Performance Engine Assembly Tips, Part 1 Everyone has to start somewhere, so here are some initial focus areas. Build, text and photos by Mike Mavrigian
Mike Mavrigian owns and operates Birchwood Automotive in Creston, Ohio, where he builds custom engines and street rods and performs vehicle restorations. He has written thousands of technical articles as well as nine books on automotive technology during the past 30 years. Mike can be reached at (330) 435-6347 or birchwdag@frontier.com. Visit Birchwood’s website at birchwoodautomotive.com.
Editor’s note: This is the first article in a two-part series offering performance engine assembly tips.
Not everyone has the budget (or desire) to enlist a pro engine shop to perform a build from start to finish. They may turn to your shop for parts and advice, but plan to do the bulk of the work themselves.
In some cases, the enthusiast may start the process by purchasing a used engine, perform their own disassembly and then turn over the block, heads, crank and rods to a machine shop, with plans to do their own final assembly. In other cases, they might purchase a short block (where the block has been machined, the crank and rods reconditioned or replaced, and the camshaft installed), or a long block, which has all of that plus the heads installed as well.
Novice engine builders often have questions regarding engine assembly and may be confused by various procedures found on the internet. Here, we’ll attempt to offer real-world advice that should make any engine assembly go smoothly.
START WITH CLEAN BLOCK HOLES
Whether you’re dealing with a used/reconditioned block or a new block, one of the first things to do is to check all female threaded holes for cleanliness—specifically the block’s cylinder head bolt holes. Never assume that all female hole threads are “good to go.”
Wearing safety glasses, blow compressed air into each hole and inspect for any debris. There must be no contaminants (and in blind holes, make sure there is no fluid, which would result in hydro-locking that prevents sufficient clamping).
Once you confirm that no debris is present, test-fit a fresh bolt for proper thread engagement. If the bolt presents noticeable resistance, the threads may be slightly deformed or rusted. In this case, use a dedicated thread chaser to clean the threads, then blow any debris out with compressed air.
Do not use a cutting tap, which can remove metal and weaken the threads. Cutting taps are designed to create new threads, not to recondition existing threads. A dedicated thread chaser tap will not remove any metal. Chaser taps are readily available from a variety of sources in all popular thread sizes.
Cleanliness is the first order of business before any aspect of assembly. Keep all parts clean and organized.
HIGH CLAMPING-LOAD FASTENER LUBE
Fastener installation is important for all engine fasteners (bolts, nuts, studs), but the most critical include cylinder head, main cap and connecting rod fasteners. Depending on application and builder preference, commonly used thread lubricants may include engine oil, moly anti-galling paste, EPL lubes such as CMD No. 3 and specialty fastener lubes such as ARP’s Ultra-Torque lube.
With, for lack of a better term, “traditional” lubes, it may be advised to cycle new fasteners a number of times before the fastener’s torque application “settles.” A high clamping-load application threaded fastener may not achieve desired clamping load on the first torque application.
It may be necessary to torque, relax, retorque, relax, etc., a number of times until the fastener settles and achieves the desired clamping load. This is common with the use of many lubricants including oil, moly or an EPL (extreme pressure lubricant).
To avoid the need to cycle/condition the fasteners, ARP developed its Ultra-Torque fastener assembly lube, which years ago replaced its moly lube. The current lube was developed to allow the fastener to achieve full clamping load capability in the first torque step and maintains the same clamping load in future torque applications (according to ARP, within less than 5% deviation). This greatly reduces the “scatter” effect among a group of fasteners, such as with a set of head bolts, with increased accuracy and consistency.
Note: While many of us continue to refer to any ARP assembly lube as “ARP moly” (merely out of habit), the Ultra-Torque lube contains no moly and is a uniquely developed lubricant specifically designed for high-performance fastener lubrication.
Many assembly lubricants and sealants are available for general assembly, dedicated high-pressure applications and threaded fasteners.
A dedicated low-friction threaded fastener lube is essential to obtaining accurate and consistent torque values and clamping loads.
CONNECTING ROD TORQUE
Several high-performance connecting rod manufacturers may list two torque values for their supplied rod bolts, based on the use of oil or moly (again, we use the term “moly” in a rather generic sense). One of the primary reasons published torque values differ has to do with the coefficient of friction between lubricants (oil or a dedicated low-friction thread lube).
If the bolts (regardless of brand) are supplied with the new connecting rods, always follow the rod maker’s published torque values. A slightly higher torque value may be listed with the use of oil and a slightly lower value may be listed with the use of a low-friction lubricant because of the differences in friction.
The more “slippery” the lube, the less applied torque may be needed. If rod bolts are treated with oil, but the torque value for a low-friction lube is followed, the fastener may be undertorqued with reduced clamping load. By the same token, if the oil spec is followed but a low-friction lube is applied, the applied torque may overstress the fastener.
Simply put, pay attention to the published specs based on the type of lube.
In addition to published torque specs, it is highly recommended to also monitor rod bolt stretch. The rod maker will provide a maximum-allowable amount of bolt stretch. Both torque and bolt stretch can differ slightly based on the rod bolt material, bolt diameter and bolt length.
The bolts must achieve a slight amount of installed stretch in order to provide the necessary clamping load. But if stretched too far, beyond the bolt’s elastic range, bolt failure is a very real possibility. Invest in a rod bolt stretch gauge or borrow one from a friend.
Using a stretch gauge is not overly complicated. First, place the bolt onto the gauge and zero the dial. Once that bolt has been torqued to spec, place the gauge back onto that bolt and note how much longer the bolt has become. Do this for each rod bolt.
After chasing threads, clean with a solvent and blow with compressed air. Quality chaser taps feature a flat end instead of a taper, enabling you to clean the bottom of blind holes.
For each and every rod bolt, first place it onto the gauge and once again zero the gauge dial. You cannot just zero the gauge on one bolt and then use that reference for the remaining bolts. Even though quality aftermarket rod bolts are well made, there will be slight differences in shank length—that’s simply the nature of bolt manufacturing.
Yes, checking bolt stretch will add time to the build, but it’s well worth it to verify that the rod bolts have achieved sufficient stretch and have not stretched beyond the allowable maximum. Generally speaking (again, this will vary based on the specific bolts), proper stretch will likely be in the range of 0.0025 to 0.0045 inch.
Finally, it’s a good idea to make a record of each bolt’s torque and stretch, just in case you ever have a problem. This data can help pinpoint an issue down the road regarding rod bearing or bolt failure. Record each bolt’s location, torque and stretch.
FINAL ASSEMBLY LUBES
Consider the assembly lubes for rings and cylinder walls, camshafts, bearings, oil pumps and valvetrain parts.
Major factors to consider for an assembly lube include:
• Oil solubility. The lube must be able to mix with the sump’s oil supply. Any grease-based lube must be oil-soluble. If not, once circulated to the sump and pumped back into the circuit, it can pose risks of plugging orifices and small passages.
• “Stickability.” The assembly lube should provide enough cling/good adhesion properties to stay in place after application without dripping off.
• Anti-wear properties. Especially at high-load areas such as bearings, rockers, cam lobes, lifters, valve stem tips and pushrods, the lube must be able to protect frictional surfaces from scuffing and micro-welding. Initial start-up poses the biggest risk in terms of wear, scuffing or seizing, making assembly lubrication absolutely critical.
Today’s market offers a dizzying array of sources for engine assembly lubes. Without trying to promote one over another, quality assembly lubes are offered by trusted brands such as Clevite, Brad Penn, COMP Cams, Permatex, Isky, AMSOIL, Red Line Oil, Royal Purple, Torco, CRC, Lucas and others.
BEARINGS
Main bearings, rod bearings and cam bearings may be initially coated with any acceptable lube such as engine oil or engine assembly lube, but using an assembly lube that offers a good “cling” factor is recommended to prevent drain-off while the engine sits prior to initial firing. This is especially important if the engine will be stored for an extended period prior to initial firing, even though you plan to pre-oil prior to start-up.
There are several good synthetic engine assembly lubes that offer very low coefficients of friction and that remain on the surfaces even after extended periods of storage. Naturally, we need to remember to also lube thrust bearing surfaces as well.
Note: During crankshaft installation, once the main caps have all been seated—with cap bolts engaged but before torquing—use a mallet to tap the crankshaft back and forth. This will help align the main caps, avoiding bearing damage. After tightening to about 10-15 pound-feet, tap again fore and aft. As always, tighten the fasteners in stages (10-, 25-, 35-, 45-pound-feet, etc., to final torque).
Clean all threaded holes in the block with a purpose-designed chaser tap. A common cutting tap will remove metal, as opposed to a chaser tap that is designed to clean threads, removing any burrs or slight deformities.
For high clamping-load applications such as cylinder heads, main caps and rod bolts, apply a dedicated low-friction thread lube to the underside of the bolt head (and both sides of a washer and the underside of a nut if dealing with studs) in addition to coating the threads. This allows you to lube all friction surfaces that would otherwise compromise the torque value.
Regardless of the application, it’s a good idea to always apply a thread lube to any stainless steel fastener to prevent potential galling.
Bearings should be coated with a high-pressure lube that clings and sticks to the surface to ensure lubrication upon initial start-up. Make sure the lube is oil-soluble.
Place the rod bolt onto the stretch gauge and adjust the dial to zero.
CAMSHAFT
Prior to camshaft installation, the cam lobes must be coated with an appropriate lubricant. Flat tappet cams absolutely require a high-pressure lubricant that will prevent premature wear between lobes and lifters. It’s always best to follow the cam maker’s. recommendation in terms of lube choice (cam makers often include the recommended lube with a new cam).
Granted, while roller cams are not as critical in terms of break-in, some cam makers will specify a particular break-in lube, while some builders prefer to simply use any quality engine assembly lube to coat the lobes. Even though we don’t encounter the same frictional forces between the lobes and the lifter roller bearings, a high-pressure lube is recommended.
Since many commonly available engine oils today have greatly reduced levels of critical high-pressure ZDDP (zinc dithiophosphate, commonly referred to simply as “zinc”), a flat tappet camshaft requires the use of a specific engine oil that features adequate levels of zinc phosphate. Oil makers such as Brad Penn, Joe Gibbs, Royal Purple, Red Line Oil, COMP Cams and a myriad of other brands offer these specialty oils, both available for initial break-in and for long-term use.
An option is to run your oil of choice and add a bottle of zinc concentrate, which is offered by a number of manufacturers. An adequate level of extreme-pressure formulation (ZDDP) is needed for both break-in and for routine engine operation.
Be aware that some dedicated “break-in” oils do not contain corrosion inhibitors. As a result, only use a dedicated break-in oil for engine break-in, changing the oil and filter after 100 to 500 miles of driving, then switch to the oil of choice.
LIFTERS
Flat tappet lifter faces require the same high-pressure break-in lubricant as needed for the cam lobes. The lifter body may be coated with engine oil or a preferred assembly lube.
Without disturbing the gauge dial, place the gauge on the torqued bolt to read stretch.
Do not confuse engine assembly lube with fastener assembly lube. A dedicated engine fastener lube is not designed to lubricate moving parts. Roller lifters may be lubed with engine oil or an engine assembly lube of your choice.
Pay attention to the lifter maker’s recommendations for the engine’s sump supply, as some high-performance, close-tolerance roller lifters require a relatively low-viscosity engine oil (5W-30 for example). When dealing with hydraulic lifters, it’s common practice for some builders to soak them in oil and sometimes to try to pump them up prior to installation.
Use care here, however, as some performance hydraulic roller lifters have been pre-charged with oil during manufacturing. Check with the maker before attempting to perform a pump-up.
TIMING CHAIN/GEARS
Common practice involves soaking a timing chain in clean engine oil, preferably overnight. If a gear drive is involved, a high-pressure assembly lube should be applied to all gear teeth.
For a chain or gears, your choice of lube may differ. Some may prefer 30W engine oil and others synthetic engine oil. For a gear drive setup (as opposed to chain drive), you may prefer a high-pressure lube such as CMD No. 3 or a synthetic assembly gel.
CYLINDER WALLS
Prior to piston installation, each cylinder must be thoroughly cleaned using a mild solvent such as isopropyl alcohol and clean, lint-free towels.
Continue to wipe the cylinder walls, frequently switching to fresh towels, until the final towel is clean and shows no evidence of residue. A thin application of lubricant can then be applied.
Most builders agree that cylinder walls and rings should be treated only with petroleum engine oil. Using a full-synthetic oil poses a potential concern with regard to a possible delay in piston ring seating.
While a synthetic assembly lube, such as Royal Purple’s Max Tuff (to cite but one example), may be an outstanding choice for coating bearings, pushrods, rocker arms, piston wrist pins, etc., avoid using a full-synthetic lube on piston rings and/or cylinder walls, as this type of super-slippery lube may hinder initial ring seating.
Granted, there is debate regarding the use of a full-synthetic oil during assembly (on rings and walls) and for an engine’s initial break-in run. While a super-slippery full-synthetic oil is commonly avoided for break-in, a variable involves how the cylinder walls were finished.
When dealing with walls that were finely honed and plateau-brushed, this should allow rings to seat much quicker, wherein a full-synthetic might not pose an issue.
For reassurance, most builders will probably agree that initial break-in should be performed with a “conventional” petroleum oil.
Once rings have seated, the decision to run a full-synthetic oil is then up to the builder or owner. But again, to address the concerns during engine assembly, it’s wise to avoid using a full-synthetic lube on cylinder walls and rings.
Do not install studs using a high degree of torque. Cylinder head studs should be installed hand-tight (although some stud makers may specify a very light torque value). The required clamping load will result from tightening the nut.
Cylinder walls and rings may be coated with engine oil or an approved assembly lube. However, avoid the use of a full synthetic lube or oil in order to better allow ring seating during start-up.
