Engine-building technology has made huge advances over the past thirty years and the 335 Cleveland engine family is no exception. Cylinder head and cam technology have come a long way just to name two areas. Small details can make or break an engine build regardless of technology. The biggest two I can think of are checking clearances and workmanship, again and again. Far too many of us learn the hard way because we’re not attentive enough to detail.
We get in a hurry to finish and hear it run missing important detail in the process. We learn when an overlooked rod bolt fails halfway down the track. And we learn when a carelessly seated valve keeper escapes at high revs.
This Tech Tip is From the Full Book, FORD 351 CLEVELAND ENGINES: HOW TO BUILD FOR MAX PERFORMANCE. For a comprehensive guide on this entire subject you can visit this link:
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Once you understand what you want your Cleveland to do, you can plan the engine’s basic architecture beginning with good bones. You’ve got to know what works well together and what doesn’t. The right block and head combination. A solid bottom end (crank, rods, and pistons). A cam that works well with all of these components and for your driving agenda.
Even if you’re building a warmed-up stock Cleveland with a factory crank and rods along with hypereutectic or forged pistons, you need to know your engine’s physics. Again, I am going to presume you’ve got no larger than a 4.040-inch bore. There are sticky issues such as compression height, swept volume, piston dimensions, and chamber size to think of. You can wind up with too much or too little compression. Knowing these issues going in, you can know almost exactly what your Cleveland is going to do when it’s fired.
Planning is the most effective engine building tool you can have. Far too many engine projects fail because there isn’t proper planning. At the least, these projects produce disappointing results because you don’t amass the right combination of parts and technique. Time and money are wasted when you don’t think about what you want the engine to do. A big part of building an engine is knowing exactly what you can afford, then not giving in to ego and temptation. In other words, be truthful and realistic with yourself. That’s the mistake a lot of us make along the way. We want to impress our peers. But this isn’t the right reason to build an engine. Don’t build an engine to impress anyone besides yourself.
Every engine-building project should begin with a realistic plan. You wouldn’t build a house or landscape your backyard without a plan would you? What do you want your engine to do? Forget the notion you can build a radical racing engine for the street and use it for the daily commute because, no matter what the buff magazines tell you with “800 Streetable Horsepower On Pump Gas” claims, it is a long shot mixing street and race experiences without conflict. There are strictly street engines, weekend bracket racing engines, and all-out racing engines. Street and weekend bracket racing mix as long as you achieve a nice balance of the two.
Daily driver/weekend race engines need a civilized street attitude to where your teeth aren’t being jarred at a traffic light yet you can crack a 13-second quarter-mile on Saturday night. And yes, this is doable using a large amount of common sense. Street engines need to be designed and built for torque, not horsepower. Horsepower is a high-RPM wide-open throttle, maximum power on a racetrack event. Torque is the real street power that gets you going out of a traffic light and onto the freeway. Weekend horsepower should be realistic with the peak coming somewhere around 6,000 rpm and torque at 4,500 rpm. In the real world, you want a broad power band on the street where torque begins to come on strong around 3,000 and peaks at 4,000 to 4,500 rpm. This enables you to snuff out upstarts at traffic lights and achieve good quarter-mile elapsed times, yet have something you can live with daily. Of course common-sense gearing and your driving ability are the rest of it.
A plan begins with a foundation on which to build expectations. First, what horsepower and torque numbers do you expect and what can you afford? No use in dreamy-eyed bench racing where you’re expecting 600 hp and 550 ft-lbs of torque with a modest budget and a daily commuter street plan. On the street, 400 to 450 hp is plenty along with more than 400 ft-lbs of torque. It is also affordable if you plan and execute properly. And no matter what big-talking bench racers say, you don’t need any more than 450 hp/400 ft-lbs on the street.
I 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 place. Keep engine parts and fasteners in jars or plastic containers 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 the project moving. If you cannot afford a machine shop at this time, leave the engine assembled until you can. (I 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. 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 money.
When it is time to assemble the engine, you must have a hospital-clean shop. Even simple house dust (which is actually dead human skin cells and decaying matter) damages an engine’s mating surfaces. House dust scores bearings, journals, and cylinder walls. 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 damages engine parts. Keep this kind of work away from your engine. Make sure engine assembly lube and oil are pure and clean. Any kind of stray matter, no matter how small, damages your engine.
Mark and Clean Parts
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 miked and honed to the piston. Each piston should be numbered to the bore that was honed for that match, not to mention dynamic balance. 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 the extreme. Number each cylinder with a felt-tip marker at the block deck. Lay pistons and rods out on the bench in cylinder number order. Get acquainted with piston domes prior to assembly, especially with a Cleveland. (You would be amazed how many engine builds I’ve witnessed where the pistons were installed upside down. One of them actually made a magazine cover that way.) Keep spray cans of brake cleaner on your workbench to give a last-minute clean to parts during assembly. This eliminates any chance of dust particles and stray matter where it doesn’t belong. Use lint-free tack rags (static cloths) for your last-minute clean-up work. Do not use those cheap and linty shop towels, terry cloth, or paper towels for engine assembly. Keep plenty of engine oil and assembly lube close by. Keep these items covered to keep dust and debris out.
Begin your Cleveland project with healthy parts. Because Cleveland engines have a reputation for fl awed castings, you must be very cautious when selecting yours. If you’re buying a junkyard core, get a written money-back guarantee. First thing to do is inspect a potential core for obvious issues—leaks, cracks, overheating, voids in castings, and poor workmanship.
Rarely is poor workmanship found in original factory-assembled engines (though it has happened). You do, however, find plenty of it in rebuilt or remanufactured engines. Incorrect parts, reused defective pieces, poor machining and assembly techniques, and the absence of maintenance all play into why an engine fails. Disassembly is a forensics experience where you get to learn all about the engine’s recent past. Sometimes, you have a salvageable core. Other times, you have junk. You never really know what you have until you measure cylinder bores, clean castings, and do magnetic particle inspection to check for cracks.
Of course you need to inspect the crank, measuring journals and checking for runout. Also check for irregular wear patterns. Ditto for connecting rods, checking them for abnormal wear, trueness, and journal dimensions.
Written by George Reid and Republished with Permission of CarTech Inc