This chapter is dedicated to good, solid, reliable engine building technique. Producing this book and others here in Southern California, we’ve been in the company of some of the best engine builders in the world. One of them is John Da Luz of JMC Motorsports in San Diego. John has been building automobiles and the engines that power them for more than 25 years. He enjoys an extraordinary track record as a seasoned engine builder. His experience lives in virtually every kind of racing venue in the world, including top fuel.
This Tech Tip is From the Full Book, HOW TO BUILD FORD RESTOMOD STREET MACHINES. For a comprehensive guide on this entire subject you can visit this link:
SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://www.diyford.com/build-stroker-ford-small-blocks/
We have also had the good fortune of knowing Mark Jeffrey of Trans Am Racing in Gardena, California, who possesses a wealth of experience as a seasoned engine builder, most of it with Fords. These two gentlemen are going to show us the way to solid, reliable power from a small-block Ford.
Engine building technology has made considerable advances over the past 30 years. We’ve learned that it’s the small details that can make or break a project. The two biggest details we can think of are checking clearances and triple-checking your work. Far too many of us learn the hard way because we’re not attentive enough to detail. We learn when an overlooked rod bolt fails half way down the track. And we learn when a carelessly seated valve keeper escapes at high revs, destroying the piston and cylinder wall in less than a second. These are the important details we don’t want you to miss during your budget engine build.
Far too many engine projects fail because there wasn’t proper planning. Planning is the most effective enginebuilding tool you can have. We waste time and money when we don’t think about what we want the engine to do. Part of building an engine is knowing exactly what you can afford, then not giving in to ego and the temptation. And that’s the mistake a lot of us make along the way. We want to impress our peers. But these are the wrong reasons to build an engine. Don’t build an engine to impress anyone beside yourself, because you alone will have to live with the result.
Most of us overbuild our engines. We build more engine than our Ford needs, which costs unnecessary time and money. For example, you’re building a classic Mustang and you want it to be fast. You’re thinking of building a 351W stroker displacing 427 cubic inches. Future plans include fuel injection and a supercharger. Just imagine, the power of a big-block in a lightweight classic. Maybe it is more than your Mustang (and your driving skills) can handle. You don’t have to worry about impressing us. We’ve been there too. And we understand the drawbacks of overbuilding. This is why we’re sharing the cold, hard facts of engine building with you.
Too many enthusiasts build more engine than a car can safely handle. When we infuse big displacement power into a lightweight Mustang, Falcon, or Fairlane, we’re not thinking enough about the engine and vehicle as a package. Most of us get it backwards. We build a powerful engine, then we wonder how to manage all that power safely and effectively. Build the car first, then the engine, because too much power in an unprepared platform can get you killed. A well thought-out platform will have good brakes, a handling package, traction enhancement, the right tires and wheels, a rear axle that can take the punishment, and a mature driver who understands all of this.
Our goal is to teach you how to build a reliable engine that you can afford that will make the power you need. No matter what the formula is, one basic formula holds true. Performance level is tied directly to budget. The greater the budget and know-how, the faster you’re going to go. You’re not going to make a 600 horsepower smallblock for $2500. Keep your expectations and planning realistic. Then go work your plan with perseverance. Lets get started.
TOOLS OF THE TRADE
It is easy to get carried away in the tool department at any department store. That first trip to Sears is often like your first trip to the speed shop. You lay down the credit card and come home with a wealth of goodies. But they don’t always apply to building an effective engine. It is easy to waste money in all of the excitement.
We suggest Sears Craftsman tools because they have a lifetime warranty, a great reputation, and there’s a Sears store in nearly every area of the world. The Craftsman warranty is a no nonsense, no fine print warranty. Bust a socket and Sears will replace it with no questions asked. Strip out a ratchet and Sears will hand you a new one or rebuild your old one. Sears Craftsman tools are the best tool value there is. Yes, they’re costly going in, but they remain the best tool value going. The next best tool value going is Husky in the bang-for-the-buck department. You can find Husky tools at nearly any home improvement or hardware store for even less money than Craftsman, yet with the same no nonsense lifetime warranty.
Here’s what you need to get started:
- Set of Common and Phillips Head Screwdrivers
- Set of combination wrenches (1/4”, 5/16”, 11/32”, 3/8”, 7/16”, 1/2”, 9/16”, 5/8”, 11/16”, 3/4”, 7/8”, 15/16” and 1”)
- 3/8” Drive Socket Set (3/8”, 7/16”, 1/2”, 9/16”, 5/8”, 11/16”, 3/4”)
- 3/8” Deep Well Sockets (3/8”, 7/16”, 1/2”, 9/16”, 5/8”, 11/16” 3/4”)
- 1/2” Drive Socket Set (7/16”, 1/2”, 9/16”, 5/8”, 11/16”, 3/4”, 7/8”, 15/16”, 1”, 1 1/16”, 1 1/8” and 1 1/4”)
- 1/2” Drive Deep Well Sockets (7/16”, 1/2”, 9/16”, 5/8”, 11/16”, 3/4”, 7/8”, 15/16”, 1”, 1 1/16”, 1 1/8” and 1 1/4”)
- 1/2” Drive Breaker Bar
- Needle Nose Pliers
- Diagonal Cutting Pliers
- C-Clip Pliers
- Set of Vice Grips (and we mean Vice Grip brand only!)
- Set of Punches
- Small and Large Hammers
- A Five-Pound Sledge Hammer
- Torque Wrench (optional, but a great investment)
- Drill and Bits (spend the money and opt for high quality bits)
- Putty Knife or Gasket Scraper
- Hack Saw (use 24 teeth per inch for best results with metal)
- Magnetic Bolt Tray
- Large Top Chest or Heavy Duty Tool Box with drawers
This list is suggested to get you started and will last you the rest of your life with care. Tools are something you can pass along because, with proper care, they will last several lifetimes. Most of us buy socket sets, but we forget to go for the deep well sockets, which you will need in the course of an engine build. And one other thing – opt for six-point sockets, not 12-point. A six-point socket won’t strip a bolt head and provides a firm grip. Make sure your socket sets have at least two extensions – one 3-inch and one 7-inch. Spring for the universal adapter as well for easy access. If you can afford it, buy a matching set of 12-point shallow and deep well sockets because they do have a purpose with some engine applications.
When you’re shopping screwdrivers, hold them in your hand first. You want a screwdriver that feels good in your hand and offers adequate grip comfort and mechanical advantage. If your hand slips around the handle, then it is a poor design. The tip should be super tough tool steel that will not strip out or break. Cheap screwdrivers always strip out and break. Go the extra mile and invest wisely now in a screwdriver that will last you a lifetime. Another idea is to buy screwdrivers with bright orange handles for visibility and safety. This lessens the chance of leaving tools where they don’t belong.
We push the idea of quality tools because there really is a difference. Lowbuck wrench sets you can buy for nine bucks won’t get the job done effectively. A cheap forging or casting will strip out and leave you hanging on a Sunday afternoon when you need it most. With Sears Craftsman, Husky, MAC, or Snap-On tools, you get a lifetime warranty you can count on. And it’s a warranty that’s good for as long as the tool exists – for you, your child, your grandchild, great grandchild, and more. MAC and SnapOn tools tend to be very expensive and available only off a truck at better garages everywhere, which makes Craftsman and Husky better a better value and easier to find. Husky doesn’t get enough air-time, but it is one of the best bargains for the money. It costs less than Craftsman, Snap-On, or MAC, and you still get a lifetime warranty.
Proper tool care once you’ve made the investment is what assures you reliability from here on out. Keep your tools clean and serviceable. Lubricate ratchets periodically with engine oil or white grease for best results. Drill bits should be sharpened periodically. And when you’re using a drill, run the bit slow and keep it wet with lubrication while drilling. Drill bits begin to squeak whenever they’re dull. Invest in a drill bit sharpener or find a reliable shop in town that sharpens drill bits. Just about anyone who sharpens lawnmower blades and chain saws can sharpen your bits.
Know when it’s time to retire wornout tools. Tools that are not serviceable can be dangerous. A loose hammerhead, for example, could accidentally rearrange someone’s dental work. Cracked sockets, worn wrenches, busted screwdriver handles, stripped ratchets, and other forms of serious tool deterioration are reasons to invest in fresh equipment. Remember, it is about your safety and the integrity of your work.
Tools To Rent
These are the tools you’re going to use only during an engine build and probably won’t need again until the next build.
- Torque Wrench
- Piston Ring Compressor
- Harmonic Balancer Puller
- Valve Spring Compressor
- Freeze Plug Driver
- Seal Driver
- Thread Chaser
- Small Grinder (if you port your own heads)
- Easy Outs (for broken bolts in blocks and heads)
- Engine Hoist
- Engine Stand
- Dial Indicator
Torque wrenches typically are either beam or breakaway types. We suggest the breakaway type that clicks when the specified torque is reached. What’s more, learn how to properly use a breakaway torque wrench. Two things are important to remember about torque wrenches. Never use a torque wrench to remove a bolt or nut – ever. You will disturb the calibration. And secondly, never overtorque a fastener. When you torque a fastener, you are stretching the bolt stock. Too much torque and you stress the fastener. Specified torque readings are there to ensure fastener integrity.
Piston ring compressors are available in different forms. The most common type you will be able to rent is an adjustable type. There is also a ratcheting type that makes piston installation a snap. Custom sized billet ring compressors are costly and not for the novice.
Harmonic balancer pullers are a borderline rental item. This is a tool you may use again and again. They don’t cost that much to buy, which is what makes them a borderline item. Balancer pullers also make great steering wheel pullers. Look for the multi-purpose in any tool you’re thinking about renting. If you expect to use the tool again, it may well be worth the investment now.
There are two basic types of valve spring compressors – one you use in the shop on a cylinder head in the raw (looks like a huge C-clamp) and one you use with the head installed (more like a pry bar used only for ball/stud fulcrum rocker arm applications). For engine rebuilding, you’re going to need the C-clamp type. You can sometimes pick these up at a discount house for less than it would cost to rent one for several days.
Freeze plug and seal drivers are one of those borderline items you could use again and again. You can also use a likesized socket as a driver on the end of an extension. This saves money, but could damage the socket. Don’t be a tool abuser.
Thread chasers are a vital part of any engine build because you want clean threads. Clean threads yield an accurate torque reading when it’s time to reassemble the engine. It’s a good idea to chase every bolt hole. When a thread chaser is outside of your budget, use Grade 8 bolts and other fasteners with WD-40 to chase the threads. This may sound crude, but it will save you money and get the job done. What’s more, no one knows you did it but you will have clean threads.
Tools should be rented only at the time you intend to use them. Don’t rent every tool mentioned here at the same time because you’re not going to use all of them at the same time. Thread chasing, for example, should be performed when the block returns from the machine shop clean, machined, and ready for assembly. Machine shops that are on the ball will have already chased your threads. Remember that thread chasing is time consuming. Machine shops don’t generally do this unless asked and paid for the service.
Engine stands are one of those purchase/rent questions because renting can sometimes cost you more than simply buying, and engine stands can be cheap depending on where you buy. Harbor Freight Salvage has some of the best values going at $50 to $100 for a stand you will have for the rest of your life.
The decision to rent or buy tools boils down to how often you will use the tool and how long you will need the tool during your engine build. Any time you’re going to need the tool longer than 1-3 days, you’re probably better off buying. If you have to buy, look on the bright side. You can always loan it to friends or sell it after your engine is finished. Keeping it makes it a useful piece of community property among friends.
KEEP A CLEAN, ORGANIZED SHOP
We cannot stress enough the importance of keeping a clean, organized shop. Do your engine teardown work where you can catalog everything and keep it in its rightful place. Keep engine parts and fasteners in jars or plastic containers that are labeled with a marker. Haul the block, heads, crankshaft, and connecting rods to a machine shop immediately upon disassembly. This avoids any confusion and keeps you rolling. If you cannot afford the machine shop at the time, leave the engine assembled until you are ready. We speak from experience on this one because too much is lost both mentally and physically once the engine is disassembled. Keep disassembly, cleaning, machine work, and assembly as cohesive as possible.
It is always a good idea to keep an engine project organized from planning to completion. Know what you’re going to do and when you’re going to do it. Then get busy and see your engine project through to completion. Nothing’s more discouraging than a disassembled engine that’s going nowhere because you didn’t have a plan or the money.
When it is time to assemble the engine, you must have a hospital-clean environment. Even simple house dust (which is actually dead human skin cells, hair, and other forms of decaying matter) will damage an engine’s mating surfaces. House dust will score bearings, journals, and cylinder walls. We’re not kidding either. Whenever you’re not working on the engine, keep it covered inside a plastic trash bag. When you are assembling parts, clean them first with brake cleaner or compressed air to remove any dust. Avoid engine assembly on a windy day, which generates its share of dust. Automotive bodywork and sheet metal repair create harmful dust that will damage engine parts. Keep this kind of work away from your engine. If the gardener is out there mowing the lawn and edging the sidewalks, keep your engine covered. Make sure engine assembly lube and oil are pure and clean. Stray matter in either of these elements will damage your engine. Always keep one thing squarely in mind. Any kind of stray matter, no matter how small, will damage your engine.
When it is time for engine assembly, everything should be in proper order. Pistons should be matched to each bore. This means each bore should have been mic’ed and honed to the piston. In short, each piston should be a custom fit. Each piston should be numbered to the bore that was honed for the match. All piston rings should have been custom gapped for each bore. All of your engine’s critical parts should be laid out on the workbench in order for error-free assembly.
Take organization to extremes. Number each cylinder with a magic marker at the block deck. Lay pistons and rods out on the bench in cylinder number order. Study the valve reliefs in the pistons. You would be amazed how many engine builds we’ve witnessed where the pistons were installed backwards. Closer attention to detail during assembly could have avoided the inconvenience of disassembly. Valve reliefs always go toward the top of the block with small-block Fords (except 351C).
Keep a can or two of brake cleaner on your workbench to last-minute clean parts during assembly. This eliminates any chance of dust particles and stray matter getting where they don’t belong. Keep plenty of engine oil and assembly lube close by. Keep these items covered.
Unless you are starting with brand new castings and forgings, you’re going to be dealing with disassembly, cleanup, and inspection of parts with your engine build. In any case, you will be dealing with inspection, even with new parts. Just because parts are new doesn’t mean they are right. This is a very critical phase. Overlooking a substandard part can lead to unnecessary engine failure. We have seen new parts that were improperly machined and sized, not machined at all, improperly packaged, and more. Unless parts are washed and closely inspected, it is easy to make a critical mistake and use them when they need to go back in the box. So what to do first?
PROPER ASSEMBLY TECHNIQUE
With proper selection of castings out of the way, we can get into how to properly assemble an engine using tried and proven technique performed by professionals time and time again. We’re not going to show you step by step in this chapter how to assemble an engine. Instead, we’re going to show you methods and practices that work.
When it comes to assembly practices, the pros stress two main areas – cleanliness (hospital clean!) and triplechecking your work. Never assemble an engine in the same area where it is torn down. Even the minute amounts of dirt, dust or grit can stop an engine cold. Ordinary house dust can score bearings and cylinder walls. Keep your work covered when you’re not working. Keep the area clean.
We stress double and triple checking your work because it actually saves you time. If it’s inconvenient to check it two or three times, consider the inconvenience involved in a nuisance tear down because there’s oil consumption or having to pick up the pieces of a scattered engine because a rod bolt was missed during the torquing process. Check it thrice and sleep better. Engine building really is an exact science where every detail must be covered to ensure success. Even with all details covered, it is no guarantee an engine will stay together. It is those troublesome areas we cannot see that can fail when least expected. This means you must be attentive to everything you have control over in the build process.
DEGREEING A CAMSHAFT
We’ve been over this once before in Chapter 2, but we’re going to touch on it again, just in case you missed it. Why degree a camshaft? Because degreeing a camshaft should always be an integral part of an engine building plan. We degree or dial in a camshaft because this process eliminates all doubt about camshaft, crankshaft, and timing set integrity. It tells us valve timing events and cam lobe specs in great detail. And, believe it or not, cam grinders do make mistakes. Camshafts get packaged incorrectly. And camshafts don’t always get ground to the specs on the card. Degreeing in your camshaft is a fact-finding mission.
When we degree a camshaft, we’re determining valve timing events as they relate to crankshaft position. The crankshaft makes two complete revolutions for every one revolution of the camshaft. One full revolution of each is 360 degrees. This means the crank turns 720 degrees and the cam 360 degrees. Think of rotation like a pie. Half a turn is 180 degrees. A quarter of a turn is 90 degrees.
Duration is the number of degrees of rotation the camshaft will make from the time the valve begins to open until the time it closes. When we see 244 degrees of duration, this means 244 degrees of camshaft rotation from valve unseat to valve seat. Overlap or lobe separation is the number of degrees between maximum valve lift intake and maximum valve lift exhaust. With all this in mind, we can degree the camshaft timing events in time with piston travel.
When we advance or retard camshaft timing, we do it in the number of degrees of crankshaft rotation. Out of the box camshafts typically have some degree of valve timing advance programmed in by the manufacturer. When we time a camshaft straight up, this means we’re keeping the cam in the manufacturer’s suggested position on the spec card. Call this point zero or straight up, then advance or retard valve timing from there.
Few things are more frustrating than a new engine that leaves oil spots on your driveway. This is why you must be as painstaking with leak prevention as you are anywhere else in your stroker build-up. Whenever possible, use a late-model 5.0L or 5.8L block with the one-piece rearmain seal. The one-piece seal does an extraordinary job of keeping oil inside the engine. It is also very simple to install.
Your engine’s valvetrain is likely the most tortured collection of moving parts in the engine. At 6000 rpm, valves slam against their seats 3000 times a minute. Exhaust valves not only reciprocate vigorously at half the speed of the crankshaft, they’re subjected to combustion temperatures of approximately 1800 to 2000 degrees F. Lifters, pushrods, rocker arms, and valvesprings take a similar amount of punishment. Of all your engine’s components, valvetrain components are the most likely to fail. Many a broken valve spring or failed keeper has brought down the mightiest of engines. This is why your attention to this area is vital.
A valvetrain’s greatest ally is stability. Valvetrain systems must have matched components for stable operation. This is why camshaft manufacturers have gone more to camshaft kits in recent years to help us choose the right combination of components. Camshaft companies make it easy to package your valvetrain system. Packaging a valvetrain depends on how you want your engine to perform. If you’re building a street engine that will be operating in the 2500 – 5500 rpm range, camshaft specifications need to be conservative on the side of torque. The cam should be conservative because we want the engine to make good low-end torque for the street. As a result, lifters, pushrods, rocker arms, and springs need to follow suit. Run a spring that is too soft for your camshaft and your engine will experience valve float (not enough spring pressure to close the valves in a timely fashion) at high RPM. Likewise, run a spring that’s too stiff and you can wipe the cam lobes from excessive pressure against the lobe. This is why running matched components is so important.
Four basic lifter (tappet) types are used in small-block Fords – flat tappet hydraulic and mechanical, and roller hydraulic and mechanical. Flat tappet lifters were original equipment prior to 1985 when roller tappets debuted inside the 5.0L High Output V-8. Roller tappets found use more and more in Ford factory V-8 engines after 1985. More and more engine builds are witnessing the use of roller tappets because there’s less friction, smoother operation, and the ability to run a more aggressive profile without the drawbacks of a radical flat tappet camshaft.
Roller tappets are more costly than flat tappets due to tighter tolerances and a greater number of parts. Their cost puts them outside of the budget engine category, but they’re worth every penny in what they save in wear and tear. They also give you the advantage if your desire is to run a more aggressive camshaft profile.
Hydraulic lifters saw more widespread use beginning in the 1960s, although their use dates back to the 1920s. Hydraulic lifters don’t require periodic adjustment like a mechanical or solid lifter. As the camshaft and valvetrain wear, hydraulic lifters expand with the wear via oil pressure to take up clearance. This keeps operation quiet and reliability sound. Hydraulic lifters do well until cam lobe and valvestem wear is so excessive the lifter can no longer take up the clearance. Then we hear the tell-tale click or tapping of rocker-arm noise, especially when the engine is cold. Sometimes rocker arm click is a faulty lifter (leaking down hydraulic pressure) or an excessively worn rocker arm. This is especially true with the rail-style rocker arms Ford used from mid 1966 until the 1978 model year. Rail-style rocker-arm tips wear at the valvestem, which eventually leads to the rails digging into the retainer. The first indication of an excessively worn rail rocker arm is that clicking that occurs at any engine temperature.
Lifter and cam lobe wear and failure are rarely caused by a manufacturing defect. They fail because we don’t give them a good start when it’s time to fire the engine in the first place. Flat tappet camshafts must be broken in properly or failure is inevitable. Moly coat must be applied to the cam lobe and lifter face when you’re installing a flat tappet camshaft. The engine must be operated at 2500 rpm for 20-30 minutes after the initial fire-up to properly wear in the lobes. Synthetic engine oil should not be used until after the break-in period. During this period, check the pushrods for rotation.
Roller tappets don’t require breakin because rollers and cam lobes enjoy a good relationship to begin with. The lobes are already hardened and rollers provide a smooth ride. Roller tappets can even be reused with a new camshaft if they’re in good condition. If you’re building a high-mileage engine, we suggest the use of new roller tappets with a new camshaft.
Flat tappet mechanical camshafts are good for high revving engines where the inaccuracies of hydraulic camshafts (lifter collapse) are unacceptable. Mechanical camshafts give us accuracy because there’s nothing left to chance. The lift moves with the cam lobe with solid precision. Given proper valve lash adjustment, mechanical lifters do their job very well. The thing is, mechanical flat and roller tappets have to be adjusted periodically, which can be annoying on a daily driven street engine. This is where you will need to do some soul searching before selecting a camshaft and valvetrain.
ROCKER ARMS & PUSHRODS
The pushrod and rocker arm transfer the cam lobe’s energy to the valvestem. Think of the rocker arm as the camshaft’s messenger, because the rocker arm multiplies lift, which makes the valve open further than the camshaft’s lobe lift. Rocker arm types range from stock cast affairs all the way up to extruded and forged pieces with roller bearings and tips. Forged or extruded roller rocker arms are quite costly, which generally leaves them out of a budget engine program. However, this doesn’t mean you have to settle for stock cast or stamped steel pieces either.
Stock cast or stamped steel rocker arms don’t perform well under the heavy demands of radical camshaft profiles. An aggressive camshaft profile will break a stock rocker arm in short order. This is why it is always best to err on the side of heavy-duty whenever you’re building an engine. Stamped steel, ball-stud, rollertip rocker arms are a good first step toward valvetrain durability whenever you opt for a higher lift camshaft. The roller tip reduces the stress we experience with stock rocker arms. The thing is, when we increase lift and valve spring pressures, a stamped steel or cast roller tip rocker arm doesn’t always stand up to the test, especially when spring pressures climb to over 350 pounds. Even the best stamped-steel, roller-tip rocker arm will fail when overstressed.
When lift and spring pressures go skyward, you’re going to want a roller pivot, roller-tip forged rocker arm for your budget engine build. Going that extra mile with a super durable rocker arm ensure longer engine life, especially if you’re going to drive it daily. For the weekend racer, stepping up to a better rocker arm is like writing a life insurance policy for your engine, because marginal rocker arms will not stand up to the high-revving task. Roller pivot, roller-tip rocker arms also ensure valvetrain precision and accuracy when the revs get high.
We suggest looking to Crane Cams, Comp Cams, or Crower for your Ford engine rocker arms and pushrods. These companies all have a lot of valuable experience with valvetrain components and offer wide selection. Good rule of thumb is to run the same brand of rocker arm and camshaft. See your favorite camshaft company or speed shop for more details.
When it comes to valvetrain adjustment, small-block Fords have flexibility in available aftermarket adjustable studs where adjustable studs were not originally used. The same is true for the 351C/351M/400M middle blocks. Early small-block Fords (1962-1967) had adjustable, ball/stud-mounted rocker arms. From 1968 to 1977, small blocks received no-adjust, positive-stop rockerarm studs that are undesirable for the performance buff. From 1978 to present, the rocker arm stud was replaced with a new-design stamped-steel rocker arm, fulcrum, and bolt that mount atop a boss on the head.
Small-block Fords from May 8, 1966 and up have rail-style rocker arms, which eliminate the pushrod guide that was cast into the cylinder head. The rocker arm’s side rails keep the rocker arm centered on the valvestem. The problem is, as the rocker-arm tip wears at the valvestem, the rails move closer to the valve spring retainer. As the rails push down on the retainer, the risk of valve keeper failure increases. When the keeper fails, the valve drops into the cylinder causing major engine failure. Excessively worn rail-style rocker arms cause a tell-tale clicking during engine operation. Close examination of the valve spring retainer will reveal wear marks from the rails if wear is excessive. Rail-style rocker arms don’t perform well with high-lift camshaft profiles because the rails can contact the retainer. Sometimes these rocker arms pop off to one side or the other at high revs, pressing on the retainer and risking engine failure. During a rebuild, we suggest the use of 1962-1966-style conventional rocker arms with screw-in studs and pushrod guide plates for best results. For engine integrity, there really is no other choice.
The 335-series small-block engine family (351C, 351M, 400M) had two types of rocker arm arrangements from the factory. The Boss 351 (1971) and 351 High Output (1972) had adjustable, stud-mounted rocker arms. The rest had bolt/fulcrum style, no-adjust, stampedsteel rocker arms like we find on smallblock Fords from 1978-up.
Small-block Fords sport an array of rocker-arm combinations depending on generation. We’re going to walk you through how to do valve lash adjustment on each. Small-block Fords from 1962- 1967 have adjustable ball-stud rocker arms. There are different theories on how these should be adjusted. Adjustment depends on how your engine will be used. For street engines, the best approach is to turn the rocker-arm stud nut clockwise (engine warm) until the rocker arm contacts the valvestem, then tighten the nut 1/2 to 3/4-turn.
Ford small blocks from 1968 to 1977 have no-adjust, positive-stop rocker arms, which makes adjustment impossible. However, modifying 1968- up heads with screw-in studs and pushrod guide plates makes adjustment possible. This is strongly suggested with your stroker project.
Beginning in 1978, small-block Fords were fitted with bolt/fulcrum, stamped-steel rocker arms, like the 335- series 351C, 351M, and 400M V-8s we’re about to address. The 335-series engines also have no-adjust, bolt-fulcrum rocker arm set-up with the exception being the Boss 351C, which had mechanical lifters and adjustable ball/stud rocker arms.
When you’re shopping for pushrods, we suggest a lightweight 5/16-inch ,welded-ball tip, chrome-moly piece for the best reliability. Regardless of budget, we must have components that will withstand the torture of valvetrain vibration and oscillation or the situation gets unpleasant quickly. A failed pushrod at high RPM can do extensive engine damage to a point where you will forget all about all that money you were trying to save.
Proper pushrod length is a very serious consideration for any engine builder. As we said earlier, it can mean the difference between long engine life and having to pull heads in a few thousand miles. A pushrod that’s too long will push the rocker-arm tip under-center, causing excessive side loading to the valvestem and guide. Likewise, a pushrod that’s too short will do the same thing on the opposite side. A pushrod checker will help you make the right decision for not much money. You can find one of these at your favorite speed shop and get right to work in your search for the correct length pushrod.
When you’re checking pushrod length, you want the rocker-arm tip to be close to center on the valvestem tip. Remember, the rocker-arm tip is going to walk across the valvestem tip when we come up on the high side of the cam lobe. Take a black felt-tip marker and darken the valvestem tip. Then install the rocker arm and pushrod. Hand crank the engine and watch the valve pass through one full opening and closing. Get down along side the rocker arm and valvespring and watch how the rocker arm travels. Then inspect the black marking for a wear pattern. This will show you exactly where the rockerarm tip has traveled across the valvestem tip. The pattern should be centered on the valvestem tip. If it runs too much toward the outside of the valvestem tip, the pushrod is too short. If it runs toward the inside of the valvestem tip, the pushrod is too long.
VALVES & SPRINGS
Valves and springs play an important role in power and reliability. Weak spots in either area can rob you of power or lead to engine failure. This is why choosing the right valves and springs is so important. Most cam manufacturers offer a variety of valve spring combinations designed to work well with the camshaft you have chosen. In fact, the best way to shop and buy a cam is to purchase a camshaft kit, which includes valvesprings, retainers, and keepers matched to the camshaft profile chosen. We match a cam and springs because we want a compatible spring for the cam profile. More radical cams call for stiffer springs. Milder camshaft grinds need less valvespring pressure. Too much spring pressure can wipe the cam lobes. Too little can cause valve float (valve seating doesn’t keep up with the revs) at high revs.
Choosing the right valvespring is strictly a matter of following a camshaft grinder’s recommendations. Most springs are applicable to hydraulic or mechanical lifters. Some are specific only to roller camshafts. Crane Cams, for example, offers dozens of different valvespring types. The part number you select depends on camshaft profile. See your cam grinder for more details.
When you opt for a camshaft kit, there’s comfort in knowing the manufacturer has matched the springs to the camshaft profile. Most of the homework has been done for you. There won’t be concern about coil binding, or too much or too little spring pressure. The best time to check for coil bind is when you’re degreeing in the camshaft. Do this before permanently bolting on the heads. Most cam grinders will tell you the recommended installed spring height and seat pressure. Correct installed height and spring pressure are achieved with the use of shims as necessary. Coil bind is checked by checking coil spacing with the valve at maximum lift. There should be no less than .040-inch between the coils at full valve lift. Retainer to valve guide clearance at full lift is the same – no less than .040-inch. This clearance is vital because coil bind or retainer contact with the head will cause valvetrain failure. The .040-inch we give it allows for thermal expansion of metal parts and any camshaft aggressiveness at high revs.
Another huge consideration whenever you’re installing a camshaft with greater lift and duration is piston-tovalve clearance. The most common practice is to press modeling clay into the piston valve reliefs, temporarily install the head and valvetrain, then turn the crank two full revolutions. If you feel any resistance, back off and remove the head. Chances are you have piston-tovalve contact. Forcing the crank will bend the valve and/or damage the piston. If no resistance is felt in two turns of the crankshaft, remove the head and examine the clay. Slice the clay at the valve relief and check the thickness of the clay. This is your piston to valve clearance.
And finally, whenever you’re rebuilding cylinder heads, always remember the valve guides and valve to guide clearances. Loose valve to guide clearance leads to loss of oil control. Clearances that are too tight can cause the valve to seize to the guide when the engine is hot. Precise valve-to-guide clearance and healthy seals make every difference.
STROKER TUNING & OPERATION
What we do with a stroker small block after assembly is complete is just as critical as the actual build-up. Improper performance tuning can damage an engine just as easily as dust and grit on bearing surfaces. Tuning begins with cylinder head, camshaft and induction selection, which determines how you will tune the engine in operating form. We presume you have already chosen the right camshaft, cylinder heads and induction system for your engine. This subject is covered earlier in Chapter 2. This leads us to what to do once the engine is safely nestled in your engine bay.
Before the engine is fired for the first time, it needs to be ready for a safe start-up. Fill the oil pan with the appro priate amount of SAE 30 weight engine oil. If you’re going to use a synthetic engine oil, like Mobil 1 or Royal Purple, wait until the engine has 500 to 1,000 miles before switching over. Personally, we suggest the use of Castrol SAE 30 or 10w30 weight oil for your initial fire-up and break-in.
With the oil pan supplied and a Mobil 1 filter installed, the oiling system needs to be primed. When we prime the oiling system, we run the engine’s oil pump to supply the bearings and cylinder walls with plenty of lubricating oil. This ensures that all lubricated surfaces have plenty of oil for the first fire-up. Oil system priming should happen within one hour of engine start.
We prime the engine’s oiling system with a oil pump primer, which fits into the block in place of the distributor. The oil pump primer is propelled by an electric drill capable of turning the pump drive. Oil system priming should be done with the valve covers removed to check oil flow from the pushrods and rocker arms. Although it is physically impossible to check bearings for oil flow, oil flow at the rocker arms is a good indication that oil is flowing everywhere. Oil system priming is good not only for lubricated surfaces, but to fill the hydraulic lifters with oil prior to fire-up.
With oil pump priming out of the way, it is time to static tune the engine for fire-up. Crank the engine slowly, putting the #1 piston at top dead center on compression stroke (both valves closed). Installing a distributor in a small-block Ford can be very frustrating because the distributor doesn’t always mate smoothly with the oil pump shaft. Slip the distributor into place, locating the rotor at #1 on the distributor cap. If the distributor does not seat, have someone jab the starter quickly, which will turn the camshaft and distributor, allow the distributor to find a smooth marriage with the oil pump shaft. Once the distributor is seated, crank the engine and determine correct location of the rotor. With the #1 cylinder at TDC on compression stroke, the distributor rotor should be at #1.
With static ignition timing out of the way, it is time to double check valve clearances. If you are running a hydraulic camshaft with adjustable rocker arms, crank the engine and follow the firing order to check valve adjustment. Most hydraulic roller camshafts have a 351W firing order, even if they’re installed in a pre 1982 289/302ci engine. Determine your camshaft’s firing order before getting started.
Begin with the #1 cylinder, with both valves closed. Loosen the rocker arm nut until the rocker feels loose. Slowly tighten the rocker arm nut until the rocker touches the valvestem. Tighten 1/2 to 3/4-turn. Move on to the next valve duo in the firing order, handcranking the engine until both valves are closed at compression stroke.
With the oiling system primed, the distributor installed and properly timed, and all 16 valves properly adjusted, it is time to set up the fuel system for a safe start. We’re going to address the many types of carburetors in order to get you started on the right foot. Our objective is to get the air/fuel mixture adjusted in the middle of the road, and the idlespeed screw set where it should be for a slightly fast idle (around 1,000 rpm).
Because firing an engine for the first time can be nerve racking, we want to take the safest approach possible. Engines fitted with roller-tappet camshafts don’t need the faster break-in speeds needed for flat-tappet camshafts. If you’re running a roller-tappet camshaft, run the engine at 1,000 to 1,200 rpm for a good warm-up and piston ring seating.
When an engine is fitted with a flat tappet camshaft of any kind, we need to start the engine and allow it to run for 20-30 minutes at 2,500 rpm for proper camshaft lobe break-in. This allows the cam lobes to wear in and achieve a hardened surface. This is a process you don’t want to fail with. If you skip this step, you can expect to wipe the cam lobes in short order. Then, you get to replace the new camshaft.
BEFORE YOU SPIN IT
Before firing an engine, check two very important things – coolant and oil levels. Fill the radiator with straight water for that first firing, just in case there is a leak. We suggest running a coolant filter in the upper radiator hose to catch any iron or machining particles that would block new radiator tubes. Small-block Fords are notorious for stray iron particles that clog new radiators and heater cores.
Note that we said “new” radiator tubes. Never put a new engine into service using an aging and dirty radiator. We see this sort of thing all the time. Performance enthusiasts, suffering from the sticker shock of an expensive engine build, just don’t have the heart, or the money, to purchase a new radiator. But if you’re going to build an engine, dial the cost of a good support system into the budget. That support system should include a radiator that is clean, serviceable, and ready to extract heat from a fresh engine. Fresh engines tend to run hot because break-in involves a certain amount of friction at the cylinder walls, bearings and journals, and valvestems.
When you’re shopping for a radiator, always opt for a lot of cooling capacity. Classic Mustangs and other vintage Fords need four-row core radiators for maximum cooling effectiveness. And despite what you’ve heard about aluminum radiators, the old-fashioned tried and proven copper and brass radiator offer better cooling efficiency than aluminum. The only real disadvantage to copper and brass radiators is weight. They’re heavier than aluminum radiators. Using a fan shroud around the cooling fan helps keep air velocity through the fins and tubes where it belongs. And one more thing about that fan-shroud. The fan blade tips should be half-exposed around the perimeter of the shroud. If the fan shroud completely covers the fan blade tips, you will lose cooling effectiveness. In fact, your engine will run considerable hotter with the fan blade tips covered. The reason we want the fan blade tips half exposed is airflow. Airflow needs to travel through and past the blade tips, which pulls more air through the radiator. When we completely shroud the fan, we greatly limit airflow through the fan.
The most efficient type of cooling fan, besides the electric fan, is an enginedriven thermostatic clutch fan. Thermostatic clutch fans free-wheel when they’re not needed, engaging and turning with the water pump as needed. On a cool day, clutch fans do very little work. When it is hot, the clutch engages, moving critical air through the radiator. Fill your radiator until the water level is 1-inch below the neck. Leave the cap off. In order to bleed any and all air bubbles out of the water jackets, remove the heater hose at the intake manifold and wait for water to rise to the nipple. This ensures most air has been displaced with water inside the block and heads. Fresh engines, especially, don’t need hot spots in the block and heads, which can cause significant damage and ruin proper break-in.
With the engine at operating temperature, it is time for initial tuning. For initial tuning, you will need an intake manifold vacuum gauge and a timing light if you’re working with a carbureted engine. For fuel-injected engines, you need a scan device to check for fault codes. Ideally, you will have an exhaust gas analyzer to examine mixture in either case.
Ignition timing should be checked first. Rev the engine to 3,500 rpm and hold it there, checking ignition timing with a timing light. This is where total spark advance should come into play. Depending on the camshaft you have chosen, total spark advance at 3,500 rpm should be 39-41 degrees BTDC (before top dead center). This allows your engine to take advantage of the air/fuel charge. Ignition timing at idle speed (roughly 600-800 rpm) should be around 12 degrees BTDC. Because vacuum advance units all must be calibrated for each specific application, you may have to make adjustments.
Aftermarket vacuum advance units are calibrated with an Allen wrench through the vacuum port. Turn the Allen wrench clockwise to slow the rate of spark advance. Turn it counter clockwise to increase the rate of spark advance. Slowing the rate of spark advance means the spark advance won’t go to full advance as quickly. Speeding up the rate of advance means you will get full advance before the engine reaches 3,500 rpm. When this happens, you will likely hear detonation (pinging or spark knock) under acceleration. Pinging or spark knock is a bad thing. It means detonation is hammering the piston pin and rod bearings at the least. Worst case scenario, you will burn pistons. If there isn’t enough spark advance, your engine will nose over and fall on its face. You won’t get the power desired without enough spark advance.
With the engine at operating temperature and the ignition timing where it belongs, you’re ready to adjust the fuel mixture and idle speed. Ideally, you will have adjusted your ignition timing at both normal idle speed and at 3,500 rpm. This leaves only the fuel/air mixture to check. In any case, hook up the vacuum gauge below the carburetor base plate where there is a constant vacuum and examine the vacuum reading. A normal,healthy idle should show 18-22 inches of vacuum. Of course, the more radical the camshaft, the lower the vacuum reading will be. With a streetable camshaft, vacuum should be healthy. Turn each mixture screw in one at a time until the idle begins to falter. Vacuum should falter as well. Slowly back the mixture screw out until the idle stabilizes. Seek the highest vacuum reading possible while adjusting the mixture screws. Do the same on the other side. Listen to the engine’s idle. Is it smooth? What is your vacuum reading?
With all basic tuning out of the way, observe the way the engine idles. Listen to the valvetrain for noise. Lay under the vehicle and listen to the bottom end for unusual noises. Examine the oil pressure. Oil pressure should be 10 psi for every 1,000 rpm. This means your engine should be holding a solid 10-20 psi of oil pressure at idle speed. At 4,000 rpm, you should have at least 40 psi of oil pressure. If you’re dealing with a fuel-injected small block, it would be a good idea to check fuel pressure, which should be at least 40-45 psi. If it is low, suspect either the fuel pressure regulator or the electric fuel pump. Low fuel pressure can cause engine damage under hard acceleration and/or during the use of nitrous. Make sure your SEFI (sequential electronic fuel injection) small block is getting adequate fuel pressure.
After 500 to 1,000 miles of driving, do a spark plug reading on all eight cylinders. Your engine’s spark plugs should have a light tan color with a minimum of deposits. If they are snow white, the mixture is too lean. If they are a sooty black, the mixture is too rich.
Stand at the tail pipes and listen to the engine at idle. Place your hand at the tailpipe and feel the pulsing. Is it consistent? Or is there a misfire? If there is any hint of suction at the pipe, this indicates exhaust valves that may not be seating properly. The exhaust pulse should be smooth and consistent. Have someone rev the engine and hold it at 3,000 rpm. Listen to the exhaust pulse. Again, it should be consistent. Any misfire or uneven pulsing is an indication of irregular fuel mixture or ignition timing that is too advanced. When the timing is too far away, an irregular misfire will occur. Back the timing off in slow increments until the misfire fades to a smooth pulsing at the tailpipe.
If all of this seems like a bit much, consider how important proper tuning will make a difference in longer, more reliable engine life. Good tuning not only makes a difference in engine life, it makes a big difference in performance. This is the time to give your engine the good start it deserves.
PREVENTIVE STROKER MAINTENANCE
How do you keep a good healthy stroker small block alive? Most of it depends on you, your driving technique, and how often you take care of underhood maintenance. Throughout a lifetime of experience and significant changes in the world of internal combustion engines, we have learned there is no better life insurance policy for an engine than regular, preventative maintenance. Oil and filter should be changed every 3,000 miles. Once an engine has passed the 1,000-mile mark, we highly recommend the use of a quality synthetic engine oil like Mobil 1 in 10w30 weight. Of all of the filters we have used through the years, the two best ones are Mobil 1 and Purolator. If it boiled down to choosing between the two, we would choose Mobil 1. Mobil 1 oil filters employ an abundance of filtering material, making them a superior filter. The Mobil 1 oil and filter combination is unbeatable for safe engine lubrication.
Once you have confirmed the cooling system to be leak-free, completely drain the cooling system of all water. Remove the block drain plugs to ensure all coolant has escaped. Purge the heater core of all coolant.
When the cooling system is completely drained, fill it with a 50/50 mix of antifreeze and distilled water. Do not use tap water. Tap water often contains minerals and other contaminates that can be harmful to the engine’s water jackets and radiator from a corrosion standpoint. The more pure you can keep your engine’s coolant, the longer the cooling system will last.
Another option for performance buffs is Evans NPG+ non-aqueous propylene glycol coolant. This is a dream-come-true coolant designed to make dramatic improvements in heat transfer and viscosity. You can literally pour this no-water coolant into your radiator without any concern for coolant mix. This is because NPG+ is all the coolant your engine will need. All water must be purged from the cooling system when you use NPG+.
NPG+ pulls heat from your engine better than conventional antifreezewater mixes. Whenever you run the antifreeze/water mix, boil-over can occur around 225 degrees F. sWith a closed radiator cap, the boiling point is raised to 259 degrees F, depending on where you are. NPG+ offers you even greater temperature limits because it doesn’t boil until 375 degrees F, not that we would recommend running your engine at this temperature. NPG+ is a lifetime coolant that never has to be replaced (unless contaminated).
Written by George Reid and Posted with Permission of CarTechBooks