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Engine assembly: Completing the assembly

Completing an engine assembly carburetor installation

In our last segment, we buttoned up the top end of the engine (cylinder heads). Essentially, we constructed a complete "long block." This time around, we'll complete the engine assembly with rocker installation, intake, carburetor and so on. By the way, the homestretch is very simple. There are a few special tools you'll need, but there's nothing here that's extravagant. And like we've stated in the past, if you can tighten bolts and know how to operate a torque wrench, it's pretty much easy street. Take a look.

Lifter installation
If you can apply lubricant to the body of a lifter, you can install it. Essentially, you should apply motor oil (liberally) to the lifters. Slip the lifters into their respective bores. If the engine is equipped with roller tappets, install the lifter pairs with the associated connecting links. Today, most connecting links are permanently attached to the lifter body, and in most cases the lifters are positioned with the links facing the center of the lifter valley in the cylinder block.

Pushrod installation
In most cases, the pushrods simply drop into a guide plate of some sort in the cylinder head, with the lower end fitting directly into the cup of the lifter. The top end fits into the matching rocker arm. It's a simple install. 

On the other hand, if the engine is modified with items such as a small base circle camshaft, non-stock cylinder heads, non-stock rocker arm mounting positions, severely milled deck (or head) surfaces, longer-than-stock valves, the use of valve lash caps and other factors, then you may need to establish the correct pushrod length.

Even in a normal situation (where the geometry hasn't changed due to the factors mentioned above), the tip of the rocker arm tends to sweep across the tip of the valve. If the geometry has changed and the pushrod length is not optimized, the amount of movement the rocker sees across the valve tip is considerable.

To check the geometry and to establish correct pushrod length, you'll need a checking pushrod. There are several available. We have one from Crane Cams. First, turn the engine over until the rocker arm/pushrod combination you're checking is on the base circle of the cam (both valve closed). With the rocker removed, coat the tip of the valve with a black felt marker. Reinstall the rocker arm.

Move the rocker so that a mark becomes visible on the tip of the valve. If the geometry is correct (and the pushrod length is correct) then the mark you see on the valve tip (made possible by rubbing away the felt marker "paint job" you made) should be located approximately one-third of the way across the tip, on the inboard side (toward the intake manifold). If the mark is in the center of the valve tip or if it is closer to the exhaust (header) side of the valve tip, the pushrod is too long. If the mark is closer than one-third the distance to the intake manifold, the pushrod is too short.

To establish the right pushrod length, you'll need the adjustable "checking" pushrods mentioned previously. Install the checking pushrod in place of the conventional model. The adjustment feature allows you to lengthen or shorten the pushrod as necessary. Repeat the "paint the tip" and check the scrub mark with a longer or shorter pushrod length. It's a matter of trial and error (shortening or lengthening the adjustable pushrod) until you arrive at the length where the scrub line on the valve tip is correct. At this point, measure the adjustable pushrods so you can determine the optimum length. You can now order the right pushrods (length) for your application. Once they arrive from the manufacturer, it's a good idea to double-check the length (and the geometry) before slipping them into place.

Rocker arm installation
Conventional stud mount rocker arms simply install over the rocker studs and are most often held in place by way of a lock nut. When installing conventional rockers, you should double-check the fulcrum. Most roller rockers are designed with a machined flat that mates with the rocker adjuster nut. Be sure the machined flat is correctly oriented. Apply a small amount of engine assembly lube to the pushrod tip. The engine will have to be rotated through a complete cycle so that all of the rockers are installed while the cam is on the base circle. All that remains is to install the rocker and to set the valve lash. (Refer to your cam manufacturer specification card for the valve lash figure and to the engine manufacturer specifications for the valve lash procedure.) 

When it comes to shaft mount rockers, the installation isn't much more difficult. With pushrod length verified, torque the stand bolts to specifications. Next, apply assembly lube to the pushrod tip and bolt the rocker to the rocker stand. Torque the rocker shaft bolts to specifications. Keep in mind the engine has to be rotated through the cycle so that the rockers are installed with the cam on the base circle. Set the lash, and you're done.

Intake manifold installation
There's no question an intake manifold is an important piece of the high performance puzzle. If installed improperly, they can definitely have a negative effect on performance. The best plan is to test-fit the intake manifold to ensure that it will actually work on your engine (things like cylinder head and block milling have an effect on manifold fit). Here's how it's done. 

Place a dry intake gasket on each side of the heads and lower the manifold in place. In some applications, you use a light to peer down the port to check alignment. In other cases, you can feel the fit by using a piece of wire to probe the port alignment by way of the plenum (a stiff piece of mechanic's wire or a coat hanger will work). You should also check the end gaps at the front and rear of the manifold where the intake attaches to the block valley. There must also be a small gap at the front and the rear.

Remove the intake and carefully clean the gasket mating surfaces with brake cleaner (or solvent). Apply a bead of RTV silicone sealer along both of the ends of the lifter valley (the front and rear of the engine). Next, install the intake manifold gaskets on the cylinder heads. A small amount of gasket adhesive can be used to ensure the gaskets do not move as the intake is installed. Carefully lower the intake in place, setting it straight down the valley on the respective gaskets. Do not attempt to slide the manifold from side to side or from front to back. This can create gasket misalignment. By the way, this sounds more difficult than it really is. You simply have to line up the bolt holes in the intake with the threaded holes in the cylinder heads.

Hand thread all of the intake bolts into the cylinder heads. Much like the cylinder heads, there's almost always a specific torque sequence used to tighten intake bolts. Typically it begins from the center and works outward. Consult a factory manual for specs on your specific powerplant. Much like the cylinder head torque sequence, begin the process with one-third (approximately) of the specified torque. Repeat the torque sequence three times (this is often necessary in order to get the manifold gaskets to compress fully).

Oil pump installation
Before installing the oil pump, the driveshaft must be installed. With the engine upside down (crankshaft facing up), it simply drops into place. You can now install the pump. Some pumps such as the big Titan model in our photos use a stud as a fastener. The stud is first installed on the rear main cap, followed by the pump. Then the nut (or bolt, depending upon your application) is torqued to the factory specification.

Oil pan installation
If a windage tray is used in your particular application, there's a good chance it bolts onto special studded main cap bolts (see the accompanying photos for a closer look). Here, it's simply a matter of dropping the windage tray over the studded main cap bolts and tightening the locknuts. Torque to factory specifications. 

Next, apply a thin bead of RTV silicone sealer to the oil pan flange on the cylinder block. If equipped with a multiple-piece gasket (common on earlier engines) install the neoprene end seals first, then install the side pan rail gaskets. Apply another thin bead of RTV silicone to the top of the end seals and pan rail gaskets. Alternatively, if the oil pan gasket is a one-piece affair, simply drop it into place. Install the oil pan and tighten the bolts evenly. Double-check the torque specification in your factory manual.

Harmonic damper installation
The harmonic damper (often called a "balancer") is engineered to fit tightly onto the crankshaft. Installing it or removing it can prove troublesome. To ensure you don't have excessive grief, coat the crankshaft snout with anti-seize compound. 

The other part of the puzzle is the actual installation. You can't hammer it on. And never use a bolt to install the balancer or you may pull or damage the threads in the crankshaft snout. You have to pull it on. What you'll need is a special tool for the job. We have two of them: One is a vintage GM Kent-Moore tool while the other is from the folks from B & B. In either case, they work in the same way. The body of the tool is a large "stud," and it is screwed into the threads in the crankshaft snout. The damper is slid over the tool body. Next, a special flange with ball bearings is placed against the body of the damper.

With our tools, a five-eighth-inch wrench is used to keep the stud and the crankshaft from turning. A large 1 3/8 nut is used to press the balancer over the crankshaft snout. We don't have a wrench that large, so we use an adjustable crescent wrench for the job (which is perfectly acceptable). By turning the big nut, the damper is slowly and evenly pulled onto the crankshaft. Once it seats against the crankshaft, install the harmonic balancer bolt and washer. Torque the bolt to the crankshaft manufacturer's specifications.

Distributor installation
Before the distributor can be installed, the crankshaft must be rotated until the #1 cylinder begins the compression stroke. This can be determined by watching the valves (rockers) on the #1 cylinder. If both valves are closed, or alternatively if you feel compression escaping from the #1 spark plug hole, slowly rotate the crankshaft until the timing marks on the damper show the correct initial timing (base timing setting). 

Next, install a gasket over the end of the distributor gear, and install the distributor shaft into the distributor hole. Select one tower on the distributor cap that will have the #1 spark plug wire connected (usually one that faces forward toward the front of the engine). As the distributor gear meshes with the camshaft gear, you'll find there will be several engagements that work. Pick one where the distributor rotor points directly at the #1 tower of the distributor cap. Simultaneously, you have to ensure that the oil pump shaft is fully engaged. If it isn't, the distributor won't engage fully (and in most cases, the shaft collar won’t drop to the base of the intake manifold). The bottom line: It might take several tries to get the pair of gears and the oil pump shaft to all engage properly. In some cases, a large screwdriver can be used to turn the distributor shaft slightly so that it meshes properly with the distributor.

Install the distributor hold-down clamp, but allow the hold-down bolt to be slightly loose. This will let you advance or retard the spark (ignition) timing as necessary (set after the engine is running). Be sure to follow the manufacturer's recommended procedure for setting the initial spark timing.

Carburetor installation
Carburetor installation is very simple. Install a set of appropriate carburetor studs into the intake manifold (usually a double nut process will be necessary to install the studs). Slip a carburetor base gasket over the studs. Drop the carburetor in place and gently tighten the nuts on the carburetor studs. Usually a crisscross pattern is used to tighten the fasteners. Just don't overdo it. It's easy to crack a carburetor base plate by being too zealous with the fastener torque. 

Add the oil pan of your choice (oil pans are typically configured for both the engine and the vehicle chassis). Install your favorite valve covers (ensuring they have sufficient height to clear the valvetrain and an air cleaner of your choice. Aside from a few accessories (vacuum lines, PCV valve, breathers), you're done!

Tools used

  • Adjustable pushrod
  • Oil pump primer
  • Wire crimper
  • Crankshaft installation tool

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Lifters should be lubed prior to installation. It doesn't matter if they're mechanical rollers (such as these Crane models shown here) or very simple flat tappet models. A good coat of 30W oil is all that's necessary.


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Rocker arm installation isn't difficult, particularly with stud mount rockers such as these extruded aluminum Crane roller versions. The rocker simply slides over the rocker stud; however, the fulcrum must be correctly oriented. See the next photo for more information.


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Note the flat on the fulcrum. That's where the rocker adjuster (commonly called a "Polylock") seats on. It must be oriented this way.


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Before any rocker can be completely installed, it's a good idea to check the pushrod length. We use an adjustable pushrod tool to determine the length. Once the appropriate pushrod length is determined, you simply measure the adjustable pushrod and order a set made to length.


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To check rocker geometry (and to determine pushrod length), first coat the valve stem tip with a felt marker as shown here.


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With the checking pushrod in place (camshaft on the base circle), install a rocker. Next, move the rocker from side to side while pushing down. The idea is to make a witness mark on the top of the valve stem.


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Remove the rocker and examine the mark. As pointed out in the text, you want the witness mark to be approximately one-third of the way up (toward the camshaft).


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Once you've checked the pushrod length (if necessary, wait until your new pushrods have arrived), you can complete the rocker arm install. In this photo, the rocker stand is torqued to specification.


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Here, the pushrod is installed and our shaft rocker is bolted in place. It has a pair of torx fasteners on each end. Tighten with a ratchet and then torque to specification.


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Where conventional rockers have the lash set at the polylock (on the stud/rocker fulcrum), Jesel shaft rockers such as these have the lash set at the pushrod cup. In either case, you still need to use a feeler gauge between the valve tip and roller rocker tip.


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Oil pump installation isn't difficult. Either a stud or a bolt is used to hold it in place. In this photo, the pump stud is installed. In the next photo, the pump is slid into place over the stud (and engaging the dowels on the main cap). Be sure to include the pump driveshaft! In some cases, it can only be installed one way (from the bottom up). Finally, the nut is torqued to specs.


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Some engines make use of bolt-on windage trays. Others don't. If it has a bolt-in windage tray, there's a good chance it uses some sort of extended main cap fastener such as these. They take the place of the center main cap bolts. The extensions on the end allow a windage tray to be installed over the caps.


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We have several different harmonic damper installation tools in our toolbox. This one is from the folks at B & B Performance. The tool physically pulls the damper onto the crankshaft without damaging the crankshaft (or the harmonic damper).


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To use the damper tool, the small end is screwed into the crankshaft. The damper is installed over the tool (and engaged in keyway in the crank snout). The special bearing included with the tool is installed between the damper and the large tool nut. A large adjustable wrench is used to tighten the nut while the crank is held steady by the five-eighth-inch box end wrench. Tightening the nut simply draws the damper into place.


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A gasket can be used on the intake manifold end seals, but a bead of silicone is often used instead. Run a bead of RTV over the manifold mounting surfaces on the cylinder block valley (front and rear).


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Carefully drop the intake manifold in place and install the fasteners. The text notes the torque sequence, but basically you start in the center and work your way out.


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To install the distributor, install the base gasket (or shims) first. Then, drop the distributor into place. It might take several tries to get the orientation right (and simultaneously to engage the oil pump driveshaft).


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Carb studs are installed in the top of the intake plenum, followed by a carburetor base gasket. Then you can install the carburetor.


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The oil pan installation is rather simple: Run a light bead of RTV silicone over the gasket mounting surfaces of both the oil pan and the block. Sandwich the gasket(s) between them. Install the hardware, torque to specs and you're done.