Final assembly is the most important step of any rebuild. The assembly process oftentimes varies slightly from person to person. There’s no issue with that as long as the technique produces an engine that operates consistently and reliably for long periods.
Depending upon the year, your Pontiac V-8 may contain unique components that must be installed in a specific manner or require a specific technique. I highly recommend referring to a Pontiac Service Manual for your year of engine, so you can learn the rebuild techniques that may be specific to your engine. I also recommend consulting with the manufacturers or a Pontiac vendor for proper installation information and torque specifications for any aftermarket components being used.
This Tech Tip is From the Full Book, HOW TO REBUILD PONTIAC V-8S. For a comprehensive guide on this entire subject you can visit this link:
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A careful, methodical approach is the safest way to be sure that your engine rebuild is successful. Plan to check and recheck your work often, and don’t be afraid to call the experts if you have questions along the way.
There are a few areas of every rebuild that I feel are very important. Many of the tools listed in Chapter 2 can each determine a successful rebuild versus one that can end in failure. In addition, but rarely considered by those less experienced, cleanliness, assembly lubricants, and sealers should be considered a critical part of every rebuild. Many hobbyists are unfamiliar with how important each is and how to properly use them.
An engine consists of many precisely machined and polished surfaces. The components operate at very close tolerances with a thin film of lubrication between them to reduce friction. Any dirt or debris within the engine can compromise that lubrication film, causing irreparable damage to the components that you likely spent a healthy sum having machined or purchasing new. Any damage could require additional machining or polishing, or even buying a new replacement.
I cannot stress enough that every precaution to prevent any type of contamination must be taken during the assembly portion of any rebuild. If there is any question about the cleanliness of any engine component, even if it’s new and fresh out of the package, it’s best to blow it out with compressed air, thoroughly wash it with hot soapy water, or wipe it down with residuefree solvent and a lint-free cloth. You can never be too safe!
The engine assembly room or area of professional engine building shops is usually very clean and organized, and free from any substance or contaminant that could compromise a rebuild. Your garage or shop shouldn’t be much different. The area should be extremely clean—free of any dust or dirt that could be kicked up while walking around. The bench surface should be very clean. I sometimes lay down several layers of clean newspaper if I detect any visible contaminants on the bench surface. The tools required for assembly are also thoroughly cleaned with residue-free solvent and a lint-free cloth.
High-quality assembly lubricant is very thick and protects delicate surfaces with tight tolerances, such as the bearing and journal and a rear main seal, during assembly and initial startup. Heavier engine oil, such as a 30W break-in variety, is used to lubricate certain contact surfaces, including cylinder walls and piston rings.
Engine oil is also used to lubricate bolt threads. A couple drops directly onto the threads and under the bolt head is all that’s required for proper installation. Too much oil can produce an improper torque reading or worse, cause the bolt to hydraulic lock, possibly splitting the bolt hole while tightening the fastener to the suggested amount of torque.
If you’re using aftermarket fasteners like those from ARP, a specific thread lubricant may be required. ARP offers a moly-based paste that it recommends when tightening its fasteners. While 30W oil can also be used, a different amount of torque may be required. Check with your fastener manufacturer for more information on suggested lubricant and torque specifications.
I’ve had excellent success with Permatex-brand Ultra Black RTV silicone sealer. I suggest using it sparingly, however. Some hobbyists tend to use heavy applications to prevent leaks. I am more inclined to let the gasket do its job and use a very light coat of sealer to simply to hold the gasket in place or fill in pits or pores in the contact surfaces. It is readily available at your auto parts store, and your machinist can recommend one of a number of other highquality brands and types available.
Thread lock compound seals the bolts into threads and prevents them from vibrating loose. There are different “colors” available and the largest difference seems to be the method of removal. Red is very popular, but bolt removal requires a combination of heat and hand tools. Blue thread lock is the best choice for engine rebuilds since it is serviceremovable, which means that bolts are easily removed with hand tools for quick disassembly. I routinely use blue thread lock for certain bolts during engine rebuilds. A small drop is all that’s required to lubricate the threads and prevent a bolt from loosening.
Short Block Preparation
Step 1: Dress Camshaft Bearings (Professional Mechanic Tip)
The five bearings used to support the camshaft of a Pontiac V-8 are identical. Each has a more pronounced bevel on one end for easier installation. The beveled end points toward the rear of the engine and is intended to prevent galling while being driven into place. Use a file or small knife to “dress” the opposite end before installation. It removes any sharp edges that can score the camshaft journal.
Step 2: Install Camshaft Bearings (Special Tool)
Use a camshaft bearing installation tool to install the bearings in the block. Working from the front of the block, install the rear journal first. Drive each bearing into place without any lubrication. The bearing’s oil hole must be perfectly aligned with the feedhole located in the main saddle, or else oil starvation can occur. It’s generally not cost effective to purchase a camshaft bearing installation tool for a single rebuild. It may be best to let your machinist perform the task for you.
Step 3: Install Rear Cam Plug (Precision Measurement, Important!)
The block contains a machined step just rearward of the last cam bearing, which is intended to keep the rear plug from being driven in too far. Coat a steel plug with liquid sealer and drive it into place with an appropriately sized socket. The lip of the steel plug should be recessed approximately .300 inch below the surface. Driving the rear plug in too far can cause the cam to contact it during typical operation, sending metallic filings throughout your engine!
Step 4: Test Fit Camshaft
Install the camshaft to verify that the cam bearings are properly aligned and that sufficient rear cam-plug clearance exists. Lightly lubricate the camshaft journals with 30W oil and insert the camshaft into the cam tunnel. Make sure the camshaft is supported and the cam lobes don’t make harsh contact with the bearings because damage could result. The cam should rotate easily by hand with little effort and without any binding. Push the cam rearward and if its snout is recessed from the front surface of the block by any amount, then sufficient rear cam plug clearance is present. Carefully remove the cam to prevent damaging the new bearings and set it aside for installation a bit later.
Step 5: Install Block Freeze Plugs
Your machinist can supply you with a complete steel plug kit that includes every coolant and threaded-oil plug required for complete assembly. Otherwise complete plugs kits from Dorman or Melling are available at most local auto parts stores. Installation is very straightforward. Coat the block opening with high-quality liquid sealer. Using an appropriately sized socket, drive a steel plug into place until it is flush with the block. A bearing driver can also be used.
Step 6: Install Oil Gallery Plugs
A series of pressed and threaded pipe plugs seal the oil gallery front and rear. Coat the threaded plugs with liquid Teflon sealer and install them very tightly with a properly sized hex-head socket. Coat the pressed plugs up front with a liquid sealer and drive them into place with an appropriately sized drift. The plug lip should be about 1/8 inch below the surface, and the material around them is staked for optimal retention. A popular modification in high-performance applications is to tap the front oil gallery holes a nd install threaded plugs instead of pressed plugs, which prevents them from pushing out under high oil pressure conditions. It’s generally not required for stock-type rebuilds, however.
Step 7: Don’t Forget the Hidden Oil Plug! (Professional Mechanic Tip, Important!)
A threaded pipe plug seals the passenger-side oil galley. It installs from the rear of the block and is hidden under a pressed plug. It’s one that novice Pontiac builders often omit and it results in extremely low oil pressure. Fixing the issue requires a complete engine removal and partial disassembly, so you don’t want to forget to install the plug! A common modification is drilling a .030-inch hole into the “hidden” plug, which your machinist can perform for you on a lathe. It provides the camshaft and distributor gears with a constant jet of pressurized oil to reduce wear, especially when using a steel roller cam. The plug threads are coated with liquid Teflon sealer and tightened like the others with an appropriately sized hex-head or square-head socket and a 3/8- inch-drive ratchet. The pressed plug that covers it is simply driven into place with a small socket.
Rotating Assembly Installation Preparation
Step 1: Install Connecting Rod Bearings (Critical Inspection)
The connecting rod bearings should still be clean and in excellent condition even after the pre-assembly checks. The connecting rod body and cap saddles, along with the backs of the bearing shell, should be wiped completely clean of oil and debris. Even the smallest particles can compromise the bearing’s ability to carry its intended load, possibly leading to premature failure. There is usually no specific upper or lower rod bearing. Some brands or types may be different, however. Refer to the bearing instructions or consult with your machinist for verification. Without any lubrication, carefully press the bearings into place with extra attention to bearing tang alignment. They should fit snuggly in the rod and cap.
Step 2: Lubricate Connecting Rod Bearings
Both connecting rod bearing halves receive a generous amount of assembly lubricant on the journal surface. Assembly lube is thick enough that it should remain in place for several minutes without running or dripping.
Step 3: Organize Short Block Parts
Just before short-block assembly begins, I set out all of the associated components to be sure that everything is accounted for and that the main caps and piston-and-rod assemblies are arranged in an order that corresponds with cylinder location. I also install protective caps onto the connecting rod bolts, which cover the bolt threads, to protect the freshly machined block and crankshaft surfaces from scratches during piston install. You can also cut your own length of 1/2- inch-diameter rubber hose. I also had the machine shop thoroughly clean all of the engine’s nuts and bolts. I organized them for easy accessibility too.
Rear Main Seal Installation
Step 1: Insert Rear Seal
With the engine back on an engine stand, install the rear main seal. There are a number of suitable rear main seal options available on the aftermarket. The Graphtite seal from Best Gasket Company installs and functions much like an original asbestos rope seal. One half of the new rope seal is laid over the seal groove that’s machined into the block, while the other half is laid over the corresponding groove in the rear main cap.
Step 2: Pack the Seal
A number of tools can be used to pack a rope rear main seal into the groove, including a large socket, a length of steel pipe, or even a wooden rolling pin. Tightly pack the seal to a depth that replicates the approximate crankshaft diameter and into the antirotation holes that are drilled into the seal groove. I purchased a special tool that Kent-Moore produced a number of years ago. It was developed for Pontiac dealers and used by service department technicians for this very task.
Step 3: Install RTV Sealer
The newly formed rope seal halves are removed from the rear main seal groove in the block and main cap. Be sure to keep each orientated correctly. Apply a thin bead of RTV sealer onto the rope or into the grooves. A very small amount is needed. It serves only to prevent the rope seal from rotating at initial startup.
Step 4: Reinstall Formed Rope Seal
Each half of the formed rope seal is reinstalled into its respective groove and repacked. It isn’t uncommon to find a small amount of RTV sealer seeping around the seal while repacking it. Wipe it away with a clean towel.
Step 5: Cut Rope Seal
Best Gasket Company’s Graphtite rope seal kit includes a blade, a wooden finger guard, and a spacing template. Trim the excess ends of the rope seal in the block and main cap. The rope should be cut cleanly and without any frayed edges. The spacer leaves the rope seal protruding about .015 inch above the block surface, and it’s pressed flush by hand. When the main cap is installed, the rope ends compress slightly providing a positive seal.
Step 6: Apply RTV Sealer
The rope rear main seal installation is complete. Liberally coat it with assembly lube when installing the main bearings and lubricate the crankshaft just before setting it in place, which prevents damage during initial startup. During main cap installation apply a very thin layer of RTV sealer to the block and main cap mating surfaces that surround the rope seal. This seals any pores that could lead to potential leaks. However, do not apply any sealer directly to the rope ends.
Short Block Assembly
Step 1: Install Oil Dipstick Tube
The oil dipstick tube located in the block is typically removed during machining. The original can be reinstalled if the machinist was able to salvage it. Otherwise a replacement can be purchased from your favorite Pontiac vendor. Slide the tapered end of the dipstick tube though the opening in the block. Drive it through the block with a brass drift until it is completely flush with the block interior surface. Then rotate the block 180 degrees for camshaft installation.
Step 2: Install Camshaft Keyway
If your machinist didn’t supply a new 3/16- x 3/4-inch camshaft keyway, one is available from Dura-Bond (number AK-002-P), which can be sourced from a local parts store. Place the camshaft on a soft, solid surface and install the keyway into the groove located in the front snout. Some hobbyists use a large pair of pliers or a vice to squeeze the key into place. I prefer gently tapping it in with a small brass hammer. No matter the method, use caution to prevent damage to the cam journal surface.
Step 3: Install Camshaft
Lubricate the camshaft bearing journals with 30W oil, and liberally coat the distributor gear with assembly lube. Cover the lobes with the camshaft manufacturer’s recommended lubricant, which is specifically designed for breakin. In this instance, Comp Cams recommends simple assembly lube for its hydraulic roller unit, but a flat-tappet camshaft may require a thicker substance or paste, which the camshaft manufacturer should supply.
Step 4: Install Main Bearings(Critical Inspection)
Like the connecting rod bearings, the main bearings should still be in excellent condition after the pre-assembly process. Wipe the block and cap saddles clean of any oil and debris. Without lubrication, press the bearings into place and pay careful attention to bearing tang alignment. Depending upon the type of main bearings being used, there may be specific upper and lower halves. If there is a specific orientation, be sure the main bearings are correctly installed in the proper position. Refer to bearing instructions, or consult with the bearing manufacturer or your machinist if there is any question. Remember, saddle and cap numbers-1, -2, and -3 use the same bearings. The thrust bearing is installed onto number-4. And the widest bearing is installed onto the rear main saddle and cap. The main saddle bearings surfaces and rear main seal are liberally coated with assembly lube.
Step 5: Install Crankshaft
Be sure that the machinist installed a new 3/16 x 13 ⁄8-inch crankshaft keyway into the crank snout. If not, Dura-Bond produces one (number AK-001-P), which is available from your local parts store. The crank keyway is installed in a manner identical to the camshaft keyway. Gently set the crankshaft onto the lubricated bearings in the main saddle. Apply a liberal coating of assembly lube directly to the exposed journal surfaces.
Step 6: Install Main Caps
The main caps are set on their respective journals and gently pressed onto the alignment dowels by hand. The first four caps are numbered. The cap is correctly oriented if the crankshaft snout is to the left of cap number-1. If any cap requires slightly more persuasion, gently tap it with a soft hammer until the cap is firmly positioned on the dowels. Smear a dab of RTV sealer onto the mating surfaces of the main cap and block that surround the rear main seal when installing the rear main cap. The sealer fills in the micropores that might otherwise allow some oil seepage.
Step 7: Install Main Cap Bolts (Torque Fasteners)
The main cap bolt threads and just beneath the head are lubricated with 30W oil. The bolts of the first four caps are tightened with a 3/4-inch socket. Use a 15/16-inch socket to tighten the rear main cap bolts. Start at the number-1 cap and work toward the rear; tighten the bolts to 60 ft-lbs with a 1/2-inch-drive torque wrench. Each bolt is then tightened to 80 ft-lbs, and again to a total of 100 ft-lbs. The rear main cap bolts require one additional step and are tightened to 120 ft-lbs. Rotate the crankshaft several times by hand to be sure that there isn’t any binding or contact with the block, and that the assembly lube is evenly dispersed across the bearing and journal surfaces. If the crank rotates smoothly, the main cap bolt settings are rechecked with the torque wrench to be sure that the main caps are installed properly. The block is then rotated so the left hand bank of cylinders is parallel with the ground so the pistons can be installed.
Step 8: Arrange Piston Rings (Important!)
Liberally lubricate the cylinder walls with 30W oil, and rotate the crankshaft so the number-1 rod journal is at the bottom of its travel in relation to the block. Taking the piston-and-connecting-rod assembly designated for the number-1 cylinder, lubricate its wrist pin with oil and insert it into the number-1 cylinder with one hand while supporting the connecting rod from beneath with the other hand. Piston installation stops just before the piston rings contact the block. The piston rings are rotated so the end gaps of each are about 90 degrees apart from the next, to promote maximum cylinder seal. Exact gap orientation isn’t overly critical since the rings move about during normal operation. The entire ring pack is well lubricated with 30W oil.
Step 9: Compress Rings and Install Piston (Special Tool)
Compress the piston rings with a piston ring compressor and drive the piston into the cylinder with a non-marring tool, such as the handle of a soft-face hammer. Once the ring pack is well within the cylinder, set aside the piston ring compressor, and drive the piston completely into the block with one hand while supporting the connecting rod from underneath the block with the other hand. Continue gently driving the piston into the cylinder until the connecting rod bearing is firmly seated onto the crankshaft rod journal.
Step 10: Install Connecting Rod Cap and Nuts
Remove the connecting rod bolt cover and install the connecting rod cap. The bearing should still be coated with assembly lube and the cap must be orientated correctly to prevent backward installation. Use the appropriate lubricant recommended to lubricate the rod bolt threads. Pontiac specified 30-weight oil for the original fasteners in its cast connecting rod. Aftermarket manufacturers may suggest something different, such as the moly-based lube that RPM International suggests for the ARP bolts it uses. If there’s any question about the fasteners used during your rebuild, be sure to contact your machinist.. Use a 9/16-inch socket to firmly tighten the nuts before moving onto the next cylinder for piston installation. It becomes harder to rotate the crankshaft as more connecting rods are attached to it. I thread a spare harmonic balancer bolt into the crankshaft snout and rotate the engine with a 15/16-inch wrench.
Step 11: Tighten Connecting Rod Nuts(Torque Fasteners)
The same process outlined in the past three steps is used to install all the pistons on one cylinder bank. The block is then rotated so the remaining pistons can be installed in their corresponding cylinders. Once the eight piston-and-connecting-rod assemblies are installed, rotate the block until it is upside down. Then use the appropriate size socket for the rod nuts and a 3/8- inch-drive torque wrench to tighten nuts to OEM or aftermarket recommended specification, working from the front to rear. Refer to the OEM torque specification chart on page 139, or the aftermarket manufacturer’s specification sheet for the proper amount. Check with your machinist or connecting rod supplier for the appropriate torque specifications if any other connecting rod or fastener will be used during your rebuild.
Step 12: Install Lower Oil Dipstick Tube
Insert the lower oil dipstick tube into the intermediate tube in the block; the windage tray retains it from underneath. Add a drop of blue thread lock to the threads of the four bolts securing the windage tray to the main caps. Install the bolts with a 1/2-inch socket and tighten them to 15 ft-lbs. Pontiac stopped installing windage trays on its engines during the 1970s. In these instances, the lower dipstick tube is retained by a welded tab, which is bolted to the number-3 main cap. Install the bolts with the same tools and torque specifications. This is an excellent time to test fit the actual oil dipstick you plan to use to be sure it installs without binding. You m ay need to rotate the engine slightly before you simply insert the dip stick into the intermediate tube. If your Pontiac is equipped with air conditioning, be sure the upper dipstick tube is also installed during the test fit.
Step 13: Thoroughly Clean Oil Pump (Professional Mechanic Tip, Torque Fasteners)
Pontiac used oil pumps that generate a maximum oil pressure of 40- or 60-psi in most of its production engines. The Melling M54DS oil pump may be the most popular choice for modern rebuilds, and that’s what I am installing here. It’s wise to remove the bolts that secure the bottom plate to the oil pump body with a 1/2-inch socket. Remove the nut securing the pressure regulator spring and check ball with a 13/16-inch socket. Closely inspect the unit to be sure that it is completely free from any metal burrs or debris. Pay close attention to the orientation of the dimples machined into the gears, so that they can be reinstalled correctly. Remove small burrs with a small file or stone. Contact your machinist if you notice any significantly irregularities such as pits or machining errors. Otherwise, the bolts receive a drop of blue thread lock, and they and the pressure regulator nut are reinstalled and tightened to 15 ft-lbs.
Step 14: Install Oil Pump Pickup (Important!)
Installing the oil pump pickup can be a bit challenging for first-timers. A slip-fit design secures it to the body. I generally place the pickup in my home freezer several hours before installation, which causes the metal to contract slightly, making the installation a bit easier. Drive the pickup into place by sliding a 3/4-inch open-end wrench against the embossed collar on the pickup tube, and tap it in with a hammer. If you’re using an original oil pan, align the pickup at the midway point between of the slot that’s created by the recess cast into the oil pump body and the bottom plate when it’s fully seated. Consult the oil pan manufacture r if you’re using an aftermarket oil pan. Though rare, the oil pump pickup can fall out of the body, requiring major engine disassembly to repair. To prevent the pickup from falling out during normal operation, you can tack weld the body and pickup together. Your machinist can perform any portion of this step for you.
Step 15: Install Oil Pump (Torque Fasteners)
Drop the intermediate shaft that drives the oil pump into the block. Its pinch-tabs rest against the block’s cast loop, and the opposite end engages the oil pump drive on the pump body. Align the oil pump gasket and oil pump with the holes in the block, place a drop of blue thread lock on the bolts, and tighten them to 30 ft-lbs with a 3/8-inch-drive torque wrench and a 9/16- inch socket.
Step 16: Install Camshaft Thrust Plate
Rotate the engine 180 degrees, so it sits right side up to install the camshaft thrust plate. The plate limits the camshaft’s forward travel, and it contains a machined groove on one side, which supplies the timing chain with pressurized oil. Install the plate with the machined groove facing the camshaft. Place a drop of blue thread lock on the bolts. Use a 1/2-inch socket and a 3/8-inchdrive torque wrench to tighten the bolts to 20 ft-lbs. A new thrust plate should be used if the camshaft contact surface of the original appears scored in any way.
Step 17: Install Timing Set (Precision Measurement)
Install the timing set onto the camshaft and crankshaft snouts. Rotate the crankshaft so the number-1 piston is at TDC. Temporarily install the crankshaft gear onto the crankshaft snout to verify that its TDC timing dot is at the twelve-o’clock position. Even with lubrication, the gear should fit tightly on the crankshaft keyway without any wobbling or free play. Temporarily install the camshaft gear onto the camshaft snout. It, too, should fit tightly on its keyway. Rotate the camshaft so its timing dot is at the 12- o’clock position and remove the gears. Some prying may be required. Install the timing set as a unit while maintaining proper timing dot alignment. I use a Sealed Power roller set (number-3112) and liberally coat the timing chain with 30W oil prior to installation.
Step 18: Verify Timing Dot Alignment (Critical Inspection, Professional Mechanic Tip)
Always position the TDC timing dot on the crankshaft gear at the 12-o’clock position during timing set installation. However, the camshaft gear timing dot can be installed at 6 or 12 o’clock. Either position has no effect on camshaft timing and positions the camshaft in same relation to the crankshaft. It does, however, affect ignition timing. When the timing dots are aligned at 12 o’clock, the engine is at the number-1 firing position. With the cam gear at 6 o’clock, the engine is placed at the number-6 firing position. Since the crank rotates twice as fast as the camshaft, either position can be used as long as the distributor is installed accordingly. I routinely rotate the crankshaft several times, stopping the cam gear at the 6-o’clock position just to verify that the timing dots are exactly aligned with that position too. The crankshaft is then rotated one more revolution so the cam gear returns to 12 o’clock for the remainder of engine assembly.
Step 19: Install Fuel Pump Eccentric (Torque Fasteners)
The fuel pump eccentric is a two-piece design that consists of a fixed center and a floating outer bushing. A stamped tab fits into a corresponding hole on the cam gear. Install the cam gear bolt, using a drop of blue thread sealer on the threads. Use a 3/4-inch socket, and tighten it to 40 ft-lbs with a 1/2-inch-drive torque wrench. A helper may be required to keep the crankshaft from rotating. When finished with this step, I rotate the engine 180 degrees to perform the next steps.
Step 20: Install Timing Cover (Torque Fasteners)
The machinist should have thoroughly cleaned the timing cover along with the other parts. Upon its return, closely inspect it for any pits or cracks that could affect its ability to properly seal to the engine. Use a 5/16-18 tap to restore the fuel pump bolt threads. Gently drive the new front seal into place with a hammer. Many hobbyists use an excessive amount of RTV sealer around the coolant holes in an attempt to prevent leaks when installing the timing cover. Unless it or the block is pitted, I smear only enough to hold the new Fel-Pro gasket to the timing cover. Install the new Fel-Pro timing cover alignment sleeves into the bottom bolt holes of the timing cover, and fasten the unit to the engine with bolts and studs with nuts. If your studs were damaged during disassembly and your machinist didn’t supply you with new ones, you can source new 4-inch-long studs with 3/8-16 threads from a local hardware store or industrial fastener supplier. You can also use a stud that has 3/8-16 threads on one end and 3/8-24s on the other. You may need to refer to your disassembly photos to reference the year-specific locations and the number required. Thread the coarse-thread end of the stud (3/8-16) into the block until it bottoms out. Use a 9/16- inch socket to tighten the timing cover’s nuts and bolts to 15 ft-lbs with a 3/8-inch-drive torque wrench.
Step 21: Install Oil Pan Gasket
Apply a very light coating of RTV sealer onto the oil pan rail of the block and timing cover. Lay a new Fel-Pro oil pan gasket into place. The sealer is used only to keep the gaskets from moving around during oil pan installation. However, the joints where the gaskets meet receive a bead of RTV sealer to prevent leaks. Pontiac used at least three rear pan gasket designs over the years. The type required for your rebuild depends upon the engine and oil pan vintage. Fortunately, the Fel-Pro gasket kit contains the various types. In this instance, the five tabs are cut off the rubber seal, so it can be laid on the main cap and a bead of RTV sealer applied to each end to prevent leaks.
Step 22: Install Oil Pan (Torque Fasteners)
The oil pan is another component that the machinist should have thoroughly cleaned for you. Simply lay it onto the gaskets and use a total of 18 bolts to fasten it to the block and timing cover. A 7/16-inch socket and 3/8-inch-drive torque wrench is used to tighten most of the bolts to 12 ft-lbs. Some engines use two slightly longer bolts at each rear corner of the oil pan, which are accompanied by steel reinforcing straps. If present, these bolts are tightened to 20 ft-lbs when used with the straps. Reproductions are available if yours are missing. Tighten the oil pan drain plug to 22 ft-lbs with an 11/16-inch socket.
Long Block Assembly
Step 1: Install Cylinder Head Gaskets
Rotate the engine 180 degrees and prepare the deck surfaces for cylinder head gasket installation. Check to be sure the machinist reinstalled the four cylinder head alignment dowel pins in the deck surface. If not, a Dura-Bond replacement set (number AD-927-P) can be sourced from a local auto parts store. They are easily tapped into place with a hammer. Using a lint-free cloth and residue-free solvent, wipe the machined surface clean of any contaminant that could impede the gasket’s ability to properly seal the cylinders. The Fel-Pro head gasket requires no additional sealer and is installed dry. Pay close attention to its proper orientation; the correct side of the gasket faces up. Lay the gasket onto the block and press it onto the cylinder head alignment dowels.
Step 2: Install Cylinder Heads
The cylinder heads should still be fully assembled from the pre-assembly process. The freeze plugs and coolant nipple installed during preassembly require that the cylinder heads be installed on a specific side. Orient the cylinder heads so the coolant nipple is on the passengerside rear and a freeze plug is on the driver-side rear. A cylinder head is installed by lifting it over the block deck surface and carefully aligning it with the alignment dowels until it drops into place. Use caution to prevent pinching your fingers! Then thread a long head bolt (by hand) into the center hole to prevent the head from falling off until other cylinder head bolts can be installed.
Step 3: Install Cylinder Head Bolts (Torque Fasteners)
Pontiac used cylinder head bolts of various lengths on any given engine. Refer to your pictures and/or disassembly notes to determine the proper locations. If there’s any question about their orientation, set a cylinder head on its side and rearrange the bolts until an equal number of threads protrude from the deck surface. Tighten the head bolts with the specific sequence that’s intended to evenly load the cylinder head and crush the gasket. It starts at the center and spirals outward. If you’re using original Pontiac bolts, lubricate the threads and beneath the head with 30W oil. Tighten the bolts to 60 ft-lbs with a 3/4-inch socket and a 1/2-inch-drive torque wrench. Tighten the bolts to 80 ft-lbs in that same pattern, and use a final torque setting of 95 ft-lbs. If you’re using aftermarket fasteners, reference the manufacturer’s recommended torque specification and thread lubricant. No thread sealer is required unless you’re rebuilding a 301 (or 265 variant).
Step 4: Check Pushrod Length (Precision Measurement)
Original Pontiac pushrods measure 5/16-inch wide and 9.13 inches long. As long as they are not bent, originals can be reused in rebuilds that use stock-replacement flat-tappet camshafts, but only if the block or cylinder heads haven’t been milled excessively. Aggressive flat-tappet and roller camshafts almost always require special-length pushrods to maintain optimal valvetrain geometry. The components required to determine proper pushrod length are a pair of lifters and rocker studs, one rocker arm that will be used on the engine, and an adjustable pushrod. The pushrod is adjusted to a length that puts the rocker tip near the center of the valvestem while the lifter is positioned on the base lobe of the camshaft, so it doesn’t roll off the edge of the valvestem at peak lift. After the proper length has been determined, measure the adjustable pushrod with a caliper. The required length in this instance is 8.55 inches. A diameter of 11/32 inch is recommended, whenever possible, to combat deflection.
Step 5: Paint Engine (Professional Mechanic Tip)
Waiting for the custom pushrods to arrive from Comp Cams proved to be the perfect opportunity to paint the engine and, specifically, the portions that are otherwise inaccessible when the engine is completely assembled. Pontiac Blue Metallic Paint (number 62200) from OEM Paints closely resembles the original shade of light-metallic-blue paint that Pontiac used from 1966 to 1970. OEM Paints uses a specific formulation when designing its complete line of quality engine paints that resist high-temperature discoloration. OEM’s Pontiac engine colors are readily available in a spray can. The valley pan is set in place to prevent painting the lifter valley, and painter’s tape is used to mask off any area that shouldn’t be painted, particularly any of the machined flanges and the distributor hole.
Step 6: Install Rocker Arms and Guide Plates (Torque Fasteners)
Original Pontiac guide plates are sufficient if stock-diameter pushrods are reused, but thicker aftermarket pushrods may require new guide plates. Replacement guide plates from Sealed Power are installed along with 7/16-inch rocker studs from ARP. The guide plates are sandwiched between the cylinder head and rocker studs. Tighten the rocker studs to 55 ft-lbs with an 11/16-inch socket and 1/2-inch-drive torque wrench.
Step 7: Install Lifters, Pushrods and Rocker Arms
Thoroughly coat the camshaft lobes with the manufacturer’s suggested break-in lubricant. Soak the lifters and rocker arms in 30W engine oil for several minutes. If a flat-tappet camshaft is used, coat the lifter’s face with camshaft break-in lubricant. Install the lifters into the lifter bores. They should easily slide into place. Set the new pushrods into place in the lifter cups. Apply a drop of assembly lube to the roller rocker pushrod cup, and install the rocker arm onto the rocker stud, and thread the lock nut into place.
Step 8: Set Valve Lash (Professional Mechanic Tip)
Production engines generally use a non-adjustable valvetrain. If your rebuild includes a stock-type camshaft, stamped steel rocker arms, and original rocker studs with a shouldered design, lubricate the rocker’s pivot balls with assembly lube and lubricate the nuts with 30W oil. Tighten the nuts to 20 ft-lbs with a 5/8-inch socket and 3/8-inch-drive torque wrench. An adjustable valvetrain gives complete control over valve lash, and that can translate into extended high-RPM operation and a slight power increase. It is required when using an aggressive hydraulic, solid flat-tappet, or any roller cam. Set the lash on a solid camshaft with a feeler gauge placed between the rocker arm and valvestem. The amount of required lash can range from .010 to .030 inch depending upon the camshaft and application. Any solid cam should be accompanied by recommended valve lash specifications from the manufacturer. The hydraulic lifter limits the amount of valve lash on a hydraulic camshaft. A quality set of roller rocker arms includes a positive lock nut (often referred to as a “poly-lock”), which has an internal screw that locks against the rocker stud to positively set valve lash. Aftermarket stamped steel rocker arms usually include a “jamb nut,” which is serrated at the top and must be replaced after a few valve lash adjustments. The less a hydraulic lifter’s plunger travels, the more it acts like a solid lifter, possibly increasing performance and extending engine RPM. Because the internal tolerances and operational characteristics of hydraulic lifters differ among the manufacturers, consult with your lifter supplier for the recommended amount of preload; you are likely to end up between 1/4 and 1 turn past zero lash. To properly set lifter preload when using a hydraulic cam, rotate the pushrod with two fingers and slowly tighten the lock nut until drag on the pushrod can be felt. Watch the lifter plunger closely to be sure it hasn’t compressed. Using a 5/8-inch wrench, tighten the lock nut one-third turn more, which preloads the lifter a minimal amount, minimizing valve lash and internal plunger travel. Insert a hex-head wrench into the internal locking screw, and tighten it and the nut against the rocker stud as a unit. The total amount of preload is about half a turn in this instance.
Step 9: Install Valley Pan (Torque Fasteners)
The valley pan is another component that the machinist should thoroughly clean for you. It is a two-piece design that’s welded together and contains an internal baffle intended to prevent the engine from ingesting engine oil mist through the positive crankcase ventilation (PCV) valve that is located within it. After years of use, sludge generally develops from the continuous oil mist is it exposed to, which is difficult to remove. Absolutely no abrasives should ever be used to clean the valley pan! It’s full of cracks and crevices that can hide small particles that can eventually fall into the engine or be drawn in by the PCV system. If your machinist cannot get the internals completely clean after soaking in a hot tank and/or spray washing it, it may be wise to invest in a replacement. Glue the appropriate Fel-Pro gasket to the valley pan gasket rail with gasket adhesive. If the gasket rails are not bent, RTV sealer should not be required on the block. Once dry, the valley pan is tightened to 3.5 ft-lbs with a 7/16-inch socket. If you’re using a roller camshaft, the valley pan must be test fit to verify that sufficient lifter clearance exists. To do this, apply assembly lube onto the highest point of the lifter bodies, install the valley pan, and rotate the engine several times. Remove the valley pan and check for any signs of lifter contact. Minor clearance is gained by dimpling the contact areas of the valley pan with a small hammer. Major clearance issues once required significant pan modifications, but a new valley designed to accommodate roller lifters may be the best option. The new Tomahawk valley pan from Pacific Performance Racing is a top-quality unit that appears, installs, and functions just like an original but provides sufficient clearance. It is an excellent choice whenever a replacement valley pan is required.
Step 10: Install Water Pump (Torque Fasteners)
A new high-quality FlowKooler water pump was sourced for this rebuild. It is installed onto the timing cover, but not before the internal divider plate, which properly directs and regulates coolant, is installed. The gasket surfaces of the timing cover and water pump (and divider plate in some instances) receive a thin coating of RTV sealer to fill any pits or pores that could lead to coolant leaks. Depending upon the model year, the water pump is secured to the timing cover with 9 to 11 bolts and possibly some nuts with studs. Tighten them with a 1/2-inch wrench to 15 ft-lbs. In later years, two sleeves with rubber seals are used to seal the timing cover and internal divider plate. The FelPro gasket kit should contain the appropriate gaskets and new rubber seals.
Step 11: Install Harmonic Balancer (Torque Fasteners, Important!)
A harmonic balancer is a key engine component that must function exactly as intended, which is to dampen harmful frequencies that travel through the crankshaft. Any variance could cause catastrophic engine damage and any questionable original should be replaced. A number of new 1968-and-later replacements are available. Most Pontiac vendors can supply one. Otherwise, any Pontiac harmonic balancer can be rebuilt by companies that specialize in this service. (This 1967 unit was renewed a few years ago.) The balancer should slide onto the crankshaft snout, fit snuggly on the crankshaft keyway, and not wobble in any way. A gear press can be used to persuade stubborn units, but a balancer should never be forced on, nor should it be struck with a hammer. Install the balancer bolt with a 15/16-inch socket and tighten to 160 ft-lbs with a 1/2-inch-drive torque wrench. A long, hardened-steel 1/2-inch-20 stud can be threaded into a flywheel bolt hole on the flywheel register and locked against the engine stand to keep the engine from rotating so full torque can be applied to the balancer bolt. The balancer bolt must be tightened to the appropriate torque setting or significant engine damage could result. Once installed, rotate the engine so the balancer timing mark is aligned with the TDC mark on the timing cover. A helper can place a finger over the number-1 spark plug hole to verify that the engine is building compression as the piston travels toward the top. This ensures that the number-1 cylinder is on the compression stroke, which is required to properly install the distributor. The lower accessory pulley is also installed at this time; be sure to include the reinforcing ring, which serves to prevent the pulley bolts from tearing out under normal operation.
Bolt-On Components Installation
Step 1: Install Intake Manifold (Torque Fasteners)
Lay a new Fel-Pro intake manifold gasket onto the intake manifold flange of each cylinder head. Use a couple small dabs of RTV sealer to hold them in place. The rubber ring that seals the coolant crossover to the timing cover is also held in place with RTV sealer. In order to prevent leaks, I smear a small amount of sealer on the timing cover surface that contacts the intake manifold to seal any pits and pores. Set the manifold carefully into place. By hand, thread-in the 10 intake manifold bolts, paying close attention to gasket alignment during installation. You may need to refer to your notes to properly position certain bolts. With the bolts hand-tight, install the long bolt that seals the timing cover and intake manifold. It draws the manifold forward as it is tightened to 15 ft-lbs with a 7/16-inch socket and 3/8-inch-drive torque wrench. The manifold bolts are then tightened to 40 ft-lbs with a 9/16-inch socket and a 3/8-inch torque wrench. Do this in a crisscross pattern, working from the center outward.
Step 2: Install Thermostat Housing (Torque Fasteners)
A new 180-degree thermostat is set into the coolant crossover. The intake manifold surface receives a light coating of RTV sealer to seal any pits that could cause leaks. The machinist surfaced the thermostat housing with a stationary belt sander. Set a new gasket in place and tighten the bolts and/or nuts to 30 ft-lbs with a 9/16-inch socket and 3/8- inch-drive torque wrench.
Step 3: Install Valve Covers (Torque Fasteners)
Original oil drippers may not fit when using aftermarket roller rocker arms. They can generally be omitted without compromising component longevity, if you’re using roller rockers. Oil drippers were welded to the valve cover in later years, and some adjustment may be required with aftermarket rocker arms. If you’re using the bolt-on style, fasten the oil drippers to the head bolt studs with a 9/16-inch socket to install the nuts, and tighten them to 30 ft-lbs with a 3/8-inch-drive torque wrench. Glue a new 1/8-inch-thick FelPro gasket to each valve cover with gasket adhesive and set the valve covers onto the cylinder heads. Install the valve cover bolts with a 7/16-inch socket and tightened to 8 ft-lbs with a 3/8-inch-drive torque wrench. If additional clearance is needed, Fel-Pro also offers a 1/4-inch-thick gasket for this purpose.
Step 4: Install Spark Plugs (Precision Measurement, Torque Fasteners)
A highvoltage ignition system with an electronic distributor replaces the original contactpoints distributor. Set the gap on the AC Delco R45S spark plugs at .050 inch. Install the gasket-seat spark plugs with a 13/16-inch socket and tighten to 25 ft-lbs with a 3/8- inch-drive torque wrench. Later cylinder heads use tapered seat plugs, which are tightened to 15 ft-lbs with a 5/8-inch socket.
Step 5: Install Oil Filter Housing (Torque Fasteners)
Install the oil filter housing and use a new Fel-Pro or similar gasket. Tighten the three bolts to 30 ft-lbs with a 9/16-inch socket and a 3/8-inch-drive torque wrench.
Step 6: Install Fuel Pump (Torque Fasteners)
A new stock-replacement fuel pump from Carter replaces the worn-out original. Install a new Fel-Pro or similar gasket. The bolts securing the fuel pump to the timing cover are tightened to 25 ft-lbs with a 7/16-inch socket and 3/8-inch-drive torque wrench.
Step 7: Pre-lube Oil System (Special Tool, Important!)
Install a high-quality oil filter (AC Delco PF24, NAPA Gold 1258, or Mobil M1-203) onto the housing and tighten it by hand. Fill the crankcase with 6 quarts of oil. (I prefer Brad Penn 30W break-in oil.) A special additive for a flat-tappet camshaft may also be required. For that and the recommended break-in procedure, you must consult the camshaft manufacturer. Thread a mechanical oil pressure gauge into the oil-pressure sending unit hole in the oil filter housing. Using a reversible air drill or a high-power electric drill and an oil system priming tool, spin the oil pump counterclockwise for several seconds, so oil is drawn into the pickup and the entire oiling system is pressurized. The gauge should show steady and consistent pressure while the pump is spinning. Repeat the process several more times to be sure that the oil distributes throughout the entire engine. Some hobbyists claim oil must be present at every pushrod or rocker arm. I’ve found that it’s not always possible, depending on lifter position. If steady oil pressure occurs and you can see oil flowing by (looking in the valve covers), then there is rarely any issue if the oil system plugs were properly installed. If you don’t see oil flowing to the top end after several minutes of priming, rotate the crankshaft 90 degrees and repeat the process. You can rotate the crankshaft as many times as necessary, just be sure to return the number-one cylinder to TDC on the compression stroke.
Step 8: Install Distributor
A points-type distributor can provide sufficient performance, and breakerless conversion kits to convert it from mechanical to electronic operation are available from many companies. Here, I sourced a new HEI from Pertronix instead of salvaging a worn original. Its fit and function is identical to an original Pontiac HEI. If you’re using a roller camshaft, replace the distributor gear supplied by Pertronix, with a polymer gear from BOP Engineering, which is compatible with the steel roller camshaft. With the number-1 piston at TDC on the compression stroke, a spark plug wire terminal is designated as number-1. Align the rotor tip so it points at the corresponding terminal when dropping the distributor in place. You may need to rotate the oil pump shaft with a large screwdriver so it aligns with the distributor drive. After the distributor is fully seated in the block and the rotor tip is pointing at the designated number-1 terminal, rotate the distributor clockwise slightly, which advances timing for initial startup. Install the distributor hold-down clamp with a 9/16- inch socket. Firmly tighten it, but it doesn’t receive final torque until after the break-in procedure, so timing adjustments can be made after initial startup. Using a counterclockwise pattern, install the distributor cap and route new spark plug wires to the cylinders. The firing order is 1-8-4-3-6-5-7-2. I prefer stock-replacement AC Delco plug wires in applications where original appearance is a concern and Taylor plug wires elsewhere. AC Delco plug wires can be sourced from a local parts store. Taylor wires are readily available from any large mail-order supplier.
Step 9: Install Flywheel/Flexplate (Torque Fasteners)
If your Pontiac uses a manual transmission, a new flywheel may be required for the rebuild. I prefer the steel units produced by Centerforce. New stock-replacement flexplates (for automatic transmission) are readily available from many OE suppliers. Any new flywheel or flexplate should be balanced with the reciprocating assembly. Attach an engine lift plate to the carburetor flange with 5/16-18 x 1-inch bolts. Tighten the bolts very tightly with a 1/2-inch socket. It’s lifted slightly with an engine hoist and removed from the engine stand. With a helper holding the engine steady, install the flywheel or flexplate onto the crankshaft flywheel flange. The flange features a unique bolt pattern, so the flywheel may need to be rotated to properly align the bolt holes. Place a drop of blue thread lock on the bolts and install. Have a helper prevent the crankshaft from turning by using a 15/16-inch socket on the harmonic balancer bolt and supporting it with a long breaker bar. Tighten the bolts to 95 ft-lbs with a 5/8-inch socket and 1/2-inch-drive torque wrench. It’s unlikely that your machinist removed the bell-housing locating dowels, but be sure the two 5/8 x 1-1/8 inch dowels protrude from the back of the block. If they are missing, Dura-Bond replacements (number AD-009-P) are readily available from a local parts store. The engine is now ready for transportation or installation into the vehicle.
Step 10: Prepare for Transportation
If the engine is transported, an engine cradle like this from Butler Performance should be installed. It bolts to the motor-mount and bell-housing flanges and safely supports the engine from below. Its low-slung design helps prevent the engine from tipping over while being transported. The original motor mount bolts to the engine stand with a pair of 3/8-16 x 1-1/2-inch bolts. The bolts are installed very tightly using 11/16-inch and 9/16-inch sockets, respectively.
Step 11: Engine Assembly Complete
It’s almost ready to run! The 400 is nearly complete and is ready for initial startup and break-in on an engine dyno, test stand, or in the vehicle. Only a few remaining components need to be installed, and those parts are bolted on either just before or after installation into the vehicle. Those include the engine mount brackets, exhaust manifolds, carburetor and fuel lines, various wiring and vacuum harnesses, and all accessories and associated brackets.
Written by Rocky Rotella and Posted with Permission of CarTechBooks