Jim Smart
October 5, 2006
Marvin "Dr. McAfee" of MCE Engines with a new patient.

One of the most exhausting aspects of 25 years in automotive journalism has been watching some of the things people do during engine builds that lead to failure. There are lots of engine-building myths and urban legends that are just plain, old-fashioned wrong. And, people get just plain, old-fashioned careless, forgetting things that are crucial to a solid, dependable engine build.

Despite all the shoptalk we've heard through the years, there are many misconceptions about engine building. Enthusiasts make them, and so do magazines. We've made a few of them ourselves through the years-incorrect torque values, carb-selection misinformation, incorrect cam selection, seals installed backwards, flopped head gaskets (it's getting awful hot in here), port jobs that led to water jacket penetration, bad balance jobs, snapped poly locks from overtorquing, dropped valves (ouch!), valve-to-piston contact (ouch!), slightly out-of-the-hole piston deck height, and more.

Engine failure happens when we don't do the job properly, but sometimes it happens through no fault of our own-we become victims of material failure. This is why we hold our breath anytime we fire an engine for the first time.

Our goal here is to help minimize the risk of engine failure with time-proven tips from some of the most seasoned engine builders in Southern California, including Marvin McAfee and Benton Jackson of MCE Engines, John DaLuz of JMC Motorsports, Mark Jeffrey of Trans Am Racing, and Jim Grubbs of JGM (Jim Grubbs Motorsports).

Carburetor Sizing

We get this one wrong more times than we get it right because we tend to believe bigger is better, and that it means more power. But that's not always the case; sometimes it means less power. Carburetion that's too small will stifle an engine and won't allow high revs, where real horsepower is made. But a smaller carburetor can actually improve torque off-idle and at midrange where it's needed on the street. Low-end torque is what gets you away from a traffic light faster than the other guy. Horsepower is what keeps you roaring along at high rpm once you get going, and it's what happens at wide-open throttle when you're moving at speed. For exceptional street performance, you want a nice balance of low- to midrange torque and high-rpm horsepower, dictated by vehicle weight.

Overbuilding

Too many people build way more engine than necessary. This means you're spending more money and time than you need to. Rule of thumb-build for the kind of driving your engine will be exposed to most. If the car is your daily driver, be modest in your approach, with a good roller cam that will give you excellent low- to midrange torque, with less emphasis on horsepower. There's nothing wrong with a flat-tappet camshaft if you can't afford a roller. Fit your engine with a dual-plane intake manifold and conservatively sized carburetor. If you're going to do some Saturday night drag racing or weekend road racing, step up the power a bit with more cam duration, modification of lobe centers, more lift, and a pinch more carburetor. In most cases, use of single-plane manifolds for street use is not a good choice because they're designed for high-rpm horsepower, not good low-end street torque. Be honest with yourself during engine planning. How much engine do you really need?

MCE Engines Quick Tip:
Want a hot street machine? A good starting point is a power-to-weight ratio of 10:1-1 hp for every 10 pounds of vehicle weight.

Cylinder Head Selection

Again, bigger isn't always better, especially for street use. Large-port heads, like Edelbrock Victor Jrs. or Air Flow Research 225s, don't always make sense for street use unless you're building one heck of a stroker. If displacement is modest, such as 289 or 302ci, and you're building for the daily commute and occasional weekend fun, more conservative castings such as the Edelbrock Performer or AFR 185 are adequate. Lower-displacement small-blocks like the 289 or 302 get by nicely with 1.94/1.60-inch valve sizing. Larger engines, like the 351W, will do fine with 1.94/1.60 or 2.02/1.60-inch valve sizing. Stroke any of these engines to 347, 408, or 427ci and Victor Jrs. and such make more sense. It is always important to remember displacement, regardless of what engine it is based on. You may have a 302 or 351W-based block. But, if you've stroked 347 or 427 ci into the 302 or 351W, you have big-block displacement. It's no longer small-block sizing you are dealing with. Head selection has to go accordingly.

JMC Motorsports Quick Tip:
Conservative port sizing for street, large ports for high-rpm race use. On the street, you need smaller ports, with greater velocity for good, low-end, traffic-light grunt.

Choosing The Wrong Cam

Proper cam selection has never been easy for novices. Much of the time, they choose too much cam or too little, or they choose a cam with screwball valve timing events that don't have much to do with lift or duration. They wonder why the darned thing doesn't come on strong at 5,000 rpm-or, it goes like gangbusters at five grand and is a snore down low coming onto the freeway.

Proper cam selection for your application takes a lot of homework and a bunch more study hall. How will a particular cam work with your intake manifold and head combination? What carburetor do you intend to use, or will it be fuel injected? What about headers and the exhaust system? Pipe sizing? Will cam profile provide sufficient intake-manifold vacuum at idle to run vacuum accessories such as power brakes, air conditioning, and more? How do you intend to drive the vehicle most of the time?

If you visit Comp Cams' Web site, you can get help selecting the right camshaft. Better yet, call Comp's tech line and chat with a pro about your Ford-what manifold, carburetor, and heads you intend to use-exhaust system, headers, and how you intend to drive your car most of the time. These folks can help because they are also performance enthusiasts. Aside from knowing cams inside and out, they can get you dialed into the right cam.

Another terrific source for information is Marvin McAfee at MCE Engines, known affectionately as "Dr. McAfee" for his keen ability to dial in just the right combination of parts to achieve spot-on results.

Gasket Selection

Gasket selection used to be simple because there weren't that many variations. Today, it's complex because there are so many types out there. Our advice here is simple-spend the money on better gaskets and save time (and money) in the long run. Buy the best gaskets you can get your hands on, such as Fel-Pro Print-O-Seal head and intake manifold gaskets. Invest in steel-reinforced urethane oil pan and valve-cover gaskets for exceptional sealing. They will cost more, but they're worth every penny invested for what they keep off your garage floor and driveway. What's more, you won't have to do the job over again.

JGM Quick Tip:
Don't opt for cheap stuff when shopping for gaskets. The thrill of a low price is forgotten when coolant is found in the oil.

Gasket Installation

We don't always treat today's high-tech gaskets the way they should be treated. We still throw all kinds of sealers and coatings on gaskets that don't call for anything outside of simple gasket installation and proper torque. For example, Fel-Pro Print-O-Seal gaskets don't require sealer-just a clean installation and recommended torque. Yet, too many of us apply silicone sealer just for extra measure. Don't do that. These gaskets already have help from the factory. One exception is intake-manifold-gasket cooling passages. If they are pitted at gasket contact surfaces, try a thin bead of high-temp RTV silicone sealer around cooling passages before gasket installation.

Cork gaskets require little sealer of any kind-just a super-thin film to close any gaps and maintain gasket positioning. If you torque valve covers, oil pans, and other engine components to the manufacturer's specified torque, you won't have to worry about leakage. Overtorque a valve cover or oil pan and you can count on leakage because it causes warpage, imperfections, and leakage.

Newer steel-reinforced urethane gaskets get the same treatment as cork and rubber gaskets except for the sealer part. Do not put sealer on these gaskets. Torque them to manufacturer's specifications.

Trans Am Racing Quick Tip:
Follow manufacturer's directions on gasket torque. Valve covers and oil pans don't need much. If gasket squish occurs, you are overtorquing.

JGM Quick Tip:
Absolutely never overtorque intake-manifold bolts. Follow manufacturer's torque specs to the letter. Always retorque, but never beyond specs. Overtorquing will lift cylinder heads and cause head-gasket failure.

Intake Manifold Selection

This has become cliche because we see it so often. Readers complain of no low- to midrange torque, and doggish performance coming out of a traffic light or onto the interstate. When we ask about their induction choice, we hear "Edelbrock Torker" or "Weiand X-terminator"-which clears up the mystery immediately. These are terrific race-only, high-rpm, single-plane manifolds. Single-plane manifolds do their best work when you're huffing a lot of air through them.

Proper manifold selection is simple. For the street, use a dual-plane manifold; for drag racing or road racing, use the single-plane. Why? Because each type of driving mandates a different kind of induction setup. Depending on the type of racing you intend to do, you may need a dual-plane if lots of low-end torque is needed coming out of a turn. You will just need larger runners like we find on the Edelbrock Performer RPM, Weiand {{{Stealth}}}, and even some of the older high-rise manifolds like the Edelbrock F4B or Buddy Bar Cobra manifolds.

Dual-plane intake manifolds have long intake runners, which help low- and midrange torque. Long runners contribute to increased air velocity at lower rpm, which gives torque down low. Making those runners larger helps velocity and volume at higher rpm.

Single-plane manifolds have shorter runners and a straight shot into the intake ports. This works best at high rpm because that's where we get velocity through these shorter runners. We have to spin the engine high to get air speed (velocity) through the ports.

Proper manifold selection is also a matter of choosing the right single- or dual-plane manifold because not all of them yield the same performance. Runner and plenum design directly affect performance on the street and on the track. Study runner and plenum design, port sizing, and port-alignment issues before selecting an intake manifold. Even though manifolds may look similar from one manufacturer to another, there are finite differences that make a difference in performance.

JMC Motorsports Quick Tip:
When buying an intake manifold, shop port sizing compared to your cylinder-head port sizing. Even though two manifolds from Edelbrock and Weiand may look the same, there are subtle differences. Get port sizing close on both.

Block Overbore

In our quest for displacement, sometimes we take our blocks too far. Each engine family has its limits when it comes to bore sizing. All factory small-block Ford blocks (221, 260, 289, 302, 351W) should be bored no further than 0.040 inch over the standard 4.000-inch bore. If you are going racing, this maximum should be no more than 0.030 inch oversize. Although some builders take them to 0.060 inch oversize, it is foolish. Marvin McAfee tells us a 0.060-inch overbore is courting disaster. FE big-blocks can go to 0.060 inch oversize because they aren't thin-wall castings like the 289/302/351W and Cleveland small-blocks. For those of you with 385-series big-blocks, going to 0.060 inch oversize is risky because these are also thin-wall castings. At the very least, sonic-check your 429 or 460 before considering a 0.060-inch overbore. We stress this due to core-shift issues.

When you overbore, keep compression ratio in mind. Whenever chamber size and piston-deck height remain the same, overboring will drive compression higher because you are squeezing more volume into the same space. Pushing an overbore to the limits of a block's envelope is risky business because you risk cylinder-wall failure. Aftermarket blocks have their own overbore maximum measurement, too, so be sure to not exceed that if using an aftermarket block.

MCE Quick Tip:
Before machine work begins, pressure test and/or Magnaflux your block to check for cracks. All the best machine work in the world is meaningless if you have a cracked casting.

Valve Sizing

John DaLuz of JMC Motorsports in San Diego, California, shares this one. As with carburetors, cylinder-head port sizing, and header tube size, valve sizing is another one of those situations where bigger isn't always better. Rule of thumb is simple-no larger than 1.94/1.60 inches (intake/exhaust) for 221, 260, 289, and 302 engines for street use. Larger 2.02/1.60-inch valve sizes work for 289/302ci engines with closer examination of valve-to-piston clearances, and valve-to-cylinder wall clearances. Larger 2.02-inch intake valves make sense when the chamber and cylinder wall don't shroud the valve. To make the right decision, look at all cylinder-head designs and options available.

If you are considering larger valves, ask yourself if they will yield any benefit. Is the larger valve size shrouded? If so, how can you expect improved airflow? Flow-bench testing shows time and again that larger valve sizing doesn't always improve air flow because a shrouded valve can suffer from airflow shortcomings throughout its travel. Bigger valves don't always net bigger power.

Mismatched Components

When a customer comes to MCE Engines with an engine project, Marvin McAfee asks what he wants the engine to do most of the time. McAfee subscribes to a strict regiment of proper parts selection and compatibility in every engine he does. He says customers come to him with collections of parts seeking an estimate, but he won't do an engine unless he is certain all of the parts will work well together. As a rule, he prefers to select and acquire the parts, clearing all phases with the customer as he goes.

Expect disappointment when you top an intake manifold with a carburetor ill-suited to the displacement, manifold, heads, and driving conditions expected. Anticipate trouble when you fit an aggressive cam to a block topped with incompatible heads with soft valvesprings. Figure on lackluster performance when you opt for a mechanical distributor for the daily commute that doesn't have a vacuum advance. Plan your engine build like you would your career or a dream home. It all has to work well together or you're wasting both time and money.

Before buying anything or even choosing an engine, know exactly how you're going to use it most of the time-then plan each phase of your engine build with liberal doses of common sense and patience. It's easier to wait on buying parts than it is to be sorry later when you've made a bad decision.

Measure Twice-Cut Once

MCE Engines takes a methodical approach to every engine it builds. This means inspecting and measuring at least three times during mock-up and assembly phases. Measuring once is courting trouble, according to McAfee. It's too easy to misread a micrometer or dial-bore gauge. Go back and measure again later to ascertain precise measurements. Write them down on the first pass, then write them down again on the second and third passes. And remember, you should be able to turn a crankshaft using two fingers with all eight pistons and rods installed. The weight of a 11/42-inch breaker bar alone should turn the crank before pistons are installed. If it just hangs there, clearances are too tight.

Too Much, Too Little Endplay

Crankshaft endplay doesn't get checked enough during engine builds, in our estimation. We've seen enough of them where we had to remind the builder to check. Trust your parts, but verify dimensions always, even with new components. Too much crankshaft endplay can bite you in the butt just as badly as too little endplay. Much of it depends on how you intend to use the engine.

If you're going with a manual transmission, clutch engagement and disengagement causes the crankshaft to ride the thrust bearing-on the clutch, off the clutch. The result is wear every time you step on the clutch. The more endplay you have, the harder shifting is on the thrust. Step on the clutch and the crank rides the thrust bearing hard. Minimum crank endplay is 0.004 inch. Maximum is 0.008 inch regardless of whether you are running an automatic or stick.

Another important item that is rarely checked is camshaft endplay-again 0.004-0.008 inch maximum. Excessive camshaft endplay leads to timing-set failure, lifter damage, and other unthinkables.

Ignition Curving

Here's one we see all the time. Did you know improper ignition tuning not only adversely affects performance, but it also can do permanent engine damage? Here's why: Ignition timing isn't just about aiming a timing light and getting 6 or 12 degrees BTDC timing at idle. What really counts is total timing and how it synchs with engine rpm. Total timing, meaning total spark advance in degrees of crankshaft rotation/position, should be completely in by 3,000 rpm.

As a rule, total timing should never exceed 36 degrees BTDC at 3,000 rpm and higher. Some people push the envelope and crank a few extra degrees in there thinking it will net us more power. But, when you dial in too much timing, you run a high risk of serious engine damage from detonation/spark knock. This happens when fuel ignition occurs too early on compression/ignition stroke.

The objective is to light the mixture at exactly the right time as the piston rises in the cylinder to where combustion is fully underway when the piston reaches top dead center. This hinges on fuel octane rating, ambient temperature, humidity, cam profile, chamber size and shape, air/fuel mixture, and atmospheric pressure (or pressure altitude). Every situation is different, which means no two engines will respond the same way to ignition curve. What works on your buddy's 302 likely will not work on yours.

And remember something else: Total timing when the engine isn't under a load is different than total timing with a load. With a load, you often need less timing because detonation typically occurs heavy load at wide-open throttle at low rpm. This calls for retarding total timing one degree at a time.

MCE Quick Tip:
Power begins to fall off with small-block Fords at 32 degrees BTDC. McAfee advises 34-36 degrees BTDC total timing.

Carburetor Tuning

Carburetor tuning can make or break an engine as much as ignition timing. A lean mixture can fold an engine over as quickly as early spark timing. This is why carburetor tuning is crucial to not only performance, but also to engine life because air/fuel mixture affects combustion temperature. A lean mixture raises temperatures. A rich mixture lowers temperatures. Lean mixtures and high temperatures place undue stress on piston crowns and ring lands.

This is why a spark-plug reading is important to carb tuning. The whiter the porcelain firing tip, the leaner the mixture. You want a porcelain tip that's tan in color. Sooty black is too rich. Jet size up for a richer mixture, and down for lean one step (jet size) at a time. It's a good idea to keep a jet kit handy for carb tuning. This allows you to swap jets anywhere you go. Hard acceleration at wide-open throttle with a clean shut-off is the best way to do a plug reading. Take it out for a blast, listen for pinging (spark knock), and do a plug reading afterward. This not only determines fuel mixture, it also determines spark-plug heat range. Examine the spark-plug cross electrode to determine heat range. If the cross electrode has particles, is blue, or appears burned, it's too hot. Normal color means proper heat range.

MCE Quick Tip:
If you're going racing (repetitive wide-open throttle), consider the next lowest spark-plug heat range. Also consider richer jetting in steps. Holley jetting, for example, increases fuel flow by 4 percent per the next largest jet size.

Cleanliness Is Next To . . .

We are always shocked at how many engines we see in shops that are not properly protected against dust. Those of you in desert regions understand dust because it's a part of daily life. We're always dusting furniture in the West. However, those of you in humid, rainy regions also have to consider dust because it exists everywhere in one form or another. Flaking human skin and hair generates dust particles, as does the simple decay of just about everything from free radicals in the atmosphere.

Keep your engine bagged, plugged, and covered whenever you're not working. You don't have to spend a lot of money on engine plug kits. Use paper towels, duct tape, whatever it takes to keep dust and moisture out. Paper towels, for example, will absorb moisture, which makes them a good idea. And during assembly, clean all parts thoroughly. Dust particles will eat the life out of new bearings, pistons and rings, cylinder walls, oil pump cavities, and more.

MCE Quick Tip:
Never operate an engine without an air filter-ever.

Dry Idea

Another shocker is engine builders who use assembly lube between bearings and blocks, and bearings and rods. Surfaces between bearings and saddles must be completely dry because it is the saddle's job to secure the bearing. Simply put, you don't want the bearing to turn in the saddle or connecting rod journal. You want a soft crush on the bearing, coupled with the security only dry surfaces will yield.

MCE Quick Tip:
Assembly lube goes on bearings only after installation and the bearing is fully seated.

Engine Won't Start?

How many times have you turned an engine over in vain attempts to get it to light off? Check your ignition coil to ascertain proper connection of the positive and negative terminals. Positive from the car's wiring harness-negative to the ignition points or module inside the distributor. Another item that nails us from time to time is the two terminals on the starter solenoid. When we get those backwards, the starter will turn over immediately when we turn the ignition switch to "on." Brown wire to "I" and blue with a red stripe to "S." "I" provides 12 volts to the ignition during cranking (instead of passing through the resistor wire). "S" latches the starter solenoid (electromagnet) to get battery power to the starter. One more thing, did you connect the ground strap between the engine and firewall?

MCE Quick Tip:
Did you put fuel in the tank?

Exhaust valveguide to stem clearances

Valve stems cease when clearances are too tight and engines get hot. By the same token, oil gets past the stems and guides when tolerances are too loose. Valve-stem-to-guide clearance should be no tighter than 0.002 inch on the exhaust side and 0.0015 inch on the intake side.

JGM Quick Tip:
Check stem-to-guide clearances with great care. Exhaust-valve stem-to-guide clearancing is especially critical due to extreme heat.

Oil Pump PickUp To Pan Clearance

JGM reminded us of this one, and we see it time and again-oil-pump pickups that touch oil pans. Most of us never check this one. Just because there's oil in there doesn't mean the pickup won't chafe. Pickups need to be close to the sump bottom, but no closer than 31/48-inch minimum.

Using Synthetic Engine Oil For Break-In

Synthetic engine oils are terrific forms of engine lubrication because they offer unequalled protection for moving parts. But when breaking in a new engine, plain, old-fashioned, mineral-based petroleum SAE 30-weight is what you want. Regular SAE 30-weight engine oil allows piston rings to properly seat during run-up because it offers a different kind of lubricity than synthetic oil. Synthetic engine oil has a different molecular structure than regular engine oil. During break-in, piston rings need better cylinder wall contact only regular engine oil can give them for proper seating. Once the rings have seated (around 500-1,000 miles), switch over to synthetic and enjoy long engine life.

MCE Tip:
Always hand-fill the oil filter before installation to keep a solid oil wedge during start. Empty filters on start-up ultimately damage bearings.

Not Port Matching Intake Manifold, Heads, Gaskets



Mark Jeffrey of Trans Am Racing mentioned this one. We don't understand this mistake because it's so obvious. Never assume cylinder-head and intake-manifold ports automatically line up, because they don't-not even when cylinder heads and intake manifolds are from the same manufacturer. Regardless of the performance you are seeking, always port-match cylinder heads and intake manifold. Port-match using gaskets on both manifold and heads. When port-size difference is significant, consider the selection of more compatible heads and manifold. Large manifold ports and small cylinder head ports (and vice versa) don't make sense because it robs power and creates disturbed airflow through the runners.

Getting Head Gaskets Backwards On Small-block Fords



Got an overheating problem you can't figure out? Small-block Ford cylinder-head gaskets can be installed backwards, which is an automatic overheat because head gaskets installed backwards cut off coolant flow to the back of the block and heads. Install one head gasket backwards and you have a hidden overheat issue. Hidden because the engine runs a pinch hotter but doesn't boil over. But because coolant flow isn't reaching the back of the block and head on one side, damage is being done you're unaware of until an exhaust valve fails or pistons crack on that bank.

"FRONT" means FRONT with all cylinder head gaskets, even if it doesn't look right. Position "FRONT" at the front, and make sure coolant passages are at the rear of the block. While you're at it, check for proper steam-hole positioning, too. Sometimes head gaskets come from the factory missing important passages.

JGM Quick Tip:
Pitted block decks and heads are unacceptable. Check cooling passages for corrosion pitting, which can cause coolant leakage. If there's pitting, you need to mill heads and/or decks. If they cannot be milled, replace the casting.

Not Chasing Threads

MCE Engines chases bolt holes and threads on every engine it builds because burred, damaged, and dirty threads yield erroneous torque wrench readings. Clean threads are key to proper torque readings and application. McAfee chases threads on all bolt holes and dresses all bolt threads for smooth installation and accurate torque application. When you don't chase threads, the resistance felt at the torque wrench is actually resistance at the threads, not the assemblies you wish to mate. Chase threads, then lubricate them with molybdenum grease for smooth torque application.

Not Deburring Sharp Edges

Deburring is a crucial step in engine blueprinting. In fact, if you don't deburr, you're not blueprinting. Deburring is the removal of sharp edges (also known as stress risers) that can lead to material failure. High spots and edges create weak points that become cracks. Deburr every part of your engine-block, heads, connecting rods, crank, lifters, camshaft, and a host of other spots.

Not Dynamic Balancing

Most machine shops and engine builders have dynamic balancing as an option. But to Mustang & Fords, dynamic balancing and extreme attention to detail are mandatory steps in an engine build. Dynamic balancing is crucial to engine smoothness and survival because vibration (any vibration, no matter how small) kills. It shakes things to pieces. Not balancing an engine is foolish, courting disaster at worst and shortening engine life at best.

When you dynamic balance an engine, you balance the crankshaft (just as you would tires and wheels) for smooth operation. Then, you balance connecting rods and pistons to match the crankshaft balance. Do this every time you build an engine.

JMC Motorsports Quick Tip:
Take dynamic balancing to extremes and have your balancer checked, then recheck the overall balance before wrapping it up. It pays to check everything two to three times.

Not Prelubing The Oil System

Although most reputable engine builders know to lubricate moving parts with assembly lube, it is wise never to chance firing an engine without first doing a pre-lube. Pre-lubing is the process of filling the oil pan with SAE 30-weight oil and spinning the oil pump with a pre-oiler to prove out oil pressure and flow. When you don't pre-lube, you risk a dry start-up, which can do permanent engine damage in a matter of seconds.

Trans Am Racing Quick Tip:
Pre-lube using straight SAE 30-weight engine oil with both valve covers removed. Check for oil flow from rocker arms. Oil flow should be a healthy volume. Expect to see traces of assembly lube and moly-coat in the oil.

Not Setting Distributor Shaft EndPlay

MCE Engines stresses always checking distributor-shaft endplay and block clearances. Like crank and cam endplay, distributor-shaft endplay can be a player in engine failure. Too tight or too loose and you can expect cam and distributor drive-gear failure.

Distibutor shaft endplay is commonly overlooked when engine building.

Not Checking Oil Pump To Crank Clearances

Aftermarket oil pumps and stroker kits have created a new challenge for engine builders-oil-pump-to-crankshaft-counterweight clearance problems. This clearance problem nails you whenever you don't make sure there's at least 0.060 inch clearance between the oil pump and counterweight. We stress the 0.060-inch minimum clearance because as engines get hot, parts grow. It may clear by a whisker when cold, and hit when it's hot. Keep at least 0.060 inch between the crank and pump, and stay safe.

JGM Quick Tip:
When checking pump-to-crank clearances, closely examine the pump through 360 degrees of crankshaft rotation. Minimum clearance is 0.060 inch throughout.

Steel Distributor Gear For Roller Cams

It's a popular misconception that roller cams require a special kind of distributor drive gear, but it's simpler than that. Flat-tappet camshafts are made of iron and call for the use of an iron gear. Roller camshafts are made of steel and call for distributor gears with the same hardness, either steel or bronze. Of the two, steel is preferred over bronze because it lasts longer. Use an iron distributor drive gear with a steel roller camshaft and you can expect failure. The steel shaft will eat an iron gear alive, with iron particles finding their way to your oil pickup.

Overtorquing-Not Torquing Everything

Did you know you should torque every fastener with a torque wrench? Fastener failure is one of the single greatest reasons behind engine failure, caused by improper torquing. From brute main bearing caps to valve-cover bolts, all fasteners should be tightened to recommended torque specifications. Why torque wimpy little valve-cover bolts? To give gaskets proper crush and seal effectiveness, and to prevent bolt breakage. Use a torque wrench on every fastener.

MCE Quick Tip:
If torque specs cannot be found in your Ford Shop Manual, check bolt size torque specs in a Motors or Chilton repair manual. Every bolt should be torqued with a torque wrench for accurate gasket compression and bolt stretch.

Using Stock Oil-Pump Shaft

Engine builders who can build 600hp small-blocks then insult the message with a spaghetti-thin stock oil-pump shaft stun us. We will say it again-never use a stock oil-pump shaft in your engine build. Opt for an ARP shaft that offers brute strength and added security. Shaft failure equals immediate engine failure.

All-Builders-Agree Quick Tip:
Never use a stock oil-pump shaft-not even in a stock engine.

Not Checking Pushrod Length/Rocker-Arm Geometry

This is an easy mistake to make as enthusiasts tend to install everything right out of the box because it's new. But new doesn't always make it right. Pushrod length and rocker-arm ratio directly affect where rocker-arm tips will sit on the valve stem. You want the rocker tip to sit squarely on the valve stem tip at one-half valve lift to where there is no side load on the stem. Not enough of us get that one right because we don't want to wait for the correct pushrod or rocker arm. Getting this one wrong can lead to valvetrain and engine failure.

MCE Quick Tip:
Always check rocker arm to stud/fulcrum clearance when using a high-lift camshaft. Also check rocker arm to valvespring retainer clearance. In both instances, a minimum clearance of 0.060 inch is what you want.

ValveSpring Coil-Bind Check

Valvespring coil bind happens when there is more lift than the spring can accommodate. This can (and will) lead to valvetrain component failure-bent pushrods, broken keepers and retainers, and a host of other surprises. If you don't check for valvespring coil bind, you do so at your own peril. The closest the coils can be is 0.060 inch at full valve lift.

All-Builders-Agree Quick Tip:
Not checking this one, even with a mild cam, can bite you in the butt. Coil bind will do serious engine damage.

Knocking Freeze Plugs Inside Block/Heads

Some mass rebuilders make this mistake because they make money moving at a fast pace. Disassemblers tend to knock freeze plugs inside the block and heads to save time. The problem is, freeze plugs inside water jackets inhibit coolant flow and create hot spots. If you have an overheating problem you cannot solve, check your water jackets for old plugs.

Collective-Sigh Quick Tip:
Inspect water jackets for freeze plugs and other debris in all situations, even when the block has been cleaned and looks sanitary. Hidden debris can cause overheating.

Not Sonic Checking Cylinder-Wall Thickness

It's a good idea to sonic check all engine blocks prior to building. Sonic checking an unknown block clears up any doubt and gives you a good idea of how far you can bore. Sonic checking determines cylinder-wall thickness and integrity. Few things are more discouraging than engine failure because you didn't check.

JMC Motorsports Quick Tip:
Why sonic check? Because core shift in the block can happen under the best of circumstances and a sonic check will find it. Even a 0.030-inch overbore can bite you when core shift is extreme.

Not Using High-Temp Sealer On Freeze Plugs

All builders concur: Freeze plugs can pop out when you don't use a high-temp sealant and proper installation technique. A high-temp sealer, coupled with using the right plug and installation technique (getting the plug flush), makes the installation secure. Some builders install screw stops around the plug perimeter if revs-and freeze-plug failure risk-become high.

Using the 2/60 Rule

Marvin McAfee subscribes to the 2/60 rule on every engine build when specifications are not available: minimum 0.002 inch and 0.060 inch clearances. The 0.002-inch rule applies to bearing clearances, lifter bore clearances, run-out, distributor-gear backlash, and more. Clearances like valve to piston, rocker arm to valvespring, oil pump to crank, and the like get the 0.060-inch minimum rule.

28 ounces versus 50 ounces

We've seen this one time and again. Small-block Fords, which are externally balanced, have a given offset balance that mandates a compatible harmonic balancer, crankshaft, and flywheel. Offset balances are 28 and 50 ounces, respectively. Prior to 1982, 302ci engines had a 28-ounce offset balance, which exists outside of any dynamic balancing you may do during an engine build. When reciprocating mass weight increased in 1982 with the 5.0L High Output engines, offset balance increased to 50 ounces.

The mistake comes when you install a 28-ounce balancer or flywheel on a 50-ounce offset balance crankshaft, and vice versa. When you are amassing parts for a small-block Ford, remember the 28/50-ounce difference. It will save you a lot of grief.

Piston Rings Installed Upside Down

This one rears its ugly head the minute you fire the engine. Piston rings are shaped the way they are for a reason. Although it is a popular misconception that both upper rings are compression rings, nothing could be further from the truth, according to McAfee. He tells us only the top ring is the compression ring. It is modified (machined) at the top inside the ring groove to keep the ring from rolling down when exposed to hot gasses. This allows the ring to maintain sealing at the piston crown. The second ring is an oil-control element designed to meter oil up the cylinder wall. The more traditional oil rings in the third groove are oil scrapers. They carry oil down the cylinder wall and into the piston's interior for cooling purposes.

Piston rings have chamfers to provide a specific function, and are made of certain materials, also to provide a specific function. That's why you don't want to install them backwards, nor in the wrong groove. Follow the manufacturer's instructions closely and always use a ring installer. Do not roll rings into grooves (even though everyone does it). It is impossible not to warp piston rings when you roll them on because they are not spring material. They will remain warped.

MCE Quick Tip:
Always use a piston-ring installation tool. No exceptions.

Not Enough Connecting-Rod Side Clearance

This one can stop you cold. Connecting-rod side clearances don't get the attention they deserve. Remember, rod journals are the hottest spot in your engine short of exhaust valves, stems, and seats. Oil temperatures in this area can run upwards of 400-450 degrees F. This is why rod side clearances are critical to engine survival. They should be 0.015-0.025 inch. Rods become a throwaway at 0.028 inch side clearance.

MCE Quick Tip:
Oil is not only a lubricant, it is a coolant. Clearances that are too tight limit oil flow off the bearings, which limits cooling.

Not Measuring Piston-Ring Clearance, End Gap, Side, Back . . .

It's easy to overlook piston-ring clearances. Most people think it's a matter of checking end gaps and popping those little guys in place. But did you know you need to check piston-ring side and back clearances? Checking these clearances and making sure you have at least 0.002-inch clearance in back and at the sides prevents ring bind and breakage.

Line Boring The Block

Although shops widely recommend line boring when bearing saddles are out of alignment, you need to avoid line boring whenever possible. Line boring puts the crank and cam closer together, which causes slop in the timing set and irregular valve timing. Unless you are dealing with an expensive block or a matching number block you want to keep, avoid line boring.

MCE Quick Tip:
Line honing removes less iron/aluminum than line boring. Line hone first.

Laying A Crank On Its Side

Absolutely never lay a crankshaft on its side-not even for a few minutes. Crankshafts should always be stored standing straight up or hanging from a storage fixture. Laying a crank on its side will cause permanent damage.

Not Enough Pushrod-Hole Clearance

Pushrods should never rub the cylinder head, yet a lot of them do. Minimum pushrod clearance should be 0.060 inch.

Not Checking Cylinder-Head And Block-Deck Warpage

We learned the hard way how important it is to have a machine shop check for block-deck and cylinder-head warpage. When MCE Engines was doing our Summit Racing 331 Stealth engine project, the brand-new For Racing Sportsman block's deck was 0.017 inch out, which means cylinder heads and intake manifold would have wobbled. McAfee cut the deck, removing a 0.017-inch irregularity that would have created serious problems later on. All blocks and heads, old and new, must be checked for warpage and poor initial machine work before machine work begins.

Faulty Rear Main Seal Installation

Rear main seals should never leak, yet they do when not properly installed. When installing a two-piece rear main seal, the seal lip should point inward towards the front of the block. Seal end gaps should be located not at the main cap parting lines, but slightly away from them with a small dab of sealer at each gap. Use sealer between the seal and block grooves. One-piece seals follow the same rule, with the seal lip pointed toward the inside, and sealer between the seal and block.

JMC Motorsports Quick Tip:
Use high-temp RTV silicone sealer between the No. 5 main cap and block to ensure sealing.

MCE Quick Tip:
Don't install rear main seals backwards. The seal-to-crankshaft lip must be angled inward toward the crankcase to be effective. Otherwise, count on plenty of oil all over your driveway.

Improper Valve Lash

Jim Grubbs of JGM tells us valve lash gets set improperly most of the time because many people don't understand how it works. It's a good idea to follow firing order when you adjust valves to make sure none get missed. Every builder has their own technique. Some adjust valves in quarter crankshaft turns. Some go bank by bank-watching the intake valve open and close-then checking lash.

Although few of us use mechanical cams these days, especially on the street, valve lash is typically 0.010-inch intake and 0.020-inch exhaust depending on application. See the manufacturer's specifications for details. With the cam lobe at base circle (valve completely closed), the thickness gauge should glide between rocker tip and valve stem without binding. Check to see if valve adjustment happens with the engine hot or cold.

For most of us with hydraulic camshafts, follow firing order, watching the intake valves open and close one cylinder at a time. As the valve seats, jab the starter quickly one more time. It's a good idea to see if the piston is at top-dead-center. Loosen the adjustment nut or poly-lock until you can turn the pushrod with finger and thumb. Twirl the pushrod and slowly tighten the nut. Once you can't twist the pushrod anymore, tighten the nut 11/44-11/42 turn. In some instances, 11/44 turn isn't enough and you will have rocker-arm noise. Most of the time, 11/42 turn is ideal. Some manuals suggest 31/44 turn. In our opinion, that is too much and could cause valve-to-piston contact at high rpm if lifters pump up.

JGM Quick Tip:
When tightening poly-locks, begin with the Allen screw. Snug the nut after tightening the Allen screw. If you overtighten the nut after tightening the Allen screw, you could crack the poly-lock.

Distributor Drive-Gear Fit

Distributor-shaft drive gears should always be a pinch fit, meaning the gear should have an ever-so-slightly smaller inside diameter than the shaft. This is necessary because the distributor drive gear has oil-pump load to deal with outside of just spinning a rotor. A good pinch fit, coupled with solid roll-pin integrity, should keep you in the clear. Some aftermarket distributors offer a loose distributor gear-to-shaft fit, or at the least a slide-on fit. This is unacceptable and could cause major engine damage if the roll pin fails.

MCE Quick Tip:
If distributor drive gear-to-shaft fit is loose, do not use the distributor. Try another gear and check fit. If the same problem exists, discard the distributor or replace the shaft.

Nitrous or Supercharging Without Proper Planning

Nitrous and supercharging can be costly mistakes if you don't do your homework beforehand. If you're contemplating quick, cheap power gains (nitrous-oxide injection), you must first know what's inside your engine. Cast or forged aluminum pistons? Cast pistons? Forget it. Forged? Good-you are cleared to proceed to the next step. What is your engine's compression? Don't know? Then you better check now.

When manufacturers assure you 100, 150, 200 bolt-on horsepower increases by touching a button, sacrifices will be made elsewhere. Your engine will not live as long. Nitrous introduces your engine to a violent jolt of extreme heat energy hammering the piston crowns, rings, and lands. Rod bearings also take a pounding with nitrous.

The same rules apply to supercharging, which isn't quick, nor is it cheap. It's just more subtle than nitrous, and mandates special care. Remember, there are no free lunches in the world of power. When you gain big one way, you make huge sacrifices somewhere else.

MCE Quick Tip:
Any power adder will require an upgraded fuel system.

Not Checking Spark-Plug-Wire Resistance

Spark-plug wires get the same kind of attention rear axles do-not enough. If your engine is plagued with misfire or sluggish performance, check each of the spark-plug wires for resistance and external voltage leaks. If you see them arcing in the dark, or you have cracked and split insulation, they need to be replaced. Resistance to the flow of high-energy electricity will cause a weak spark or none at all. A spark-plug wire that shorts to ground (arcing you can see or not see) doesn't allow current to flow to the spark plug. If it shorts to ground, there isn't sufficient spark at the plug to get the job done. Borrow or buy a volt/ohmmeter and check your spark-plug wires for resistance from the distributor cap to the spark plug. While you're at it, inspect the distributor cap for cracking. No more than 4,000 ohms of resistance to current flow anywhere-including the distributor cap. Anything greater than 4,000 ohms of resistance is a throw-away.

Reusing Old Gaskets

Some types of gaskets can be reused repeatedly. Cork gaskets should be replaced every time you open the engine. Ditto for cylinder-head and intake-manifold gaskets. Reusing intake and cylinder-head gaskets is courting trouble. Can you afford to experience coolant in your oil? Why take chances? Replace the gaskets.

MCE Quick Tip:
Gasket in a tube is not recommended. There is no substitute for good gaskets. A word on Permatex Form-A-Gasket-great stuff that offers great sealing, but cleanup is difficult.

Applying Coatings To Head Gaskets

Today's cylinder-head gaskets don't need spray-on coatings or sealers. Install them dry and torque in sequence to proper specifications. Some head gaskets require a retorque after a full heat cycle; some do not. Read and follow the manufacturer's instructions to the letter.

MCE Quick Tip:
Wear gloves or wash your hands before handling gaskets. Skin oil will contaminate gasket surfaces.

Cheap is BAD!

Engines fail because of poor workmanship, but also when we choose to do it on the cheap. Cut-rate products are cheap because they aren't up to the same standards as the more expensive stuff. When you buy antifreeze that's a couple of bucks a gallon cheaper, there's a reason it's cheaper. It may have fewer additives, or lesser-grade additives, even though it's green like the higher-cost brands. The same can be said for engine oil, gaskets, seals, bearings, piston rings, pistons, hardware, valves, and the rest of it. Be smart and spend the money going in on better parts rather than suffer the consequences of engine failure later.

MCE Quick Tip:
Before building an engine, practice the three "T"s-time, tools, and technical information.

Another MCE Quick Tip:
Never use a steel/iron hammer. Always use a soft metal (brass) hammer or mallet.