How-To Build A Ford Mustang Engine Right
Avoiding The Faux Pas That Can Cost You Plenty
Engine-building tends to be a mystery for most of us. We're baffled by the tricky math that goes with machine work. And sometimes we're stumped when it's time to buy parts, not to mention assemble an engine. So what to do? Well, listen up, because it's time to go back to school--engine-building school, that is. We're not necessarily going to show you what to do here, but what not to do when building and setting up an engine. Some of these great ideas come from our own past heroic failures and faux pas-and yes, we did learn from them. We also received help from Tom Naegele at D.S.S. Competition Products, Jon Enyeart at Pony Carburetors, and the fine folks at Crane Cams. Thanks, guys!
Neatness CountsWhen it's time to disassemble an engine, we tend to get sloppy because it's dirty work. But you must be organized from the start. Don't throw all of the parts in one big box and hope for the best later on. Inventory your parts and keep them in proper order. If you're going to reuse any parts, they must go back in their proper place; only a few of us put them back where we found them.
Balancing ActWe get this one mixed up a lot: dynamic balancing. Small-block Fords were externally balanced two ways from the factory: 28-ounce offset and 50-ounce offset. Get this one wrong and we won't need to talk about dashboard chatter-you'll live it. Small-block (260, 289, 302) Fords manufactured prior to 1982 were 28-ounce offset-balanced. When reciprocating weights (rods and pistons) became heavier in 1982 with the 5.0L H.O. engines, offset balance increased to 50 ounces. This means you can't use a 5.0L H.O. flywheel/harmonic balancer on your pre-'82 260, 289, or 302. It also means you can't use a pre-'82 260, 289, 302 flywheel/harmonic balancer on a 5.0L H.O. Small-block Fords are externally balanced, which means the flywheel and the harmonic balancer must be balanced with the crank, the rods, and the pistons.
Rocker ArmsMost often, engines die due to valvetrain failure. Many of us have a tendency to install pushrods and rocker arms without checking the harmony between the rocker arm, the pushrod, and the valvespring beforehand. The folks at Crane Cams recommend that you take the time to check the harmony prior to fire-up. The rocker arm must sit squarely on the valve stem, and it should be relatively level in relation to both the pushrod and the valve stem. With the valve fully open (at peak lift), the rocker arm tip should be clear of the valvespring retainer. Overlook these basic tasks and they can bite you in the-well, you know.
Checking The DeckOnly a few of us check the cylinder head and block deck surfaces for trueness. Warpage in these areas can cause a blown cylinder- head gasket, leakage, or both. Make sure you check these surfaces and mill as necessary.
Mystery OverheatsIt's such a simple issue, but we've screwed up the engine's head gaskets more than any other head gaskets. Engines overheat when we install their head gaskets backward. FRONT means front on every application. Head gasket cooling passages must be positioned at the back of the head/block in order to have coolant flow throughout the entire engine. If the passages are positioned in front, coolant doesn't circulate to the rear of the engine, thereby causing major hot spots.
HousecleaningOnly a few of us thoroughly clean our engine castings during a rebuild, but oil and coolant passages must be thoroughly cleaned, no matter how long it takes. Crusty water jackets and clogged oil passages are engine suicide if they're not checked during an engine build. When you check water jackets, ascertain that all freeze plugs have been removed; ditto for oil galley plugs.
DustCoverKnow what kills fresh engines? Dust. When you're assembling an engine, make sure it's wrapped in a plastic bag when you're not working on it. We've witnessed early engine failure because engines were left uncovered by hobbyists and machine shops alike. Dust finds its way to the bearings, the cylinder walls, and the moving parts, which causes premature wear and tear, so cover it up!
Details, DetailsYou know the old saying, "Never enough time to do it right the first time, but plenty of time to do it over." Quite often, we're guilty of being eager to get the car finished and get into it. But in being eager, we miss important details that would take seconds to accomplish and save us a lot of grief. Naegele recommends you check bearing clearances twice. Go back and retorque the rods, the mains, and the heads thrice, marking each bolt head with a marker as you go. You'll sleep better if do you.
Crack CheckOnly a few of us get this one right until we experience the agony of an engine build gone bad. Check for cracks before the heavy expense of machine work. Locating the crack after machine work may save you the grief of engine failure, but it's still an expensive oversight that means redundancy and even more cash flow.
Blazing SaddlesThe main bearing saddle alignment gets overlooked more than anything else during an engine rebuild. Have someone at the machine shop check the line bore before pressing ahead to any other machine work. And if necessary, have him bore and/or hone the main bearing saddles. This gives your crankshaft a comfortable spot in which to sit, which means less wear and tear on the main and rod bearings.
Clean Up!It's easy to take for granted that the folks at the machine shop have performed a stellar clean-up job on your engine's block and heads. Oil and cooling passages must be clean. Make sure the oil passages are clear from stem to stern and the cooling passages are free of rust and iron particles. Look at the crud in the water jacket on this rebuild we witnessed in one Los Angeles machine shop! Examine your castings before the engine is assembled.
Keep Your SeatTwenty years ago we were worried about the absence of lead in gasoline because lead served as a valve seat lubricant in the old days when iron cylinder heads had iron exhaust valve seats. The sky didn't fall after all, because unleaded fuels have served to clean up the air and our engines. Still, too few of us are installing hardened steel exhaust valve seats during our rebuilds to ensure longer cylinder head life. Don't forget to install hardened exhaust valve seats whenever the heads come off.
More Isn't BetterToo much silicone sealer can harm your engine. Why? When too much silicone sealer is used, it can block oil and cooling passages, thereby causing hot spots and definitely dry spots. Globs of loose silicone sealer follow a path to the radiator, thereby plugging the cooling tubes and causing overheating. Loose silicone can also find its way to the oil pan and end up plugging the intake screen and limiting oil flow. Just a dab will do. Use a thin film of sealer on just one side of a gasket surface, then install the part. Use silicone only at cooling passages and in areas where oil may leak. Intake ports don't need it.
Backward?You wouldn't believe the number of engines that get assembled with the main and/or rod bearings installed backward. Nagley told us, "Check for the bearing tab's location during installation. There shouldn't be any oil between the bearing and the saddle or rod. Seat the bearing snugly, and make sure the oil holes are aligned correctly. Cam bearings are especially easy to install incorrectly. Check the oil holes for correct alignment in all applications."
Lube The LobesAll camshafts should be lubricated during installation. Only a few of us get this one right. Flat-tappet camshafts need lots of lubrication, then a good, 20-minute warm-up at 2,500 rpm, according to Crane Cams. Roller tappet camshafts don't need the warm-up lap, but they do need lubrication. Make sure all journals and lobes are covered with assembly lube before fire-up.
Getting It Right For 1967Did you know that 1967 was an odd-duck year for Mustang V-8 engine mounts? Before mid-1966, Mustangs had doughnut-style V-8 engine mounts. In mid-1966 Ford redesigned the Mustang V-8 engine mount to create a saddle affair, which allows the engine to sit lower and the mounts to take up more vibration. It may surprise you to know that the '67 Mustang V-8 engine mount stands alone from the '66 and the '68-'70, because-dimensionally-it's a different mount. How do we know this? From hours of fighting with a duo of aftermarket engine mounts our auto parts store said would fit on a '66-'70 Mustang or Cougar.
When we visited with Cecil Myers at Mustangs Etc. in Van Nuys, California, he told us the '67 Mustang and Cougar stand alone when it comes to small-block engine mounts. For the '67, the 289 gets two D0ZZ-6038-B mounts where the holes are positioned 11/44-inch differently from the '66 and the '68-'70. What's more, the mount and the bracket are geometrically different. Apparently, Ford engineered new dimensions for 1967, then had a change of heart back to the '66 dimension for 1968. If you have either a '66 or a '68-'70 Mustang, aftermarket mounts will fit just fine. If you have a '67, you'll have to opt for D0ZZ-6038-B mounts, which currently retail for approximately $100 each. One way to get out of this is to install '68 Mustang engine mount brackets in your '67 and use '66 or '68-'70 mounts. Just don't forget that's what you did later on.
Degree For LifeFew of us who build our own engines think about degreeing the camshaft during assembly. But degreeing a camshaft tells us more than just camshaft specs, according to Crane Cams. It also tells us about crankshaft, piston, and rod integrity. Degreeing in a camshaft confirms camshaft specifications one way or the other. It also helps us determine piston position as it relates to the camshaft. In a world where we take a lot for granted, this is one area we should never overlook.
Oiling UpgradesThose of you who are building 351C, 351M, or 400M engines aren't always taking care of business during your buildups. Although it's unlikely you'll ever see a 351M or a 400M small-block in a Mustang, you can count on a 351C as a possible option from 1970-'73. These engines suffer from oil starvation at the No. 4 and the No. 5 main and rod bearings. What to do? The simplest answer comes during a rebuild. Install an oil galley restrictor plug between the No. 1 main and the No. 1 cam bearings to reduce excessive oil flow in front and to allow more volume and pressure at the No. 4 and the No. 5 main/cam bearings where it's needed more. The folks at the machine shop can help here. If your engine is already installed, another solution is to run an external line between the front and the rear oil pressure sender ports, which gets more oil to the No. 4 and the No. 5 main/rod/cam bearings.
When Not To GrindToo many of us grind crankshafts when we don't have to. If your engine has had a healthy service life (plenty of oil changes), you don't always have to grind the crankshaft to the next size under. If the journals look good, simply have your machine shop polish then measure them, and size permitting, fit standard bearings to that healthy crank.
Wet Or Dry?One question we hear time and time again is, do I torque fasteners wet or dry? If you're interested in an accurate torque reading, then putting a thin film of lubrication on the threads of bolts and nuts is a good idea during an engine assembly. Dry fasteners can bind, giving you an erroneous torque reading, but slippery threads won't lie.
Use A Torque WrenchBelieve it or not, some machine shops and production line rebuilders don't use a torque wrench during engine assembly. They run fasteners down with an air impact and hope for the best. Call this shooting craps with a blindfold on in a casino full of thieves; you may or may not get lucky. We torque engine fasteners to determine proper bolt stretch. When we overtighten, we risk warping castings or breaking fasteners. When we don't give it enough torque, we risk the whole monkey works coming unglued. Why torque? Because you want to be right the first time.
Got Lube?A few of us are guilty of assembling our engines using SAE 30-weight engine oil as an assembly lubricant. But engine oil doesn't have staying power, especially if the engine sits for several months before fire-up. According to the folks at D.S.S. Competition Products, you should use assembly lube on the main, rod, and camshaft journals. Assembly lube protects all moving parts from unwanted friction during that first fire-up. Bathe the cylinder walls in assembly lube during piston installation, and smother every moving part in the lube during assembly.
Spring Height?Only a few of us do our homework, or should we say our "headwork." When you're performing a valve job, don't forget to do all of the math while you're at it. It's a good idea to check valvespring height and pressure during an engine build. After all, you want to make sure your valvesprings and camshaft profiles match in every way. And you want to make sure there's no coil bind if you're running an aggressive camshaft. Checking it now means not having to say you're sorry to the family member who writes the checks. Most cam manufacturers, such as Crane Cams, have all the information you'll need to check this out too.
Check The GapOne shortcoming we see repeatedly is piston-ring end gaps. All of us aren't checking piston-ring end gap during our buildups. Sometimes we check one cylinder just to ease the conscience. But we'll tell you this: no two cylinder bores and no two sets of piston rings are alike. Naegele informed us, "Check every single set of compression rings and match each set to the bore. Running a tight ring gap can cost you plenty when the engine gets warm. Running a loose gap can hurt compression and ring sealing. And don't forget to position those ring gaps 45 degrees out from each other while you're at it-at 9, 12, 3, and 6 o'clock."
Seal The DealCoolant escapes from water jackets more times than not, because we fail to use bolt thread sealer during assembly. This is especially important when we have a "wet" deck where the head bolt threads into the water jacket. Use ARP thread sealer whenever you're in doubt; then sleep comfortably.
Use The Right HeadYou'd think we'd have this down by now, but we don't. If you're building a hot FE big-block for your '67-'70 Mustang, don't forget to use the appropriate cylinder heads. FE heads designed for the Mustang, Cougar, Fairlane, and Comet have four exhaust-manifold bolt holes (shown). If your custom-built 390 High Performance has '61 C1AE Hi-Po heads, you're going to kick yourself when it's time to install the headers, because those very necessary bolt holes won't be there.
Overcarburetion!You'd be amazed at how many rides we see out there with huge carburetors overfeeding modest engines in need of less. According to Jon Enyeart of Pony Carburetors, "If you have a stock 289 or 302 4V engine, you don't need more than 500 cfm; if it's a 351W, no more than 550-600 cfm. Big-blockers in the 390-428ci range need only 600-650 cfm to get the job done. We know Ford put 735-cfm carburetors on 428 Cobra Jets, but these engines didn't need that much carburetor. A 428 Cobra Jet can get by with 650 cfm, believe it or not. In fact, you'll achieve better low-end torque with a smaller Holley; no foolin'."
Have You Heard This One?You may think this is impossible, but it's possible to get small-block Ford connecting rods mixed up. At first glance, 221, 260, 289, and 302 connecting rods look the same. You'd be surprised how many 302 rods wind up in 289 engines and vice versa. The problem is that we run into piston height issues either way. The 221, 260, 289 rod is easily identified as the C3AE forging, while the 302 rod is the C8AE forging. Remembering this important fact will save you a lot of grief. By the same token, remember that the 221, 260, 289 crankshaft is identified with a "1M," whereas the 302 crank is a "2M" casting. Rods and cranks must be compatible.
Use A Torque PlateNot all machine shops use torque plates when boring and honing blocks, but yours should. "The torque plate is a steel plate bolted to the deck of the block during boring and honing to simulate cylinder head stressing," said Naegele. "We want the cylinder bores machined and honed as though heads were installed for optimum results. If we bore and hone a block without the torque plate, cylinder dimensions will change when we install the heads, which can adversely affect the piston-to-cylinder wall marriage."
Cam Bearing 101Do you know what kills an engine more quickly than anything? Oil starvation. Oil starvation occurs when we install the cam bearings incorrectly and forget to line up the oil holes. Laugh if you will, but we see this time and time again, and it's darned costly. Someone gets in a hurry during assembly and doesn't check oil galley hole alignment in the cam bearings. Oil must be able to pass from the filter to the cam and the main bearings or it gets real ugly real fast. Always double-check cam bearing oil passage alignment before assembly begins.
Checking ClearancesYou'd be surprised at how many engine builders finish a job up, only to discover an unexplainable rapping noise in the pan during fire-up. Today's oil pump castings aren't always kind about clearing the crankshaft counterweights in small-block Fords. Sometimes the counterweight brushes the oil pump. This is a very important clearance you'll want to check. Make sure the pump clears the counterweight by at least 0.040 inch. This will allow for expansion as the engine warms up.
We hope these tips will prevent you from destroying your engine. We also hope they will make your engine perform as Ford intended or, if your aim is modification, better than Ford envisioned.