Last month, we introduced you to Blair Jennings of Santa Barbara, California ("Eight Barrels-No Waiting," Mar. '06). When Blair started planning his '66 Mustang fastback project car more than five years ago, his vision was to build the ultimate street driver's car-a road racer with streetable qualities. He wasn't thinking about your typical restomod with a fancy stereo system, late-model seats, air conditioning, or plush surroundings. He wanted a real driver's car-doable for the street yet ready to go road racing at a moment's notice. And he wanted more than 600 hp and an equivalent amount of torque. It had to have Weber carburetors and a dry-sump oiling system, and it had to be fast.
When Blair rediscovered a family friend of his from 35 years ago, Marvin McAfee of MCE Engines in Los Angeles, he knew that based on his father's great experiences with Marvin, there was only one guy to build his 427W. Marvin knew exactly who Blair was and invited him to his shop. When Blair arrived with a stillborn 427W in pieces, Marvin knew he had a challenge before him.
Blair spent a fortune amassing parts for his engine. Marvin, however, was certain Blair didn't have the optimum combination of parts. The cam was too radical for street use-sacrificing low- to midrange torque, idle quality, and intake manifold vacuum. Those Weber 48IDA carburetors looked terrific, but they were too much carburetor for what Blair had in mind-a whopping 2,540 cfm with the throttle to wood. Marvin also questioned the need for a dry-sump oiling system when a deep-sump road-race pan would have worked just as well for street and weekend road racing.
Marvin didn't have the heart to suggest Blair sell most of what he had brought in. So, he and the MCE team evaluated Blair's parts and figured out how best to pull it off. Based on Marvin's computer analysis of the parts, MCE had a 600-horse 427W in the making. It was probably more power than Blair needed. The greatest challenge was how to make it tolerable for the street without breaking anything. You see, Blair wanted 600 solid horses and an equivalent amount of torque, but he didn't have a driveline that would take it.
This engine combination requires a clutch capacity of at least 700 lb-ft, accompanied by a well-built Ford Top Loader four-speed, a 9-inch Ford rearend backed up with a pair of heavy-duty Spicer universal joints, and a balanced driveshaft.
So what can we learn from Blair Jennings' 427W experience? We learn how important it is to do your homework before committing to anything. Like us, Blair is a typical Joe Six-Pack kind of guy who ordered parts based on his perception of how to build a car. We have learned the hard way in our car-building efforts how much a bad decision can cost us. This is where Marvin McAfee has the edge called experience. It teaches us what works and what doesn't. It's why MCE Engines generally doesn't build anything unless it has approved all parts. It's a policy born of hard-won experience. So let's address the learning curve of Blair's 427W.
Blair purchased a dry-sump pan that didn't fit his Mustang fastback. That's when Marvin designed a custom dry-sump system for him. Once Marvin generated the line drawings, he contacted Canton Racing Products in Connecticut. Doug Vine at Canton got Marvin dialed in with a superb, custom-made aluminum dry-sump pan for Blair's 427W.
This is the custom designed and fabricated dry-sump pan from Canton Racing Products. In this case, Marvin did the designing and Canton followed his specs. Note the careful thought given to oil scavenging-a windage tray designed to fit the Canton main stud girdle, which channels return oil to scavenge ports and is designed to handle hard acceleration and extreme lateral G-forces.
Marvin's experience teaches us about things most of us never think of. Just because a stud girdle is fresh out of the box doesn't mean it's ready for permanent installation. Each and every main stud girdle's fit is based on what you have for a crankshaft, block, and connecting rods. This is why he stresses checking clearances on everything before final torque.
Marvin builds engines like seasoned street rod builders plan and execute street rods. First, he does a mock-up. In fact, he does several mock-ups just to be sure it's right.
Marvin checks girdle clearances, stressing there should be a minimum of 0.060 inch between moving parts and the girdle. This is because of thermal expansion-as parts get hotter, they grow. He marks the girdle areas that will need machining to at least 0.060-inch minimum clearance.
How's It Slidin'?
What makes Marvin a cut above is his detailed, methodical approach to engine building. Have you ever had a part that needed a whack to fit? That's known as a pinch fit or interference fit. Pinch fit (no more than 0.001 inch) is acceptable to Marvin only when it is intended to keep a part secure, such as a distributor drive gear, a crankshaft damper, or a rear axle bearing. Cam and crank gears, for example, should slide on with finger effort. The key phrase is "slide on," which means a zero fit where parts fit without effort. According to Marvin, if you have to drive a cam or crank gear with a hammer, the fit is too tight. When zero fit doesn't happen, he massages parts until it happens. You should, too.
Life Without Leaks
How many of you have built a fresh engine only to have it leak oil on your garage floor or driveway? Because we all need to be environmentally responsible, any leakage is intolerable. You can achieve a leakproof engine if you sweat the details during assembly.
Where possible, Marvin installs one-piece seals prior to crank installation. One-piece sea
Did you know you can machine your two-piece-seal Ford block to accommo-date a one-piece rear main seal? If you're not up for that, did you know you can achieve a leakproof two-piece rear main seal? This is where Marvin sweats the details, never suffering the embarrassment of a leak. Remember, in both cases, the sharp lip must face inward to keep oil inside.
One-piece rear main seals are lightly lined with high-temp RTV silicone sealer around their circumference. Marvin does this before setting the crank. When he sets it, he uses high-temp RTV between the No. 5 main cap and block. He stresses allowing the RTV to set up for 24 hours before firing an engine for best results.
Two-piece rear main seals should be installed with gaps located out of synch with cap/block parting lines. In other words, stagger the gaps away from cap/block gaps. This virtually eliminates the risk of leakage. Use silicone between the cap and block as added insurance. Once cured, RTV provides a solid seal.
Other leak-vulnerable areas are the front main seal and the pan gasket. Marvin believes in modest amounts of sealer and only at areas susceptible to leaks. Where pan gaskets meet, end gaskets need silicone sealer. End gaskets need a super-thin layer of silicone to both stay put and keep oil inside. The same can be said for valve-cover gaskets. Use a thin film of sealer between the gasket and valve cover only-never between the head and gasket.
Another troublemaker is the camshaft's block plug in back. Again, apply a thin coat of silicone sealer around the perimeter, then ascertain security before installing the engine. Few things are more deflating than discovering a leaky cam plug once the engine is installed. Permatex's The Right Stuff is a terrific sealer, guaranteed to eliminate leaks. Try it on your next engine build. If you want to guarantee leakage, overtighten the valve covers, timing cover, and oil pan, which will distort the part and cause leakage. Always follow torque specifications.
Oiling System Priorites
There's a lot of urban legend surrounding Ford oiling systems. One basic truth holds our attention: Crankshaft main and rod bearings need more oil than cam bearings. MCE Engines installs oiling-system restrictors to cam-bearing journals at mains 2 through 5 to reduce oil flow, increase the flow to main/rod bearings, and reduce the flow to cam bearings. This increases the oil flow to main and rod bearings while still maintaining liberal oil flow to the cam bearings and valvetrain. Do not install an oil restrictor at the No. 1 main journal. Tap for oil restrictors during the block-machining process, which eliminates any chance of metal trash in the oiling system later on.
Marvin peens the manifold end-gasket rails for gasket security. This creates rises in the
Chamfering crankshaft-journal oil passages improves oil flow. There are two reasons for th
When Marvin does a mock-up, he finds all the pitfalls, such as rod-bolt clearance. If you
When Marvin performs a final assembly, he does the same thing he did during the mock-up, c
Marvin checks the Canton Racing scavenge pan for proper fit by MCE specifications. Pleasan
Inside, Marvin has eliminated the factory oil pump. With a dry-sump system, there is an ex
What's Up Top?
We don't give cylinder heads and valvetrains enough of our attention, but these are areas where engines fail most. Because valves and springs do one of the toughest jobs inside an engine, they mandate our every attention. Valve-stem-to-guide clearances must be spot on-not too tight and not too loose. MCE Engines recommends a window of 0.0015-0.0025 inch on stem-to-guide clearances. For intake, go with 0.0015 inch. For exhaust, push it more toward 0.0025 inch because the exhaust valve runs much hotter.
During assembly, Marvin uses Comp Cams assembly lube No. 153 over Dow Corning dry film lubricant No. 321 for ideal valve-stem lubrication for that first firing. Valve clearances can bite us in the butt if we're not diligent during assembly. Again-more of that mock-up stuff. Mock up your engine's cylinder heads and check clearances. How close are the valves to each other? How much clearance is there around the valve heads? What is piston-to-valve clearance? Have you checked all of them? Just because clearances are acceptable at one bore and chamber doesn't mean they will wash with the rest. No two chambers are the same, so don't expect them to be.
Marvin blueprints every part of every engine he builds. Valvesprings are massaged to elimi
Valve-to-valve clearances are checked-never to be smaller than 0.060 inch. Even if you hav
Valve stems are coated with Comp Cams Assembly Lube to ensure lubrication during startup.
Here, Marvin checks valvespring installed height to ensure the engine will reach the cam's
Valve-to-piston clearances are checked using clay in the valve reliefs as shown. Marvin ch
One thing we rarely get right in engine building is port match. Bad port matching robs pow
MCE Engines secures roller tappets like this, using safety wire to secure spider fasteners
Schneider shaft-mounted roller rockers are designed to take a seven-grand blast. What's mo
Marvin performs valve adjustment by the 427W's firing order. Valves are adjusted at the lo
Other Important Engine-Blueprinting Issues
Engine building is an art to be learned and perfected over a lifetime. This is what makes MCE Engines exceptional in a trade full of professed engine builders. Marvin will tell you "there are engine builders and there are engine assemblers." Engine builders think beyond the surface. Good engine builders examine every detail, especially the stuff most of us never see. Here are a few examples.
Cylinder-wall boring and honing is a science unto itself. Doing it well takes an understan
Water-pump passages, not to mention oiling-system passages, should be worked smooth to red
Safety wire is a racing thing as well as an aviation thing because you can't just pull off
MSD is the choice of better racers everywhere. Blair chose MSD to light his fire. Marvin d
This is a racing power-steering pump designed for high-rpm use. Blair brought it to Marvin
"Trust-but verify..." Marvin tells us. Here, MCE Engines has written detailed information
Lubricate And Secure
When Marvin was building Blair's 427W, he gave us a crash course in thread lubrication and security. We want bolts to remain secure, and we want them to glide smoothly into place to achieve accurate torque readings. Never install and torque fasteners while dry. Always lubricate threads. When you are using a thread locker such as Loctite, the thread locker acts as a lubricant during tightening. Then, it cures and secures.
Loctite 7649 primer prepares surfaces for thread lockers. Loctite 271 is high-strength, go
These custom long-tube, 300-series stainless steel headers were fabricated by Butler & Son
Marvin (left) and Blair watch and listen closely during the 427's initial run-up. These ge
How Much Grunt
Marvin used Desktop Dyno PC simulation software for a look at how much power Blair's 427W should make:
|RPM ||HP ||Torque |
|2,000 ||188 ||495 |
|2,500 ||254 ||533 |
|3,000 ||320 ||560 |
|3,500 ||396 ||593 |
|4,000 ||470 ||617 |
|4,500 ||534 ||622 |
|5,000 ||576 ||605 |
|5,500 ||590 ||563 |
|6,000 ||601 ||523 |
|6,500 ||577 ||466 |