598ci Big-Block Engine Build, Part 2
Last month, we introduced you to the 598ci T-Rex Ford 385-series big-block from MCE Engines in Los Angeles, California. In truth, we're cheating a little bitbecause it's unfair to call this engine a 385-series 460 Ford big-block. The A460 block is an all-out, super-cube drag racing big-block from Ford Racing Performance Parts. It's not your father's 460 from that old stodgy Lincoln Continental freeway battlewagon. For one thing, you could never infuse 598 ci into a stock 460 block because the stock bore and deck numbers aren't there. This is where the new Ford Racing A460 block comes in to play with its thick webs and decks, siamesed 4.600-inch bores, and 10.322-inch deck.
When Marvin McAfee of MCE Engines began planning the T-Rex 598, his goal was to shoehorn as much displacement as he could into this Ford behemoth, while keeping with durability. His logic was pure common sense street smarts-what good is more than 1,000 horsepower if the darned thing blows up? He came up with a near square combination-a 4.600-inch bore and 4.500-inch stroke to achieve 598 ci. Eagle Specialty Products and Mahle Motorsports came up with terrific off-the-shelf components for this effort, and durability comes from making all of your power at the lowest rpm range possible. In other words, Marvin wanted this thing all finished at 6,800 rpm, with peak torque happening between 4,500 and 5,000 rpm, and a redline of 7,200 rpm.
McAfee's great success comes from more than a half century of engine building experience. At 77, he knows what works and what doesn't. His success starts with a methodical technique, along with selection of the right parts. Lets get started.
McAfee stresses few things...
McAfee stresses few things are more defeating than a leaker. His strategy is to stagger rear main seal end gaps away from the main cap parting lines. He also uses a thin film of sealer between the seal and main saddle for added assurance. Additionally, he also reminds us to make sure each seal is positioned correctly with lips facing inside. Get this backwards and you can count on having oil on the floor.
Supporting such a huge arm...
Supporting such a huge arm and crank are Clevite 77 main (PN MS-1039V) and rod (PN CB-743VND) bearings, which offer increased durability and improved crush for severe duty operation. McAfee has installed restrictors between the main and cam journals in No. 2 through No. 5 main saddles to reduce flow to the cam bearings and improve main bearing lubrication.
McAfee coated the bearings...
McAfee coated the bearings and journals with his own special assembly lube mix that yields staying power, should an engine wind up sitting for an extended period of time prior to firing up. This is an Eagle 4340 steel crank (PN 44604450002200EGAR100) with 4.500-inch stroke, 3.000-inch mains, and 2.200-inch rod journals, and it weighs roughly 85 pounds. It sports a huge arm (read-huge mechanical advantage), in fact it's the most stroke we've ever rolled into a Ford big-block here at Modified Mustangs & Fords.
Huge 3.000-inch mains sit...
Huge 3.000-inch mains sit on race-ready Clevite 77 bearings. McAfee blueprints each and every bearing for perfect crush and a solid oil wedge. Bearings are installed bone dry, then lubricated between the journal and bearing only to ensure a good wedge on start up...
...Once McAfee sets the crank,...
...Once McAfee sets the crank, he checks bearings for solid seating, double-checking his installation work. He gently rolls the crankshaft over and checks feel. Ideally, it should turn with one hand on the snout both before main caps go on and after.
Before the main caps are torqued,...
Before the main caps are torqued, the No. 3 thrust bearing must be centered. McAfee gives each end of the crank a whack with a dead blow mallet (though a brass hammer is being used here), which centers the thrust faces. This ensures uniform journal fit.
Choosing The Right Cam For the Job
When we started talking with McAfee about this project back in 2005, his goal was maximum torque rather than horsepower. He ordered a mechanical roller camshaft bent more on torque than horsepower. As time passed and we waited for the A460 block, McAfee started thinking about why horsepower was more important to this project than torque. Torque is a byproduct to an engine this size. Torque is there no matter what you do with horsepower. Earthmoving torque.
McAfee had a change of heart with camshaft selection, opting instead for the 34-850-9 mechanical roller camshaft from Comp Cams. Here's how this bumpstick adds up:
- RPM Range: 4,400 to 7,200 rpm
- Lobe Centers: 112 Degrees
- Lobe Lift Intake/Exhaust: 0.421/0.420-inch
- Valve Lift Intake/Exhaust: 0.727/0.727-inch
- Duration at 0.050-inch: 275/281
- Duration at 0.020-inch: 308/316
Additional components for the build
- Lifter Set: 836-16
- Push Rods: Manley #1610-16 (3/8-inch w/0.080-inch wall)
- Timing Set: 3122
- Valvesprings: 998-16
- Retainers: 733-16
- Keepers: 611-16
- Lash Caps: 621-16
With this mechanical roller from Comp Cams, peak torque should be somewhere around 4,500-5,000 rpm, handing off to peak horsepower around 6,500-6,800 rpm. Redline, per MCE Engines, is 7,200 rpm. Valve float is likely beyond 7,200 rpm.
While retaining the same lobe centers (112), McAfee chose to increase both lift and duration to maximize breathing efficiency at high rpm. It is important to remember that horsepower is a product of not only torque, but rpm. When we increase lift and duration, we enable the engine to ingest a bigger intake charge at high rpm.