In every engine builder's life, there comes a moment when it's time to prove something to themselves and to others. This is one such moment for veteran engine builder Marvin McAfee. He's out to prove how much power can be made with the 385-series Ford big-block, while dialing in an appropriate amount of durability.
McAfee has been building engines for more than 50 years. He's an FAA-certified airframe and powerplant technician with abundant gas turbine and radial piston engine experience. He was also a crew chief in SCCA/Trans-Am competition, competing against great racing legends we're all familiar with-Parnelli Jones, George Follmer, Jerry Titus, Carroll Shelby, Dan Gurney, and a host of other history-making notables.
The Ford Racing M-6010-A460...
The Ford Racing M-6010-A460 block is a brute cast-iron Siamese-bore competition block you can use for street or strip.
When McAfee began planning to build this 598ci Ford big-block, he intended to go with a stock 460 truck block with standard bores, or perhaps the Ford Racing Super Cobra Jet block. However, he wouldn't have been able to pump 598 ci into a stock block. At the time, we knew that a new 385-series competition block was coming from Ford Racing Performance Parts, and when Ford Racing called us with exciting information about the new competition M-6010-A460 block, McAfee suggested they have Yellow drop one off at his Los Angeles shop.
While the 385-series 460 was factory rated at 365 hp, it could only be opened up so much with regard to displacement. With the M-6010-A460 block, McAfee would be able to take out the bore to a whopping 4.600-inches, and the stroke could be lengthened to 4.500-inches. The A460 block yields an 18-bolt deck on each side instead of the normal factory 10-bolt decks. This means different head, intake, and exhaust gaskets because this isn't an ordinary 385-series engine. The new A460 utilizes a 10.322-inch deck height (plus or minus 0.005-inch), and has a suggested retail price of $2,295.
It is a four-bolt-main block...
It is a four-bolt-main block with dowel-pin centered nodular iron main caps on mains 2, 3, and 4 for extraordinary strength. This A460 uses a wet sump oiling design, along with 3.000-inch main journals, and tips the scales at 290 pounds.
To keep costs down, McAfee planned to use off the shelf parts that would enable him to break through the traditional horsepower ceiling, along with appropriate spine decalcifying torque numbers. He set a target of 800 hp and 700 lb-ft of torque. To achieve these goals, McAfee expected the powerband to span 2,500 rpm, with a redline of no more than 7,000 rpm.
McAfee looked to Eagle Specialty Products and Mahle Pistons for the enormous displacement he wanted for the T-Rex project. The decision to go with Eagle and Mahle came after consulting with a number of stroker kit manufacturers to determine the best pick. McAfee examined the numbers, electing to go with an Eagle 4340 steel crankshaft that uses 3-inch mains and 2.20-inch rod journals.
The connecting rods are 4340 forged H-beam pieces that measure 6.80 inches from center to center (PN CRS68003D2000). Mahle's best forged pistons were chosen, which started life as a big-block Chevy design with a wristpin location adjustment to make them work with the 460 Ford. This makes them off the shelf pieces you can easily get by filling out an order sheet (PN 99-8402-1). This is the first time Mahle has ever made this particular piston for a 385-series Ford big-block.
We like the A460's four-bolt...
We like the A460's four-bolt main caps, which are actually an interference (pinch) fit for added strength and rigidity.
When we started talking with McAfee about this project back in 2005, his goal was maximum torque rather than horsepower. Thus he ordered a specific mechanical roller camshaft. 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. With that, he had a change of heart with camshaft selection, opting instead for a different mechanical roller camshaft from Comp Cams (PN 34-850-9).
The bumpstick features an optimum rpm range of 4,400 to 7,200 rpm, and uses 112-degree lobe centers. Valve lift checks in at 0.727-inch for both the intake and exhaust valves, and the duration measures 275/281 degrees at 0.050-inch.
Engine builder Marvin McAfee...
Engine builder Marvin McAfee had to use a puller to remove these main caps during mock-up phase.
With these specifications, peak torque should happen somewhere around 5,000 rpm, handing off to peak horsepower around 6,500 rpm. While retaining the same lobe centers (112), Marvin has chosen to increase both lift and duration to maximize breathing efficiency at high rpm. It is important to remember horsepower is a product of not only torque, but also rpm. When we increase lift and duration, we enable the engine to ingest a bigger intake charge at high rpm.
McAfee considered stud-mounted rocker arms and guideplates in the original build plan, but after talking with the techs at Jesel Valvetrain, he ordered a complete shaft-mounted rocker arm system. Jesel came up with its best top-of-the-line Mohawk Beam Pro Series shaft assembly (PN KPS-11057). At 195 grams each, this is Jesel's stiffest, lightest rocker arm with the lowest moment of inertia while producing precise valve control with minimum frictional losses.
So these are the basics that will provide the foundation for this 800-plus-hp monster mash engine build. Next month, we'll bring you the induction system and assembly, which will be followed by a third and final installment where we flog it on the dyno for all it's worth.
In addition to using four...
In addition to using four fasteners, Ford Racing installed dowel pins to make sure the main caps don't move.
We like this 4340 forged steel...
We like this 4340 forged steel crank from Eagle Specialty Products with its 3.00-inch main and 2.20-inch polished rod journals with chamfered oil holes for improved lubrication.
Eagle Specialty Products works...
Eagle Specialty Products works closely with Mahle on most of its stroker kits, and our 598 is no exception. Because McAfee is maximizing power, he opted for low-friction rings that are narrower than most of us are used to. This ring package is 1.5mm, 1.5mm, and 3.0mm for reduced friction. A support rail keeps the oil ring package stable. Turning thermal energy into rotary motion is a 6.80-inch center-to-center 4340 H-beam rod with ARP cap screws.
Here is the custom-forged...
Here is the custom-forged Mahle piston with a 15cc dish designed for the 598ci stroker kit. The dish includes valve reliefs designed to clear our huge M-6049-C460 valves. In its most basic form, this is a big-block Chevy piston, but Mahle has relocated the wristpin for our big-block Ford. This is how you get nearly 600 ci from a 385-series Ford.
For this application, we will...
For this application, we will be using an ATI Super Damper (PN SUM-B64272).
Dynamic balancing begins with...
Dynamic balancing begins with weighing each reciprocating part and getting each of these parts to weigh exactly the same as the lightest part. For example, we find the lightest piston. We then remove weight from seven corresponding pistons in a precision weight loss program. Next, the same thing happens with the connecting rods.
McAfee has been working with...
McAfee has been working with Larry Revis of Revco Precision Balancing for many years. McAfee likes to get his balancing to within one-tenth of a gram for unequaled smoothness.
Once all reciprocating mass...
Once all reciprocating mass has been balanced, Revis sets up bob weights, which will be hung on the crankshaft journals as simulated reciprocating mass (weight). These bob weights should weigh the same as reciprocating mass.
Revis spins the 4340 Eagle...
Revis spins the 4340 Eagle crankshaft just like we'd spin a wheel and tire on a balancer. Dynamic balancing finds the out of balance areas where weight will have to be removed or added to get things in perfect balance.
The crankshaft counterweight...
The crankshaft counterweight has to be drilled to remove excess weight. As a seasoned balancer, Revis knows how much steel has to be removed. It could have easily gone the other way where Mallory metal would have to be added to get it in balance.
Because this particular engine...
Because this particular engine is internally balanced, both flywheel and harmonic damper are balanced independently of the crankshaft. Revis balances McAfee's McLeod steel flywheel (PN 463220, 176-tooth) on the crankshaft for convenience and consistency mostly. However, it is not balanced with the crankshaft.
Metal is removed from the...
Metal is removed from the flywheel to get it in balance. Because this is an internally balanced engine, the flywheel is zero balance to begin with.
Because we're working with...
Because we're working with an ATI Super Damper, the balancer can't be dynamic balanced, however, its hub can. Here, Revis drills out excess weight from the hub.
The A460 block doesn't use...
The A460 block doesn't use a conventional Fel-Pro FPP-1018 385-series cylinder head gasket (top) for a number of reasons. The A460 block calls for a Fel-Pro #1092 18-bolt steel core laminate head gasket (bottom) with 4.700-inch bores. Gasket compression volume is 14.6 cc's at a 0.051-inch crush.
Surprisingly, the bolthole...
Surprisingly, the bolthole size was too small for this application. McAfee simply punched them out to the needed 9/16-inch.
McAfee always performs mock-ups...
McAfee always performs mock-ups as part of his engine building regimen, even if he's building a stocker. The mock-up phase allows you the opportunity to find all potential problems, regardless of how minor they might be, before final assembly. During mock-up phase, McAfee checks the Eagle crankshaft for an endplay measurement of 0.004- to 0.008-inch.
Here, McAfee checks the Eagle...
Here, McAfee checks the Eagle crankshaft for full-indicated runout, which tells us how straight the crankshaft is. Maximum allowable full-indicated runout is 0.001-inch. Runout beyond 0.001-inch puts the oil wedge at risk at the bearing and journal.
McAfee opted for a mechanical...
McAfee opted for a mechanical roller camshaft from Comp Cams (PN 34-850-9). This 112-degree lobe center bumpstick features a duration of 275/281 at 0.050-inch, and a valve lift of 0.727-inch on both the intake and exhaust valves.
McAfee has been using ASL's...
McAfee has been using ASL's CamGuard in all of his engine builds, including this T-Rex build. It's a supplemental additive package to be used with every oil and filter change to increase engine life and fuel economy. You can get CamGuard from MCE Engines by the bottle or by the case.
To complement our aggressive...
To complement our aggressive mechanical roller camshaft, McAfee ordered a complete shaft-mounted rocker arm system from Jesel. After hearing about the engine's specifications, Jesel came up with its top-of-the-line Mohawk Beam Pro Series shaft assembly (PN KPS-11057). At 195 grams each, this is Jesel's stiffest, lightest rocker arm with the lowest moment of inertia while producing precise valve control with minimum frictional losses.
Ford Racing's induction system...
Ford Racing's induction system for the big-block Ford features a huge single-plane high-rise manifold designed for a Holley Dominator carburetor. Aside from port matching, McAfee chose to leave the manifold as is right out of the box, as he believes that the rougher cast surfaces keep more fuel droplets in suspension for better distribution.
Because we're using M-6049-C460...
Because we're using M-6049-C460 heads and F3ZM-9424-C460 induction, a special intake manifold gasket (M-9439-G460) is required and available from Ford Racing Performance Parts.
The Holley Dominator 1150...
The Holley Dominator 1150 (PN 0-80673) carburetor was used right out of the box, except for the installation of jet extenders. Jet extenders keep fuel around the jets in drag racing and hard acceleration. Jet sizing will be determined during this engine's first jet check at the dyno. Marvin has also opted for a Holley mechanical fuel pump (PN 12-460-11, 110 gph) to feed this hungry atomizer. The 1-inch Wilson CNC carburetor spacer (PN 024110) is designed to increase velocity, resulting in horsepower and torque increases. Next month, we'll be back with the assembly of this monster engine.