You need to have clear performance goals, a detailed list of proposed machine work, and a definite budget when you arrive at the machine shop with your Modular engine. This way, you are able to answer all the machinist’s questions.
This Tech Tip is From the Full Book, 4.6L & 5.4L FORD ENGINES: HOW TO REBUILD. For a comprehensive guide on this entire subject you can visit this link:
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First, you need to have all castings and components thoroughly cleaned and inspected before investing in expensive machine work. A machine shop usually performs this procedure, but it costs you whether or not you use the castings. Once these parts are completely cleaned, inspected, and approved for machine work, it’s time to start. I inspect all parts for cracks, warping, and other irregularities. There’s no point in performing machine work on any part that is ultimately discarded.
Your machine shop must approach Ford’s Modular V-8 differently than any other Ford engine. Each machining step must be performed with great caution and precision because tolerances are extremely tight. This means your Modular V-8 is a precision machine, unforgiving of carelessness and sloppy machine work. The boring and honing process, for example, calls for close attention to detail, meaning cylinders in thin-wall castings become warm and expand as they are bored and honed. Honing is a painstaking incremental process.
Cylinders need to be checked with a dial-bore gauge with every couple of passes of the hone and allowed to cool before honing continues. Therefore, the machinist must exercise patience and precision, and, of course, this increases the cost of machine work. But the savvy machinist hones, checks with the dial-bore gauge, checks again, then allows bores to cool before checking yet again. And this tedious yet necessary process makes the Modular engine building experience different from that of many other engines.
If your machinist is unwilling to go this extra mile, find one who is, because it’s costly to have to do anything a second time. In fact, careless machine work can cost you a block or a head casting, and once the damage is done, the parts are throwaways.
So what is all this machine work about and why is it necessary? First, you have to understand the difference between an engine “overhaul” and a “rebuild.” Often, an engine overhaul is little more than a ring, bearing, and valve job, which costs less and simply freshens the engine. It’s a Band-Aid fix, and it only buys you time.
When you perform an engine overhaul, you knock your engine down to the bare block, cut the ridges at the tops of the cylinders (in order to remove the pistons and rods), run a ball hone up and down the cylinders to cut the glaze, inspect the bearings, and replace what needs to be replaced. An overhaul tightens things back up for a while, but it isn’t really a permanent fix. Under the worst of circumstances, overhauls take place in the vehicle.
An engine rebuild molds new life into a worn-out engine. If performed properly, and with great attention to detail, an engine rebuild can mean 100,000 to 300,000 miles of new life with proper maintenance and care. The engine gets a new lease on life from complete machining and the installation of quality parts.
Be Environmentally Responsible
How does your machine shop clean engine parts? Does it use an old lye tank? Does it use modern methods that don’t work and you wind up with a clean, yet rusty casting? When you’re shopping for a machine shop, you want the best of everything. You want a machine shop that is technically proficient. And, you want a machine shop that uses the best cleaning technology available.
Begin the block machining process with a thorough cleaning. In the good old days, you used to dunk the nasty castings in a lye tank to clean them. In the interest of a cleaner environment, machine shops now use new, more responsible cleaning processes. JGM Performance Engineering, which is building the engine for this book, uses the latest cleaning technology.
JGM begins by cooking dirty, grimy castings at high temperature. Once that process has been completed, castings are placed on a rotisserie where they are blasted with steel shot. Next, the casting is treated to a tumbling process in which all-steel shot is shaken and blown out. When iron and aluminum castings emerge from the cleaning equipment, they look like new. This is something that an old lye tank could not accomplish even on its best day. Not only do you have cleaner castings, you have a cleaner environment.
With a clean block, check all water jackets and oil passages for cleanliness. Even though your block may look hospital clean, you are bound to miss some areas if you don’t pay close attention. Oil passages and water jackets need a thorough pass with solvent and a wire rat-tail brush. In fact, you need to do this again and again until you are positive all debris has been removed because any debris can cause serious engine damage. All freeze plugs and oil galley plugs must be removed for this process.
Before you even consider boring the block, you need to check each cylinder bore for taper and other irregularities. I suggest this because some blocks are bored that don’t need to be bored. This is wasteful. If cylinder bore taper is less than .011 inch from top to bottom, you can get away with honing to the next oversize of .005 inch with a fresh set of oversize pistons and oversize rings.
Most blocks should be bored to .020- inch oversize. If you have .020-inch oversize pistons, opt for this size rather than the more traditional .030-inch overbore. This buys the block at least one more rebuild.
While checking the bore taper, also check the line bore. You need to check line bore of the main bearing saddles and caps for proper alignment and dimension. Most of the time you can get away with honing the line bore. You hone the line bore just as you hone cylinders or recondition connecting rods. This means scoring the main bearing contact surfaces to improve bearing adhesion and crush with main caps. The objective is to provide proper main bearing-to-journal clearances while preventing them from turning in the saddles. That’s why you want not only proper sizing, but also a good crosshatch pattern for positive bearing retention.
A good machinist considers every angle when it comes to main bearing saddles. According to JGM Performance Engineering, you should remove main bearing caps and resize them. You do this by milling each cap, countersinking the bolt holes, and resizing each cap. When you mill main caps, it throws the main saddles off center. This makes it necessary to hone and resize the main saddles. With the main bearing saddles (line bore) resized, you have a perfect line bore. If your budget is limited, resizing the line bore isn’t necessary.
Step 1: Main Saddle/Line Bore Preparation
The main bearing saddles are ready for dressing and honing. Closely inspect everything to be sure the surfaces are clean and the oil galleys are unrestricted. Perfectly align main bearing saddles to prevent abnormal crankshaft and main bearing wear. (This step is known as checking the line bore.) Dress main cap contact surfaces with a file to remove any high spots. Chase and bathe bolt holes in engine oil. Always ensure bolt holes are clean and clear (this includes engine oil) when it’s time to install main caps. Fluid in the bolt holes can “hydro-lock” when bolts/studs are tightened, which can crack the block and damage threads.
Step 2: Use Main Studs Instead of Bolts
Modular engines use torque-to-yield (torque-angle) hardware, so I’ve tossed the factory main cap bolts in favor of new ARP studs, which provide more security. All blocks need to be thoroughly cleaned. Chase every bolt hole and lubricate stud threads with engine oil. Studs need to be run down by hand just short of bottoming out, but not tightened. You must use the same bolts/studs in the main caps for line honing that will be used in the engine when it’s assembled because Modular engines have finite tolerances and are unforgiving of error. If you use main bolts for line honing and then main studs for main cap installation later, main cap positioning is different, and therefore, the line bore is irregular. Always use the same fasteners for line honing and final assembly. Always use new fasteners.
Step 3: Check Line Bore
Use a dial-bore gauge to check the line bore. Check main bearing saddle diameter and write it down for a reference point before machining begins. Main journal bore dimensions should be 2.850 to 2.851 inches (72.401 to 72.422 mm). Record all data for reference later.
Step 4: Machine Main Caps
As with any engine rebuild, you machine the main caps so they are square with the block. When this happens, you made the main saddle bore too small. This is why you line hone back to the correct size. This is how you get the line bore perfectly square for smooth crankshaft rotation. Take off just enough metal to square the main caps before you begin line honing.
Step 5: Dress Main Caps, Remove Stress Risers (Professional Mechanic Tip)
After machining, dress the main caps to remove stress risers and sharp edges. This minimizes the chance of cracks and material failure and makes installation easier. Sharp edges create stress points where cracks can begin. A stress riser (rough edge) is like a chisel tip. Put a chisel against metal and tap on it with a hammer. With enough force and time, you’re going to break the metal. Stress risers have the same effect.
However, if you want to make an engine like new in every respect, resizing the line bore is very important and well worth the investment. You do this because the factory doesn’t always make the line bore as true as it should be. JGM gets the bore spot-on with detailed machine work and triple checking its outcome.
Rarely does the line bore need to be bored and honed. Most blocks have a pretty straight line bore from the factory that stays that way for the life of the block. The line bore is critical because this is where the crankshaft lives. A line bore that is out of true causes abnormal bearing wear along with the potential for premature failure. This is why you want the line bore nice and straight.
How does an abnormal line bore cause abnormal bearing wear? By causing pressure points along bearing and journal surfaces that are supposed to be protected by the oil wedge. You want nice, even contact across all main and rod bearings. Remember, your crankshaft rides on a cushion of pressurized oil that prevents direct bearing and journal contact. Uneven bearing-to-journal contact creates pressure points that inhibit that all-important oil wedge, which keeps journals and bearings from contacting each other. Lose that oil wedge, and you will experience engine failure. Metal-tometal contact leads to spun bearings, oil starvation, and engine failure. This is why line bore, a cross-hatch pattern, and bearing security are so important.
Once line bore is within spec, the block is bored to the next oversize. I strongly recommend oversizing in small steps. Measure the bores and determine how much you need to remove. See if you can get away with .010-inch oversize, which requires only honing. Most of the time you can get away with .020-inch oversize. Reputable machine shops bore blocks in stages, usually .005 inch at a time. With a .020-inch overbore, each cylinder is ultimately bored .015 inch,then honed the rest of the way (.005 inch) to match the piston size. You’re actually going to dial-in .002- to .004- inch piston-to-cylinder wall clearance. Not all pistons measure exactly 3.550 inches or 3.570 inches. Each piston is measured to each bore. Piston-tocylinder wall clearances can vary from bore to bore; hence, there is the need for match boring and honing. This is why you measure each piston, and then bore and hone each cylinder for a perfect fit. However, not all machine shops matchbore cylinders to fit the pistons because it is time consuming. When this service is performed, it takes more shop time and you pay for it. Some machine shops check one bore and assume the rest are identical, but that’s a poor practice because all bores need to be checked. Ask your machine shop about how it bores and hones blocks. Even if you have to spend more, insist on match honing. It’s worth the investment.
Step 6: Test Fit, Install Main Caps (Professional Mechanic Tip)
Seat each main cap and closely inspect them for proper installation. All contact surfaces must be free of debris. Even a small fragment between the main cap and the block causes irregular main bearing cap seating and, as a result, irregular machining. And that leads to main bearing and journal damage and engine failure. The goal is for the crankshaft to ride squarely on the main bearings to achieve uniform wear and consistent oil pressure.
Step 7: Torque Main Caps For Line Honing (Torque Fasteners)
Torque-to-yield the main caps during line honing according to the spec in the Ford Service Manual. Torque main caps to 22 to 25 ft-lbs, and then 85 to 95 degrees per a torqueto-yield gauge if you’re using new Ford main cap bolts. This sets the main caps for line honing. Because you are using ARP main studs, you need to use a different approach for torquing main caps for line honing. Screw in the main studs just short of bottoming out, using engine oil as a thread lubricant. Lubricate studs and nuts with engine oil. Nuts should be torqued in thirds to 85 to 90 ft-lbs beginning at the number-3 main cap and working outward.
Step 8: Set Main Cap Cross Bolts
Once the main caps are secure, install the cross bolts. Torque the jackscrews (Romeo engines only) to 5 to 7 ft-lbs to load the block. This calls for an Allen wrench. Jackscrews are turned clockwise, which backs the jackscrew out, to load the block (and counterclockwise to loosen).
Cross bolts secure jackscrews and main caps. Torque them to 14 to 17 ft-lbs using a breakaway torque wrench. Jackscrews load the main cap and block skirt to ensure main cap security. Cross bolts screw into the jackscrews to provide a firm marriage between main caps and block skirts. Windsor blocks use dowels and cross bolts instead of jackscrews.
Step 9: Line Hone Block
Carefully hone the main bearing bores with three or four passes, and then check them with a dial-bore gauge. This is very tedious, but necessary because it “right sizes” the main journals, providing a crosshatch pattern that ensures main bearing security. A good pinch fit (also called an interference fit) gives just the right amount of bearing crush. A crosshatch pattern provides solid contact in addition to good crush. Never reuse main bearings. Once the main and rod bearings have been tightened, they lose proper crush and don’t remain secured.
Step 10: Measure Line Bore
Once you’re satisfied with the main bore measurements, check the crankshaft main journals to prepare for main bearing installation and measurement. This calls for removal of all main caps, installation of main bearings, and complete installation of main caps before measuring can begin. This is why Modular engine machine work is more expensive than for a small-block or a big-block Ford. Check tolerances at every phase to verify accurate machining dimensions. Main bearing journal dimensions should be 2.850 to 2.851 inches (72.401 to 72.422 mm) with the journals cold. Remember, journals become warm (and expand) during machining, which alters journal sizing, which is why journals are best measured cold.
Tight piston-to-cylinder wall clearances zap horsepower because the engine runs too hot from internal friction. It’s an easy mistake to make because not all machinists consider the consequences of piston growth and the dynamics of each piston type. All pistons grow with engine heat, and they grow at different rates, depending on the material. Forged pistons expand more than cast and hypereutectic pistons, and therefore, cast and hypereutectic piston clearances are tighter than forged piston clearances. Of course, this needs to be considered when boring and honing the cylinder bores.
JGM Performance Engineering matchhones each bore to the piston for the best results. One bore at a time, JGM hones, checks, hones again, and re-checks. The Modular block is sensitive to heat dynamics, and JGM hones a little at a time to keep heat under control, which ensures cylinder trueness in every respect. And once the job is done, JGM checks bore dimensions after cooldown just to be sure the bore sizing is on the money.
The next phase of machine work is decking the block. Block decks are subjected to the greatest heat and pressures and tend to warp as a result. Most of the time warping isn’t that significant, which means you can theoretically get away with not having to mill the decks. A machinist needs to check each deck with a straightedge to determine deck integrity. A good rule is to “shave” the decks, removing just enough iron so the surface is straight. It’s a good idea to make a .005- inch cut to see what the deck looks like.
Thread chasing is another important step that is overlooked all too often. Thread chasing is simply cleaning all of the threads in the block, including cylinder head bolt threads, main bearing bolt threads, you name it; chase them all. With clean threads and adequate lubrication, you have an accurate torque reading when it’s time to screw an engine together. Dirty, rusty threads on both bolts and blocks cause bolt threads to bind, leading to inaccurate torque readings and potential engine failure.
A can of WD-40 and a thread chaser clean things up nicely. Before you go any further, I suggest screwing a test bolt into each hole to determine smoothness. Once threads are chased, a bolt should glide right through the threads without resistance. And when it’s time to torque these bolts, the readings should be accurate, and you should feel confident.
Step 11: Measure and Match Pistons (Precision Measurement)
Each Speed-Pro hypereutectic piston from Summit Racing Equipment is measured prior to boring and honing. These are Teflon-coated hypereutectic units dished for stock 42- to 50-cc chambers. Each measures 3.572 inches, which calls for additional honing to achieve a perfect match. If you’re doing this by the book, pistons will not only be weight-matched, but bore-matched so each cylinder bore is honed exactly to piston size. Piston-to-cylinder wall clearance should be .012 to .026 inch (.0005 to .001 mm), and it needs to be checked when bores are cool. In addition, piston-to-cylinder wall clearance depends on piston type. Hypereutectic pistons permit tighter clearances than forged versions because forged pistons expand more with heat
Step 12: Bore the Block
Bore the block to .015- inch oversize. Allow each bore to cool before moving on to the next. You want bores to cool before measuring because heat affects size. A warm bore measures larger than a cool bore due to expansion. Make cuts in .005-inch increments, first boring and then fine-finish honing. This is the deep rough cut that comes first, .005 inch at a time.
Step 13: Bevel Cylinder Edges Smooth (Important!)
Bevel each bore on top for a smooth transition of pistons during assembly and honing. When you don’t do this, you risk piston and ring damage from rough edges during installation.
Step 14: Bevel Bolt Holes and Water Passages (Important!)
Bevel all passages and bolt holes for smooth transition and reduced fluid turbulence in water jackets. Do this with all passages.
Step 15: Remove All Debris
Use compressed air and proper eye/face protection to rid the block of all debris. Metal debris from boring can get between the hone and cylinder wall, causing unnecessary damage. Remember: hospital clean.
Oil Galleys and Water Jackets
When Ford assembled these engines, it used press-in oil galley plugs at the front and rear of the block. Most engine builders use this type of oil galley plugs rather than screw-ins, but screw-in plugs don’t take much time to install and can save your engine’s life. JGM taps oil galley holes and fits them with screw-in plugs.
All oil galleys and water jackets need to be cleaned thoroughly to remove debris and rust. Machine work also creates debris that must be removed. Therefore, with all oil galley plugs removed, oil galleys must be flushed and chased with a rat-tail brush, soap and water, and mineral spirits. This removes any unwanted debris that can harm a fresh engine. Clean the block as many times as necessary to achieve hospital-clean galleys because all it takes is one grain of stray iron or steel to score journals and bearings.
Step 16: Torque-to-Yield with Torque Plates (Torque Fasteners)
Always torque-to-yield when you install torque plates, just as you do when installing cylinder heads. Torque bolts from the center out to 18 to 25 ft-lbs, and then 85 to 95 degrees for yield. This simulates cylinder head installation to achieve proper cylinder dimensions. Use a torque plate so the block has the same tension as it would have with cylinder heads installed. A Modular block is better than older Ford V-8s because the cylinder head bolts/studs thread into the block. In fact, they thread deeply into the block near the crankshaft, so there is less distortion when they are tightened. Always lubricate bolt/stud threads with engine oil, but do not use too much (just a light dressing of oil on the threads).
Step 17: Use Torque-Angle Gauge (Torque Fasteners)
A torque-to-yield (torque-angle) gauge tells you the number of degrees you have torqued each head bolt after initial torque is achieved. In this case, it is 85 to 95 degrees tighter after that initial 18 to 25 ft-lbs. Always use a torque-to-yield gauge. If you simply guess, you risk an improper torque angle, and incorrect bolt/stud stretch/tension.
Step 18: Hone Block
Honing begins with coarse stones and a lot of machine oil for lubrication. Because Modular engines have a thin wall casting, make light passes and then check each bore with a dial-bore gauge. This takes longer, but it is worth it. You want cylinder bores to be as true as possible. Hone the bores a total of .005 inch. Fine-tuning comes from custom matching each piston to each bore because no two pistons are the same size. If you take a random approach to honing, you wind up with loose pistons, or worse, tight pistons that could seize when you fire the engine. You want optimum clearance of .0012 to .0026 inch. And remember, clearances need to be liberal with forged pistons.
Step 19: Allow Cylinder Cool-Down Time (Important!)
After the cylinders cool down, check each bore with a dial-bore gauge. Match hone each bore for a perfect piston match. Cool-down is important because cylinders increase in size when warmed from honing, which gives you an erroneous measurement. If cylinder bores are too cool and contract, the dimensions are too tight.
Step 20: Fine-Finish Hone for Best Results
The bore on the left has been finish honed to a nice crosshatch pattern. The bore on the right hasn’t been honed yet and remains rough cut. The finer you can get the crosshatch pattern, the better oil control you have. The same rules apply to finefinish honing. Allow bores time to cool before measuring and take extra care when removing the stone to avoid cylinder scoring. Vertical scoring can cause oil-control issues.
When all machine work is complete at JGM, blocks are washed thoroughly in what looks like an industrial dishwasher. Hot, steamy water blasts the block, removing any stray dirt and debris. During washing, the machine is stopped for a quick chasing of oil galleys and water jackets. The result is a clean block ready for assembly. The cylinder walks and bearing contact surfaces are sprayed with WD-40 to displace moisture and prevent corrosion. Then, the block is mounted on an engine stand and sealed in a plastic bag.
Bottom-end components (crankshaft, connecting rods, and pistons) turn thermal energy into rotary motion and power when you turn the key. These components need your machinist’s closest attention during the machining process.
Crankshafts don’t always have to be machined during a rebuild. Sometimes, you can get away with micropolishing the journals and installing standard main and rod bearings. Each journal needs to be measured with a micrometer. If your 4.6L SOHC is a low-mileage engine, and the crankshaft is flawless, all it needs is micropolishing.
When journals are scored or worn, they need to be machined at least .010- inch undersize. If the scoring is any deeper than .030 inch, I suggest crankshaft replacement. You can get away with a .030-inch undergrind on a mildmannered street engine. Some say that for every .010 inch you grind off the journals, the weaker the crankshaft becomes, although that is open to debate. Most crankshafts are engineered to tolerate even greater undersizes without failure. Going .010- and .020-inch undersize is normal.
While you’re focused on the crankshaft, remember that oil holes need to be chamfered to allow improved oil flow to the bearings and journals. When you chamfer the oil holes, you open up the oil passage, increasing volume. Any reputable machinist and engine builder understands how to do this. It is an affordable and important step in an engine build.
You should also radius the connecting rod journals, which reduces stress and gives the bearing more surface area to lean on. This is common with aftermarket stroker kits. When you radius the journals, you are giving the bearing and the crankshaft a smoother marriage with big shoulders. Ask your machine shop about this step.
Unless you are going racing, shotpeening and nitriding the crankshaft (also known as toughriding) are unnecessary. If your engine will be used for that level of extreme high performance, opt for a steel crankshaft.
As I’ve discussed, most Modular V-8s have cracked-cap powdered-metal connecting rods. Although the single rod forging is precision “cracked” into two pieces (rod and cap), no two rods are cracked the same way, so the rod and cap are married for life. And truthfully, this is the way connecting rods have always been. If you have a bad cap you must throw away the rod.
As a general rule, you should replace powdered-metal connecting rods with new powdered-metal or aftermarket sportsmanstyle I-beam rods during a rebuild. Through the years, the Modular V-8’s weakest link has been the connecting rods. Yet connecting rods haven’t really been a problem in this rugged engine in street applications. Even the screaming, high-RPM, 32-valve Cobra engines have powdered-metal rods in most applications. This means your SOHC street engine is fine with powderedmetal rods, but if you want that added measure of caution, go with aftermarket I-beam performance rods.
Most engine builders tell you that powdered-metal rods should not be reconditioned. However, JGM Performance Engineering reconditions powdered-metal connecting rods all the time, and without a single failure in the many years it has been working on Modular engines. Owner Jim Grubbs says powdered-metal rod reconditioning requires precise machine work and new bolts, which at press time, are not available from ARP. They’re only available from Ford.
Step 21: Remove Pistons, Mark Connecting Rods
Expect to find press-fit piston pins in most SOHC Modular engines. Remove all eight pistons and prepare the rods for reconditioning. Press out the pins with a hydraulic press, taking care not to distort the connecting rod. Check connecting rods for trueness. Maximum bore-tobore twist and bend dimensions can be found in your Ford Workshop Manual.
Step 22: Disassemble Connecting Rods (Important!)
Disassemble all eight rods for close inspection and machine work. Make sure rods and caps stay together by numbering them. Rod bolts must be replaced.
Connecting Rod Inspection (Critical Inspection)
With conventional forged connecting rods, there is a clean parting line between rod and cap. With cracked construction, you rarely have a straight parting line because this is a single piece of metal that has been “cracked” with a sharp blow. Each rod is unique. Caps cannot be interchanged without serious consequences. Try one cap on a different rod and you won’t have proper fit. Accidentally turn it around and you won’t have proper fit either. Cracked rods and caps go together properly just one way.
Step 23: Chase Threads, Lube Rod Bolts
After the rods have been cleaned, lubricate the bolts and threads for proper torque and smooth assembly. Bolts should be lubricated with SAE 30-weight engine oil. Just a light film of lubricant is all that’s necessary.
Step 24: Torque Rod Cap Screws (Torque Fasteners)
I don’t recondition cracked powdered-metal connecting rods the same way I do forged rods. First, you torque bolts to 18 to 25 ft-lbs, which loads the cap and bolts. Then you’re ready for reconditioning, which involves honing the bearing bore .002-inch oversize for an oversize bearing.
Using a torque-to-yield gauge, tighten the rod bolts 85 to 95 degrees.
Step 25: Measure Rod Journals (Precision Measurement)
Check rod journal sizing before any machine work begins. Rod journal bore size should be 2.234 to 2.240 inches (56.756 to 56.876 mm).
Step 26: Hone Rod Journal
Hone the large end carefully until proper inside diameter is achieved. Hone to .002-inch oversize for oversized (outside diameter) rod bearings. The difference between this and conventional forged-rod reconditioning is that you don’t cut the cap; you just hone the bearing bore .002-inch oversize. It is very important to have the right amount of bearing crush.
Step 27: Crankshaft Machine Work
Crankshaft machine work could mean micropolishing or grinding to the next undersize depending on journal condition. This nodular iron crankshaft is in perfect condition, requiring only micropolishing. When crank journals are scored, you must grind them to the next undersize, normally .010 inch, which calls for a .010-inch oversize bearing. The greatest oversize you should ever go to is .020 inch.
Step 28: Micropolish Crank Journals (Professional Mechanic Tip)
Micropolishing involves a sanding belt and a revolving crankshaft. The crankshaft revolves while the belt rides on each journal. Go with standard-size rod and main bearings.
Here’s the outcome from micropolishing. Next, chamfer oil holes to improve flow across bearings and journals. Chamfering opens up the oil hole so the flow is less restricted.
Step 29: Dynamic Balancing
Bob weights simulate reciprocating weight when you balance the crankshaft.
When you recondition connecting rods, you do the same thing you do with main bearing saddles in the block: resize the large end of the connecting rod. First, you disassemble the connecting rods, keeping each cap with its rod forging. You resize connecting rods because the large end of the rod becomes egg-shaped over time from reciprocating motion. The harder you work an engine, the more pronounced this distortion becomes.
Resizing or reconditioning the connecting rod involves milling the cap and the rod, and then resizing the journal if you have conventional two-piece rods. However, cracked powdered-metal connecting rods are one-piece components, which calls for honing to .002-inch oversize with oversize (outside diameter) rod bearings.
Regardless of whether your engine is a bone stocker, high-performance street motor, or racing engine, you should always spend money for dynamic balancing because it allows the engine to operate at maximum efficiency. In reality, dynamic balancing removes the shake from an engine by balancing all reciprocating and rotating mass. Vibration is mechanical oscillation around a central point such as an axle or a crankshaft. Reciprocating mass combined with rotating mass is more complex.
You want pistons and connecting rods (reciprocating mass) to “dance” on a crankshaft, which is counterweighted to keep both reciprocating mass and rotating mass smoothly in motion. When properly dynamic balanced, the piston, rings, and connecting rod are exactly the same weight as the counterweight. Of course, it is virtually impossible to get reciprocating mass to the same exact weight as the journal and counterweight because the technology isn’t that precise. However, you can get it to within .1 gram if you work at it long enough. This costs money, but it’s definitely a worthwhile investment.
When engines are manufactured, they receive Detroit balancing, which is based on groups (called lots) of pistons and rods. The factory standard is usually to be within 5 grams. But that’s not what you want for your Modular engine. Modular engines have an inherent vibration issue that surfaces around 2,000 to 2,500 rpm, which is where these engines normally operate. You want the balancer to tune out this vibration with exceptional balancing effort. Free of vibration, your Modular engine lasts longer, runs smoother, and, of course, makes more power.
Step 30: Balance to the Lightest Component (Precision Measurement)
When you balance an engine’s internals, you find the lightest piston and modify all eight pistons to that weight (because it corresponds to the crankshaft counterweight). Weight reduction comes when you drill and remove aluminum from seven pistons to get the weight down to that of the lightest piston/pin. Rings should always be included in the weight package. Ideally, you get all reciprocating mass to within .1 gram. Most builders are happy with 1/2 or 1 gram. You want .1 gram, taking precision balancing to new dimensions.
Step 31: Precision Balancing by Professionals (Precision Measurement)
Revco Automotive Balancing in Southern California performs extraordinary balancing technique with high-tech equipment. Here you learn where weight needs to be added or removed.
Step 32: Word from the Wise…
Marvin McAfee of MCE Engines in Los Angeles stresses the importance of dynamic balancing. He says it’s the vibration you don’t feel that can damage an engine. MCE Engines has tough balancing standards, which require weighing components to .1 gram. MCE Engines trusts only Revco Automotive Balancing for its balancing work. In fact, Marvin begins his own balancing work in his shop on his own scale, then, hands it off to Revco.
Modular engines represent a new generation of V-8 power, including the oiling system. The Modular engine is pressure fed for splash and spray lubrication, which is just like engines built during the past 100 years. For generations, the weakest link in the system was the fact that the camshaft drove the engine oil pump. Ford switched from a camshaft-driven to a crankshaft-driven oil pump for reliable and consistent lubrication. The Modular engine’s oil pump straddles the crankshaft for a rocksolid system of pump propulsion.
You don’t often think of oil pump and machine work in the same sentence, but a new oil pump should always be blueprinted, which consists of disassembling it and checking clearances. You should also check relief valve operation. The rotor side clearance is the most significant issue. Too much clearance and you have low oil pressure. Not enough, and you have pump seizure. Your machine shop should disassemble the pump and check these elements. Never use an oil pump right out of the box.
Headwork for the Modular V-8’s aluminum heads isn’t any different than it is for conventional overhead valve engines. Because these are aluminum heads, they already have steel valveseat inserts. Excessively worn valveseats must be replaced. These heads also need a conventional three-angle valve job for the street.
Never do a valve job on the cheap. A valve job should always include new stainless steel valves. Old valves can be refaced to “like-new” condition and live for 100,000 miles, but valvestems cannot be reconditioned. New guides compensate for worn valvestems, but you tend to lose something along the way, so if necessary, replace the valves. New stainless steel valves don’t cost much more than about $10 each from Federal-Mogul’s Speed Pro division. And you can expect reliability and peace of mind with 16 factory-fresh stopcocks.
You need a three-angle valve job for street use. If you’re going to run an engine hard, for example as a road racer, you want good flow, but you want plenty of good valveseat contact for valve cooling. Multi-angle and radius valve jobs improve flow but reduce valveseat contact, which causes valves to run hotter and wear out sooner. So it’s always a compromise between performance and reliability. Performance sometimes comes at the expense of reliability. And without reliability, you are dead in the water. Spend the money for a good valve job; it’s worth it.
Cylinder head refacing (milling) should be performed only if it is absolutely necessary. Each time you mill a cylinder head deck surface, you change a couple of important things. You make the deck thinner, which adversely affects integrity. You also make the combustion chamber smaller, which increases compression. It may also cause unwantd valve shrouding. Ask your machine shop whether your heads need milling, and if so, request that the smallest amount of material possible be taken off.
Viton valve seals are another important upgrade. They are better than Teflon seals for street use because they simply outlast Teflon seals by a wide margin. Viton seals allow for a smooth yet controlled flow of oil to the valveguides.
Step 33: Disassemble Cylinder Heads (Documentation Required
Disassemble a pair of 4.6L SOHC heads using a 3/8- inch-drive ratchet and 12-mm socket. These are Romeo heads with cam girdles for strength. The first things to come off are the girdle caps. Take note of where they go and mark them accordingly. They should go back in the same place.
Step 34; Get to Know Modular Cylinder Heads
With the girdle caps removed, SOHC architecture is easy to understand. This is a very simple design where large, composite cam lobes ride stamped steel roller rocker arms. These rocker arms are designed to withstand 10,000 rpm. Cam lobes are large to reduce internal friction and allow for a more aggressive profile.
Step 35: Inspect Camshafts (Precision Measurement)
Inspect each camshaft and mark it left or right. Also mark each head left or right. These are good, reusable camshafts with virtually no wear.
Step 36: Inspect, Measure, Chamfer Cam Journals
Cam journals ride in these saddles without bearing shells. With this oilpressure-fed design, there’s virtually no wear for the life of the engine. I suggest chamfering the oil holes as part of your machining regimen. Allowable journal diameter is 1.060 to 1.061 inches (26.936 to 26.962 mm). Journal-to-saddle clearance should be .00098 to .003 inch (.025 to .076 mm). Allowable endplay is .00098 to .0065 inch (.025 to .165 mm).
Step 37: Remove Tappets (Important!)
Hydraulic cam followers work just like hydraulic lifters in a pushrod engine. They maintain valve lash via oil pressure. Remove cam followers (also known as tappets or slack adjusters) and take note of their position because they’re reusable. If you’re going to reuse tappets, they must go back in the same bore. Rocker arms should go back in the same position as well. Tappet diameter is .660 to .629 inch (15.988 to 16.000 mm). Tappet-to-bore clearance should be .00071 to .00272 inch (.018 to .069 mm).
Step 38: Remove Valves and Springs (Special Tool)
Compress the valvesprings with a compressor tool and remove the keepers. The Modular engine has small motorcycle-size valvestems and springs to reduce reciprocating weight. It takes less energy to open and close these valves, yet they deliver good flow because valve face size hasn’t changed much. A conventional valvespring compressor does not work. You need special tools from Ford: PN 303-381 (T91P-6565-A) and PN 303-382 (T91P-6565-AH).
Step 39: Measure Valvestems
Measure the valvestem length and record it before valve faces and seats are machined. Valvestem diameter should be .2750 to .2746 inch (6.995 to 6.975 mm) for the intake and .2740 to .2736 inch (6.970 to 6.949 mm) for the exhaust.
Step 40: Mark Oil Galley Plug Locations
Remove the oil galley and cooling system plugs for cleaning. Mark each plug location with a permanent notch so galley plugs go back where they belong. If you get it backward, you’re looking at a huge mess and a lot of labor, because at the least, you have to pull cylinder heads. Take careful note of oil galley plug locations.
Step 41: Clean Valvetrain Parts
This JGM Performance Engineering parts tumbler rolls parts through a solvent/metal shot combination for exceptional cleanliness. Valves, retainers, and springs come out like new.
Step 42: Reface Valves and Seats (Important!)
Coat the valves and seats with Prussian Blue dye so you can see the cut. As cutting or grinding takes place, Prussian Blue is removed, revealing the cut. Valve face angle should be 45.25 to 45.75 degrees.
Step 43: Measure and Machine Valvestems (Precision Measurement)
Measure the valvestems with a micrometer and machine them to clean the surfaces. This process removes any irregularities and burring. Valvestem diameter should be .2750 to .2746 inch (6.995 to 6.975 mm) for the intake and .2740 to .2736 inch (6.970 to 6.949 mm) for the exhaust. Discard any stems that are out of spec.
Step 44: Do the Right Valve Job
Grind the valve faces. Prussian Blue offers a sharp contrast, revealing seat width. Street engines should receive a standard three-angle valve job because you want good seat width to enhance valve cooling. The more seat contact you have, the better the valve cooling. Drag racing engines should receive at least a five-angle valve job for improved flow where cooling isn’t as critical.
Step 45: Perform Valve Job (Performance Tip)
Perform a standard three-angle valve job with this cutter, which cuts all three angles at the same time. A threeangle valveseat offers excellent sealing and valve contact, which aids valve cooling. It does not offer the same kind of flow experienced with a five-, seven-, or radius-angle valve job. When flow is more important, you go with more angles.
Step 46: Mill Cylinder Heads
This mill is set up for head resurfacing. Machine shop costs are rooted mostly in setup time. This is why machine work is so expensive.
Step 47: Milling the Head (Professional Mechanic Tip)
Make the first pass with the mill, cutting .005 inch first, checking for imperfections. Rarely does the first pass remove all irregularities, but never mill more than .010 inch.
Step 48: Mill for Perfect Surfaces
It’s not likely that you will achieve a perfect surface on the first pass. Low and high spots are easy to see. The second and final pass perfects the surface. Milling heads makes combustion chambers smaller, so plan for an increase in compression. This is one reason you need to know chamber volume before choosing a piston. If you have the luxury of time, have your head work done before selecting a piston.
Step 49: Check Valvestem Length (Precision Measurement)
Check the valvestem length with the refaced valves and seats. Stem length is longer because the valve head is deeper in the seat, which means the technician has to grind the stem tips to get the valve length back to original size. As valves and seats wear, the same thing happens.
Step 50: Use Viton Valve Seals (Professional Mechanic Tip)
Although Teflon valve seals are popular with many builders, this Viton seal from Fel-Pro is the best seal for street/strip use. It is an extremely durable valve seal that offers excellent sealing and oil control. Use Ford special tool number 303-383 (T91P-6571-A) to install valve seals.
Step 51: Install Valve Retainers and Locks
Lubricate valvestems and guides with engine assembly lube. Install new valve locks along with original retainers. A good rule is to install new valve locks (keepers). You need Ford special tool numbers 303-381 (T91P-6565-A) and 303-382 (T91P-6565- AH) to compress the springs.
Step 52: Prep and Install Valve Tappets
Wash the hydraulic tappets (slack adjusters) in solvent and soak in engine oil. They’re primed and ready for installation.
Step 53 : Install Camshafts
Bathe the cam journals in assembly lube; then they are ready for cam installation. First lay in the camshaft, setting it up at the 11 o’clock position to prevent valve damage when the heads are installed. Give each head the same treatment. Forget this step, and you will bend valves just installing cylinder heads. Romeo heads receive girdles (shown). Windsor heads have individual journal caps. You need Ford special tool number 303-557 (T96T-6256-B), the camshaft-holding tool. You need two of them to maintain the proper camshaft position during cylinder head installation.
Step 54: Torque Cam Retainer Bolts (Torque Fasteners)
Torque the cam girdles to 15 to 22 ft-lbs on Romeo engines and 6 to 9 ft-lbs on Windsors. Torque the girdle as you would a cylinder head: from the inside out, using oil on the bolt threads. Remember to chase all bolt holes and check threads for damage
Written by George Reid and Posted with Permission of CarTechBooks