Chevy. If a build contains more com- ponents such as a blower or extra drive/induction parts, remember to factor that additional weight into calculating the proper stand. Modern stands offer more stability with four wheels as opposed to those with only three wheels. A builder must rotate the crankshaft during assembly and that requires a twisting side motion on the block which by its nature is top heavy on the engine stand. One more tip on engine stands is the pos- ture of the builder. Having a good stance keeps both the builder and the stand in balance, helping to elimi- nate the stand falling over and caus- ing damage to people and parts.
One more tip the pros use is to always keep inspecting the parts. Check and double-check parts, assemblies and how they interact. A last-minute error found at this stage could save quite a few dollars, time, and work down the line. Just think of how much easier it is to work on an engine when it’s out of the car than in it. And remember all the work involved in installing or removing an engine and transmission.
Cam Bearing Installation
Cam bearings can be installed in the preliminary stage of assembly, as there is no machining to be done. A special tool is required, as is taking special note of the direction of the bearings that have holes in them. Those holes need to line up with the holes in the block, or oil is not able to flow to the cam bearings. The tool is used to install the bearings which, like the plugs, are a friction fit. Take care to ensure the bearing is properly located in the race of the block.
The next step is to fit the crank- shaft. For this very important stage, the engine’s main bearings are lightly oiled and installed, the crankshaft gen- tly lowered into place, and the main caps bolted in. The object here is to make sure the clearance of the crank- shaft is correct. That clearance varies with the types of builds and parts used and the manufacturer’s specs are the way to go. Most builders use microm- eters to measure the outside diameter of the crankshaft journals, measur- ing across the entire journal in two or three places to ensure a consistent size. For the other half of the crank- shaft-bore measurement, builders use dial indicators inside the bearings when they are in the proper position and under torque load.
Another way to check bearing clearance is to use a wax-like product called Plastigage, placed between the crankshaft and the bearing and com- pressed. Once the main caps have been torqued to their proper set- tings, they are removed to check the clearance. The width of that product shows the clearance by how much was squeezed and flattened. For most stock- and street-performance-level engines, this is adequate. Either way, it is cheap insurance to check every main to make sure the proper clear- ance extends throughout all mains keeping the crankshaft in its opti- mum working position. The crank- shaft is the foundation of the rotat- ing assembly, and as such, is the heaviest moving part in the engine. Give it a fighting chance to succeed and a good engine can be had. Ignore the basic needs of a crankshaft and the entire engine could be destroyed.
When the proper clearance is set and confirmed, the crankshaft is installed for the last time, and the main caps torqued to specs. Once the crankshaft is placed in the block, it should be checked to ensure that it is straight. A dial indicator should be installed and there should be no more than .004 inch of run-out. When using studs for the mains, most builders hand tighten them into the block until they are torqued down with the crank later. Builders point out that this is where some people get into trouble and end up applying double torque to the block. Double torquing accounts for the number-one failure in aftermarket blocks—it stretches and even rips the threads in the block. The same can easily happen in stock blocks, too. Remember this tip. When the mains are torqued down, so are the studs. If torque numbers for main studs are needed, builders suggest 5 to 10 ft-lbs, which is essentially hand tightening. Depending on the build, applying either an anti-seize lube or just oil are the most popular addi- tives for studs and main bolts. Many builders prefer to use an anti-seize lube when there are two dissimilar metals such as with an aluminum block or heads.
Torque Down Main-Bearing Caps
The best method for apply- ing torque is to tighten the bolts in passes. That is to say if the required torque is 100 ft-lbs for a 348/409 main cap, the first torque setting should be at about 30 ft-lbs. After double checking all the main bolts (or nuts, if studs are used) the next setting should be close to 60 ft-lbs. The next setting, after double check- ing the second pass, is the final one—in this case at 100 ft-lbs—with another round of double-checking. Smart builders go over each bolt or nut twice to confirm the torque set- ting is correct. Another one of those double- and triple-checks is to rotate the crankshaft after all torquing, ensuring no restrictions and espe- cially noting the clearances between the crankshaft and block. The same should be done when the rods go into the engine and are bolted to the crankshaft. If any clearance problems occur, the problem must be resolved before assembly can continue. If grinding on the block is needed for more crankshaft or connecting rod clearance, the block must be washed thoroughly again and the prep/build sequence restarted.
Rear Seal and Crankshaft Installation
Part of dropping the crank- shaft in is installing the rear main seal. Again, methods vary depend- ing on the equipment used. For more stock builds, an original-style rope seal can been replaced with two-piece poly seals available at many 348/409 suppliers. Of the four pieces that make up the oil pan gas- ket, it is best to install only the rear main seal at the time of installing the crankshaft. The rest of the oil pan gaskets can be installed when the oil pan goes on after all the rotating assembly parts are installed. Putting in the rear main seal before the others gives the seal in its bed of sealant time to set up in the groove of the main cap. A good cleanup of any excess silicone sealer can be done with a rag and screwdriver. Covering the screwdriver with the rag, the excess sealer can be scooped out of the groove and off the face of the journal. Spending a little more time here prevents leaks and makes for an easier cleanup.
Check for Binding
It’s a good idea to rotate the crankshaft to check for any binding or noticeable drag.
The next step in the build depends on the type of build. If it is a race engine, the cam may go in before the crankshaft as the extra room in the middle of the block is more accessi- ble when the pistons are not in place. That room allows the builder to hand walk the cam into place, as opposed to using a cam-install tool. Cam installation tools work fine, but are designed for a blind installation and care must be taken to ensure the cam or its bearing faces are not nicked or damaged while being installed. Hav- ing room to use fingers or tools to guide the cam in from the bottom of the block is desired because the cam and bearings have less of a chance of being damaged.
At this point, if both the crank- shaft and cam are installed, it is best to put the timing chain set on to keep the cam from moving fore and aft and risking damage. If the cam is not installed, it might be a good time to do so as turning the rotating assembly is more difficult when all the rods and pistons are in place.
When installing a cam, the man- ufacturer usually supplies a lube for the lobes. After a liberal application of the lube, the cam can be care- fully installed as noted earlier. With the cam in place, the timing chain is next, but not before making sure the crankshaft key is installed into the snout of the crank. This key aligns the gear on the crank and keeps it from changing its location. When using performance parts, sometimes a timing gear set has more than one keyway. Any other keyways are used for advancing or retarding the timing, so it’s best to ensure the right one has been cho- sen. Installing the timing gear and chain is best done by following the manufacturer’s directions. With the timing gear pressed onto the crank- shaft’s snout, the cam’s timing gear (the bigger of the two) is bolted to the cam. Note the use of any locat- ing pin for correct alignment. The cam gear and the chain should go on at the same time as once the gears are in their proper location, the chain is impossible to install over them.
Install Cam Bolts
The three bolts for the cam gear are to be torqued to the manufactur- er’s specs. In the case of a stock tim- ing gear, the 5/16-inch bolt should be torqued to 20 ft-lbs. At this time, giving the crankshaft another series of turns is a good idea for check- ing any resistance or bind. Like the crankshaft to the rods and pistons, the cam is the foundation to the valvetrain and needs to rotate with- out any problems. The timing chain cover is installed later. If the cam is to be degreed, installing the timing chain must wait until at least the number-1 piston is in place.
Install Pistons, Rings and Rods
With the crankshaft and cam joined by the timing chain, fill that block with some pistons and con- necting rods. By now, the pistons, rings, and rods have been assem- bled and laid out on a bench, ready to install. And like the crankshaft, the rod bearing clearance should be checked and rechecked.
Consistency should be used when installing the pistons. Begin with positioning the crankshaft to receive the rods and lower the rods into the bore, being careful to not scratch the bore surfaces and then also being careful not to damage the bearing surfaces of the rod journal, securing the rod to the crankshaft. Once properly fitted to the crank- shaft, torque the rod bolts to the manufacturer’s specs.
This is a good time to keep up with another good practice—con- stantly inspecting parts as they go together in the engine, or any other assembly for that matter. Inspection should continue through the build and even into start up and break- in. Vigilance catches small problems and can keep them from growing.
To rotate the crankshaft, a way of turning the snout of the crankshaft is needed. Some prefer to use the bolt from the balancer, while others use a tool specifically designed for such work. Either way, a long-handled wrench is needed as a number of full rotations of the crankshaft are done during the course of assembling the engine. Another tip is to always turn the crankshaft the way it turns in operation. For W engines, that direc- tion is clockwise (looking at the front of the engine).
One advantage of building a stock or relatively stock W is not always having to use a ring com- pressor. With the off-center cylinder overbore(s) and oval shape of the bores at the deck, the rings are able to slip right into the bore without much compression. Typically, pistons are pushed down the bores with a ham- mer handle by tapping the rubber covered or wood handle on the top of the pistons. Some builders prefer to protect the bores from scratches caused by rod end bolts and use cov- ers on them. Others just use their hands to control the movement of the rod inside the bore as the piston is pushed in from the top. The key here is one at a time, and to make sure the rod bolts and caps are in place and holding the rod bearings before mov- ing on to the next cylinder. That’s because each cylinder must have the crankshaft lined up to accept the rod end with the best alignment.
Almost all builders squirt a sup- ply of oil on the rings and pistons to ensure minimal metal-to-metal con- tact, thus avoiding damage to the bores and the finish on the piston rings. The same holds true for the rod bearings. As each rod and piston is installed and located correctly in the proper cylinder, the rod end cap can be torque to 40 ft-lbs. Race or high- performance rods may higher torque settings so it is best to use the manu- facturer’s specifications. The proce- dure is repeated for all eight pistons with more oil applied to the bores as the assembly is rotated for align- ment. One more look to ensure the right pistons are in the right bores and are facing the right way is a good practice in a 348 or 409.
Degree the Camshaft
To just about wrap up the short- block assembly, it may be time to degree the cam. This is usually the case for a high-performance engine than a stock engine. For stock engines, the simple aligning of the marks on the timing gears is suf- ficient. For cam degreeing, two dial indicators are needed. One indica- tor is used on the number-1 intake lifter, and the other on top of the number-1 piston. Many builders do this with only the number-1 piston installed, as it is easier to rotate the crank. A degree wheel is attached to the crankshaft and an indicator is set up to point to the numbers on the wheel. It is best to run it through the cycle a few times to make sure a true reading is consistent.
Ensure the lifters for the num- ber-1 piston indicate closed valves. Rotate the crankshaft to move the number-1 piston to the top dead cen- ter (TDC) position or the farthest the piston moves upward. Check that the pointer on the degree wheel reads zero. Rotate the crankshaft again until the dial indicator on the num- ber-1 piston is at .250 inch. Verify the degree indicated by the pointer and write that number down as the after top dead center (ATDC) read- ing. Rotate the crankshaft again through its cycle. When the piston moves toward TDC, stop when the dial indicator reads .250 inch again. This is called before top dead center (BTDC). Now check the degree wheel to ensure the number is the same as the first reading of ATDC. Using the two measurements, they are the same if the degree wheel is set at TDC. Rotate the crankshaft to TDC and install the timing chain. If those measurements don’t match, the degree wheel may not be set at TDC. Adjust it and repeat the process until the measurements are the same.
The numbers desired are deter- mined by the builder and the cam specs selected. When satisfied with the results, the builder takes off all the equipment and continues to install the rest of the pistons. With all the rods and pistons in place and properly torqued, the next step is to install the timing chain cover.
Installing the timing chain cover is simple, and the key is to use the factory or factory-style gasket cor- rectly to avoid leaks. Like valve cov- ers, many builders silicone the gasket to the part that is being attached. Then, the 10 bolts used can be wrench-tightened to complete instal- lation. Note that there is more than one style of timing cover used on W engines not including any one or two piece styles of covers for perfor- mance engines. Chevrolet only used one timing cover throughout the run of Ws, but there was a difference in where the timing tab was mounted. The tab locations were different depending on the different sizes of harmonic balancer used for low- and high-performance models. Once the timing chain cover, complete with its seal in the cover is in place, the har- monic balancer can be installed.
Installing a harmonic balancer is all about getting it on the snout of the crankshaft straight and with no damage to either piece. The balancer does what its name implies, damp- ening the harmonic vibrations from not only the crankshaft but the entire rotating assembly. It is important to keep those forces to a minimum as they can develop cracks, loosen fas- teners, and fatigue parts—all lead- ing contributors to engine failures. The harmonic balancer can be easily installed with a tool made just for installation by pressing it onto the snout of the crankshaft. Using the hole in the end of the snout that locks down the balancer when it’s on, the balancer is slowly moved into posi- tion on the crankshaft’s snout until it reaches its proper location. The tool is then removed and the bolt, lock washer, and large flat washer are attached to keep the balancer on the snout of the crankshaft.
Oil Pump, Windage Tray and Oil Pan
Completion of the short block also gives the builder the option to also wrap up the bottom end by installing the oil pump and pan. The pump is usually a separate assembly from the tube, pickup, and screen. Since it is important to keep the sup- ply of oil consistent and free from sucking air (cavitation), the tube should be affixed to the pump in a mostly permanent way. From the factory, the tube is pressed into the pump, which is usually sufficient. The same holds true for the pickup and screen to complete the assembly.An old racer’s trick, when using a stock tube, pickup, and screen, is to braze or tack-weld the parts to each other. Racing W engines usu- ally don’t use the stock parts, instead opting for hard core racing products that have a higher degree of reliabil- ity built in.
The oil pump is bolted to the rear main cap and should be torqued to 50 ft-lbs for stock applications. High- performance builds may have differ- ent settings, as well as a remote oil pump as in a dry sump build. Typi- cal oil pan gaskets can be up to four pieces including the front and rear main seals. Again, here is a good time to make sure of a proper fit to avoid leaks in the future. There are two different oil pans from Chevrolet for W engines: 348 and 409. While they bolt up to the same pattern on the bottom of the block, they differ in how they widen out to provide more crankshaft rotating clearance. Both sizes use 20 bolts to attach to the block. Aftermarket pans attach the same way on a stock block.
One more step is done at this time for many builders who want a little cheap insurance. For openings such as the water pump intakes into the block or even the oil filter boss, it’s the right time to cover any such holes to prevent damage from foreign objects entering them and getting further into the engine. As the build progresses, more openings, such as the exhaust ports or distributor hole, are covered for the same reasons. This is especially true if the build is taking place over a number of days.
If any other head components are used in the build, now is the time to install them. This may include pushrod guides or screw-in studs. The rest of the valvetrain is installed after the head is bolted on.
Many builders assemble all components before final assembly begins. In the case of the heads, it can go either way. Some builders stop when the short block is done and assemble the heads. Most have their heads complete and ready to bolt on at this point. From a mechanical viewpoint, it makes no difference. But having the rods and pistons fully assembled is mandatory for building the short block.
There is a specific pattern for tightening down W-engine heads. Much like the main caps, a set of passes should be used rather than torquing them down all at once. As the ultimate torque setting for the head is 65 ft-lbs, the first pass should be 20 or 25 ft-lbs, the second one 45 ft-lbs, and the last 65 ft-lbs. The first bolt to tighten is the most center one. This sets the head onto the block and gasket without damaging the gasket, thus keeping it intact and working properly. To also set the head and gasket, the second head bolt/stud
is located just below the first. From there, the tightening pattern fans outward, distributing the load evenly across the head and deck.
There are 18 bolts for each W head. Why so many? At the time and for quite a while afterward, W engines had the biggest bores of any Chevy engine. Big bores mean big inches and that most definitely means big power. Basically, the function of a head bolt for any engine is to hold down the head over the cylinder or combustion chamber. To hold the heads to the block and keep them from suffering from any heat or power distortion, 6 of those 18 bolts go around the bore of the cylinders. As the cylinders are so close together, some of those bolt holes are used for two cylinders. When looking at the bolt pattern of a W engine, one can easily see how all those six bolts circle the bores.
With 18 bolts for each head, smart builders count them out before and double check them afterward. And as there are two lengths of head bolts for W engines, separating the two different bolts is suggested. If racing or other aftermarket heads are used, follow the suggested torque specs with the same tightening sequence for best results. Again, make sure the correct-length bolt is in the correct hole. Visual checking is the easiest way. A bolt that is too short drops into the hole all the way. Those that are too long stand out noticeably.
Repeat the procedure for the remaining head and the heads are done. It is at this point many build- ers choose to cover up the exhaust ports so no debris enters. Those ports are open until the exhaust manifolds or headers are mounted to the heads. Remember, anything that can find its way into the area adjacent to the valves can also fall into the combustion chamber and cause serious damage.
Keep in mind, 348 and 409 push- rods come in two lengths. The intake pushrods for both engines are shorter than the exhaust pushrods.
Cylinder Head Installation
With the completion of the short-block assembly, it’s on to the mounting the heads. The first step to mounting heads is to place the head gasket on the deck. Buy the best-possible gaskets for the build, as replacing a lesser quality one later on will be labor and time consuming. Most head gaskets have the word “TOP” stamped into them to indicate which side of the gasket should face up. For stock builds, locating pins in the block keeps the gasket and head in place. In performance builds, those pins may have been removed for deck machining and must be replaced. For fastening the heads to the block, bolts or studs are used. Stock builds use bolts while racing engines can use studs and installing them is done the same way as install- ing main-bearing caps.
After the studs are in place, the head gaskets are placed on the studs and deck of the block. W heads are universal in fit; there is no left and right side head. Getting a good grip on the heads and taking a balanced stance above the block is the best physical way to install heads, iron or otherwise. Lowering the head down onto the deck and finding those locating pins on the block is the way for stock heads. Sliding the head gently over the studs is the perfor- mance way, making sure to not dam- age the threads of the studs. When using stock heads, the next step is to start the head bolts. For more race- oriented builds, the washers and nuts for the studs are applied.
Keep in mind W-engine heads use two different lengths of bolts or studs for the heads and the correct- length bolt is critical. Also, some of the bolts/studs go into open holes and others into blind holes. Open holes often go right into water or oil passages, so sealing is critical. Blind holes, or holes that do not have an opening at the end, are just as impor- tant. Blind holes need to be free of anything that can block the bolt or stud from fastening correctly or, worse yet, giving a false torque read- ing. Blind holes also cause problems when filled with oil, solvent, or other liquids that cause the bolt or stud to not tighten. Builders often use a sealer on any open hole bolts and only oil on blind holes. Know the difference ahead of time and where they are and one less mistake will be made.
Here are some tips for proper installation of head gaskets:
•Cleaning. The most important operation of regasketing your engine is thorough cleaning of the cylinder head, block, bolts, and bolt holes. A dirty bolt can throw off torque readings by as much as 20 ft-lbs.
•Watch bolt lengths. Head bolts on some engines vary in length and it is important that these bolts be replaced in their original location.
•Head bolts that enter the water jacket of the engine should have sealer applied to the threads. Bolts that enter blind holes should be lightly oiled.
•Use a torque wrench! Uneven torque causes block distortion and head warpage allowing coolant leak and power loss. The basic tightening procedure is to snug-up fasteners in stages. Com- plete the last stage with final torque.
Installing Valvetrain Parts
The pushrods, while appearing to be a simple piece, must be the cor- rect length for the valvetrain or the other pieces will be over- and under- extended. When laying out the parts for assembly, checking the length of the pushrods is another critical mea- surement.
There is a dedicated tool for just such work and it works like a turn- buckle. It is adjustable in length and indicates the proper length to match the manufacturer’s specs. It works by inserting the longer part into the head and then into the lifter. The shorter end is located higher (near the rocker) and can be adjusted to give the rocker the correct angle needed. Once the proper length is determined, the correct pushrods can be used.
With the heads on and fully torqued, it is time to turn to the val- vetrain and its components. First, the lifters need to be installed into their bores, making sure to give them a lib- eral coating of oil or assembly lube. This is a good time to remember that any moving part that is included in the engine’s oiling system should not be installed without oil to prime and protect it. Oil travels through the lifters, so giving them a good sup- ply is suggested to prevent starvation during initial startup. Yes, if an oil priming tool is used prior to the first firing up, there should be oil in the system. But a little advanced think- ing is always recommended because for the first few engine revolutions, there will be no oil in place.
With all 16 of the oiled lifters in place, the next valvetrain parts to be added to the heads can be the push- rods. Keep in mind, 348 and 409 intake pushrods are shorter than the exhaust pushrods. The pushrods are simply and gently dropped through the holes in the heads to line up in the center of the lifters. Again, 16 of them are needed, and another old engine builder’s trick is to roll each one on a piece of glass to check for straightness. A bent pushrod greatly affects the timing of that cylinder and will likely continue to bend.
The next part of the valvetrain is the rockers and here is where there is a bigger separation between stock and performance. For stock engines, the simple stamped-steel Chevy rockers and ball mounts are put over the rocker studs and a nut follows to tighten them to eventually the right valve adjustment. For now, each one is only hand tightened, making sure the pushrod is in its proper location in the pushrod pocket of the rocker and in the center of the lifter. The rocker also needs to be in the cor- rect position over the end of the valvestem and the spring keeper. The favorite way to do this is to gently jiggle the rocker into position with one hand as the nut is snugged with the other. The hand tightening is for keeping things in place until it’s time for valve adjustment.
For more high-performance builds, the use of stud girdles and roller rockers may be involved. Some stud girdles attach to the block with fasteners while others clamp around the mounts of the studs. These are used in higher RPM engines and are almost always accompanied by roller rockers. Roller rockers are also built for higher RPM and use needle bearings to safely move their parts between the pushrods and valves. Like the stamped versions, they are hand tightened during a build and adjusted with the valves later.
With the valvetrain complete, it’s time for the intake manifold. An intake typically requires four gasket- ing components—a simple seal for the front and rear of the block, and a pair of more-developed gaskets that sit between the heads and intake mani- fold. Experienced builders often make sure the gaskets between the heads and intake are matched to the ports. Any overlap of the gasket in that area can reduce the flow of fuel to the com- bustion chamber, robbing horsepower (see Chapter 6). The four pieces of the intake gasket assembly are usually two different types. The intake-side gaskets are usually stamped metal or composite. The gaskets that go on the front and rear of the block under the intake are more like seals. The front and rear gaskets are usually sealed to the block while a less-permanent product holds the intake-side gaskets in place by being tacky.
With all four gasket pieces in place, the object is to lower the intake straight into place on the block without disturbing the gaskets and their chemicals. The trick is to remember not to move the intake into the correct position other than raising or lowering it into place. Any fore, aft, or sideways move- ment disrupts the gaskets causing a less-than-perfect seal. Practicing by using a dry block and intake is one way to learn how to drop the intake in place perfectly.
With the intake in its proper place, the 12 intake bolts can be started. Like the heads, the intake has a correct sequence to tighten- ing as well as a torque setting. The setting for torque is 30 ft-lbs and the sequence, like the heads, starts with the center fasteners. As the bolts appear to be in sets of pairs, the sequence starts with the four bolts in the middle of the intake mani- fold. Two bolts are on each side of the intake and should be tightened much like those on a wheel, in a crisscross pattern. From there, work outward from the center until all the bolts are tight. Care should be taken when using an aluminum intake or heads as threads can be ripped out if over tightened.
You may have noticed that I did not describe installing the valve covers until after the intake was mounted. Most builders prefer to wait to install the valve covers until the valves have had their primary adjustment. That way, they don’t have to be taken off for adjustments. Another reason for leaving them off is they won’t get in the way when installing the intake manifold.
Many builders affix the gaskets to the valve covers and just lay them in place at this stage of the build. Like the safety covers over openings, laying the valve covers in place can keep out containments and foreign objects that can cause damage.
Bolting the head on with a head gasket is a great way to check valve- to-piston clearance. Slowly cycle the crankshaft and feel for any vibra- tions. Another way to check this is to use a gauge material much like the one used for main and rod jour- nal clearance. Once the engine has cycled more than a few times with-out any contact or the gauge mate- rial indicates meeting the piston manufacturer’s specs, the head can be bolted on for final assembly.
Intake and Ignition
For most applications, the assem- bly of the long block is now com- plete. What is added from this point forward depends on how the engine is installed and how much work takes place with the engine in the vehicle. Ancillary items such as water pump, pulleys, fan, belts, pumps for air con- ditioning or steering, distributor, induction, and exhaust manifolds or headers are usually arbitrary as they sometimes get in the way or can be damaged during an installation. That damage can be from the sling or chains used to lift the engine or any fixture used to hold the engine while installing it.
Bolting it to the desired transmis- sion is also a dealer’s choice affair, and some prefer to drop the two in together, and others prefer to install the transmission separately. Most people find that installing the engine with the transmission is much easier in a stock-type application. Along those lines, race vehicles are often set up to receive an engine by itself, usu- ally with the bellhousing and clutch already in place. The transmission is installed later via quick-disconnect, racing equipment.
Regardless of how the install goes from here, map out a good plan for firing up your W engine that includes a fire extinguisher, plenty of rags, and a number of well- thought-out checklists. If it is to be your first time at doing so, contact a friend who has been there before as experience saves time, money, and mistakes. And good luck.
Written by John Carollo and Posted with Permission of CarTechBooks