Building Power & Durability: Veteran engine builder, Marvin McAfee, builds a 598ci Ford T-Rex for street and strip

Photography by the author, Jim Smart

Sometimes, it’s just okay when you’re in your seventies to take a crack at something you’ve always wanted to do. Marvin McAfee of MCE Engines in Los Angeles, California always wanted to build a 1000-horse Ford big-block, but understood he couldn’t do it with a stock block and heads. He also understood durability becomes dicier when you’re building more and more power into an engine. He needed more robust iron, steel, and aluminum to get the job done. Back in the day, Marvin was a crew chief in SCCA/Trans-Am competition against great racing legends like Parnelli Jones, George Follmer, Jerry Titus, Carroll Shelby, Dan Gurney, and a host of other notables. When Marvin retired, he wanted one last big hurrah before settling into Social Security and basking in a lifetime of memories.

Marvin knew he couldn’t achieve 598ci and 1000 horsepower with a stock 460 block even at its very best. At best—he knew he could get 700 horsepower with a stock block and that would be pushing the imagination if for no other reason than durability. A stock block would likely never be able to survive the continuous hammering of 700+ horsepower. He looked to Ford Racing for the A460 race block for his foundation. His objective was durability and displacement. The most he could get into a stock 460 block was 557ci. What’s more, he would never be able to get solid durability from a stock block with a 1000-horse game plan.

With the M-6010-A460 block, Marvin was able to open up the bores to 4.600-inches, with more stroke at 4.500-inches. The A460 block offers an 18-bolt deck instead of the normal factory 10-bolt decks for added security. This bolt pattern calls for a different cylinder head, intake, and exhaust gaskets because this isn’t a stock 385-series mill. The Ford Racing A460 utilizes a 10.322-inch deck height (plus or minus 0.005-inch), and has a suggested retail price of $2,995 (price subject to change). Not bad for just under three grand.

Marvin set a realistic target of 800-900 horsepower and 700 lb-ft of torque though he was in hot pursuit of ultimately getting 1,000 horsepower from this engine with dyno time and upgrades. He kept his expectations realistic—with a power band spanning 2,500-7,000 rpm. He looked to Eagle Specialty Products and Mahle Pistons for the displacement he wanted. The decision to go with Eagle and Mahle came after consulting with a number of stroker kit manufacturers to determine the best choice. Marvin looked at the numbers, electing to go with an Eagle 4340 steel crankshaft with 3.000-inch mains and 2.200-inch rod journals.

The Eagle rods are 6.800-inch 4340 H-beam forgings center to center (PN CRS68003D2000). Mahle’s best coated and forged flattop pistons were selected, with a wristpin location designed for the 460-inch Ford. They’re off-the-shelf pieces you can get by filling out an Eagle Specialties order sheet and selecting PN 99-8402-1.

When Marvin originally planned this project, his goal was a broad torque curve—with the focus being brute torque for street and strip. The more Marvin thought about his 598 project, horsepower became more important if you were going drag racing. This really is a drag racing engine by design. He opted for a mechanical roller camshaft from Comp Cams, PN 34-850-9. The selected cam features an rpm range of 4,400 to 7,200 rpm with 112-degree lobe centers. Valve lift is 0.727-inch both the intake and exhaust, with duration measuring in at 275/281 degrees at 0.050-inch.

Because Marvin is methodical about his blueprinting, he covers all the bases. He stresses the importance of doing a mock-up any time you build an engine whether it’s a stocker or a racing engine. When you’re building a stroker, and especially with an aftermarket block, it is important to do a mock-up because cranks, rods and pistons don’t always clear the block. You don’t want to find this out when it’s time to assemble the engine. We’ve encountered numerous examples of why this is important—and connecting rod bolts hit cylinder skirts or a crankshaft counterweight tags a piston.

Ford A460 Block Facts

M-6010-A460 Ford Performance 460 Siamese Bore Wet Sump Cylinder Block

High-strength block excellent for professional competition
10.322-inch deck Height plus or minus .005-inch
Cast iron block with Four-Bolt #2, 3 and 4 main caps
Nodular iron main caps
3.000-inch main journal diameter
Siamese cylinder bore design
Can be bored/stroked to 598ci
Bore range from 4.360-4.600-inches – Is also available in big bore version, part number: M-6010-A460BB
Wet sump oiling design
Improved priority main oiling system design
Weighs approximately 275 lbs.

NOTE: Siamese blocks are solid casting between the cylinder bores. There are no water passages between them. This is done to increase block strength. Four bolt main caps requires stock oil pan modifications at #2, 3 and 4 main caps.

Head Trip

Because Marvin has a lot of drag racing experience, he looked to Ford Racing for proven M-6049-C460 Sportsman cylinder heads along with the race-rugged Jesel valvetrain. Because Marvin’s using M-6049-C460 heads and Ford F3ZM-9424-C460 single-plane induction, we’ve got to go with a special Ford Racing intake manifold gasket. You will need the M-9439-G460 intake manifold gasket set from Ford Racing.

Here are the high points of the C460 head.

For use with M-6010-A460 Ford Performance cylinder block
Used for professional competition and serious “Sportsman” racers
Made from 356-T6 aluminum, with bronze valve guides and a premium valve seat insert material compatible with titanium valves
Valve angles are 7.5 degrees intake, 8.0 degrees exhaust with no side cant
Raised intake and exhaust ports
65cc wedge-style combustion chamber
4.600″ recommended bore size (4.500″ minimum)
2.450″ intake, 1.900″ exhaust recommended diameters
Port and combustion chamber design based on Ford Performance 351 “Yates” cylinder head

PowerHeads of Wildomar, California, cleaned these C460 castings up with a port match for improved flow. Seat pressure (valves closed) was 228 pounds at 1.900-inches installed height. Open pressure was 702 pounds at 1.200-inches, with spring coil-bind at 1.090-inches. Our C460 cylinder heads with a PowerHeads port job and valve job flowed 380 cfm at 0.700-inch lift on the intake side, and 225 cfm at the same lift on the exhaust. This made a great set of heads even better.

Marvin’s goal was 800-900 horsepower. He knew a stock 460 block wasn’t going to get him there without failure. Marvin looked to Ford Racing for answers he found in the A460 block. The A460 block is virtually unlimited in the amount of power it can handle with siamesed cylinder bores, thick main webs, and four-bolt mains with steel main caps. It will take up to 2,000 horsepower.

Down under, the A460’s thick four-bolt main webs are capable of brute horsepower, which makes this guy quite safe for someone aiming for 1,000 horsepower.

Dynamic balancing is critical to durability because vibration is destructive. Larry Revis of Revco Precision Balancing has this task down to a science. Marvin likes his dynamic balancing to be within one-tenth of a gram. Dynamic balancing begins with weighing each reciprocating part and getting each of these parts to weigh exactly the same as the lightest part.

To get the displacement and durability Marvin wanted, he looked to Eagle Specialty Products for the 4340 steel crank, H-beam rods, and Mahle forged and coated flattop pistons.

Crankshaft endplay is checked next. Acceptable endplay is .004-.008-inch.

Marvin stresses the importance of a pre-assembly mock-up where you check the fit of all components. This is labor-intensive step, but critical to proper assembly. Crank, pistons and rods are installed (without piston rings). The rotating assembly is turned slowly to check crank counterweight-to-block and piston skirt clearances. You also want to check rod-bolt-to-block clearances.

Crankshaft runout is checked in the block as shown. Journal and bearing clearances must also be checked.

Marvin whips up his own engine assembly lube formula for his engine builds under the assumption the engine could sit in storage for a while. Piston skirts and rings get a generous coating along with main, rod and cam bearings.

Piston ring end gaps have been checked, with gaps properly spaced 45-degrees apart.

This is where bore and stroke come together to make horsepower and torque. The Eagle/Mahle kit yields a 4.600-inch bore with a 4.500-inch stroke, which is nearly square.

True top-dead-center must always be checked with a dial indicator (not shown here) before the cam is degreed in. We were not present when Marvin checked both.

Before you is a bulletproof package capable of making 2,000 horsepower. Marvin is play it very conservative at 800-900 horsepower for durability for a terrific street and strip big-block for a classic Ford or late-model Fox Mustang. If we could have done anything differently we would have opted for ARP studs and rod bolts.

Marvin has his own system of torquing fasteners. He generously lubes bolt threads with 30-weight engine oil and hand snugs the fasteners, then, torques them in one-third values to total. He goes back and checks every fastener. When you’re using studs, Marvin suggests running the studs down, but never bottoming them out. Here, Marvin checks each main cap for proper resistance to rotational resistance.

Camshaft endplay is checked much as Marvin does with the crank. Endplay should be .003-.006-inch.

Marvin considered stud-mounted rocker arms and guide plates. Most engine failures happen due to valvetrain failure. That’s when Marvin ordered a complete fully-adjustable shaft-mounted rocker arm system from Jesel. When Marvin contacted Jesel, they came up with their best Mohawk Beam Pro Series shaft assembly ( PN KPS-11057). At just 195 grams each, this is Jesel’s stiffest lightest rocker arm with the lowest moment of inertia.

With this big mechanical roller from Comp Cams, Marvin believes peak torque should roll in around 5000 rpm, with horsepower topping out around 6500 rpm. Keeping with the same lobe centers (112) as the original cam he had planned, Marvin has chosen to increase both lift and duration to maximize breathing efficiency at high rpm.

Marvin blueprints every component, including valve springs, keepers and retainers. He massages away the rough edges to reduce any wear potential. He also coats the springs and related parts with his own assembly lube, which reduces frictional issues during initial fire up and break-in.

Valve spring pressure and installed height are handled at this time during cylinder head assembly. Marvin has done his own multi angle valve job along with the installation of Ferrea stainless valves. Ferrea manufactures hardcore racing engine valves and components for various types of engines. Installed height is 1.900-inch using one of Marvin’s own go/no-go gauges.

Marvin has wrapped up the short-block and is ready to tackle final assembly. This is a nice piece, and these are approaches you can apply to your Ford 385-Series big-block.

Marvin coats all internal iron and aluminum surfaces with GE Glyptol, which seals the cast surfaces and improves oil return flow. The screen keeps any stray debris out of the oil pan where it could become lodged in the pick-up and oil pump.

Marvin laughs when he thinks of how many times he’s seen builders forget to install rear block plugs, which is easy to overlook. Use Permatex’s The Right Stuff on the cam plug. Teflon tape or sealer on all screw-in block plugs gets the job done.

We’re opting for Fel-Pro gaskets throughout this engine. Deck surfaces must be wiped down with a tack cloth and checked for irregularities before the gaskets and heads go on. The Right Stuff is applied lightly around cooling passages and at the intake manifold. Marvin has studded the heads for exceptional security.

Marvin wipes down head deck surfaces to remove any debris, then, checks surfaces with his fingertips to feel for any debris.

These Ford Racing Sportsman heads yield Holland Tunnel-sized intake ports and compact chambers with great quench. These heads sport 18-bolts versus 10 on a stock block.

Valve lash is set by turning the crankshaft in 90-degree increments with the engine’s firing order. Marvin has marked the balancer at TDC/ZERO, 90-degrees, 180-degrees, and 270 degree increments. Marvin does initial valve adjustment cold, allowing for .004-inch growth from thermal expansion as the engine gets hot. Intake valve lash is .024-inch cold or .028-inch hot. Exhaust is .026-inch cold and .030-inch hot.

Marvin’s routine includes oil pump blueprinting, which includes checking clearances and the relief valve for freedom of movement and proper function. Bolts are safety-wired as an added measure of security. Because the T-Rex was being built for a Fox Mustang platform, it gets the double-sump Milodon pan.

The only intake to go with was this single-plane Ford Racing high-riser designed specifically for the Dominator.

Marvin opted for the Holley Dominator 1150cfm carburetor with the only modification being optional jet extenders. Jet extenders keep fuel around the jets in drag racing and hard acceleration. Jet sizing was determined during this engine’s first jet check during the dyno pull. This is the one-inch Wilson CNC carburetor spacer (PN 024110) engineered to improve velocity, which increases horsepower and torque.

Dampening crank twist and vibration is the ATI Super Damper.

The only choice for the T-Rex is an MSD ignition package from Summit Racing Equipment. Marvin has blueprinted and curved the MSD billet distributor.

The Interrogation Room

When we go to the dyno room, there’s always great apprehension and hope. Fear we will blow the darned thing up. Additional fear we won’t make our numbers. For Marvin, who was understandably nervous, there were challenges. We conducted three pulls and left with mixed feelings about our numbers. We needed more dyno time—at least two or three days of extensive testing and tuning. We didn’t have the luxury of time. What’s more, we would never be back to the dyno with this engine. Marvin’s eyesight began to deteriorate along with his health, which would have made another dyno session impossible. Marvin is in poor health these days and is no longer building engines.

Because the C460 head isn’t a widely produced cylinder head, finding just the right headers was virtually impossible. No one had them on the shelf. We reached out to Custom Performance Racing in Gardena, California for help. They knew exactly what we needed to make the most of Marvin’s big-block. Marvin wanted custom equal length step headers with 2 1/8-inch primary tubes segueing into 2 ¼-inch pipes down to 4.5-inches. Custom Performance had to go with a 4.0-inch collector because necessary raw materials (4.5-inch pipe) weren’t in stock. Still—numbers exceeded Marvin’s expectations and put 1,000 horsepower within reach.

Pull 1

Holley 1,150-cfm Dominator
(PN 0-80673)
Jetting: 0.90/0.90
Ignition Timing: 32 Degrees BTDC at 3,500 rpm
A step pull in 500-rpm increments beginning at 4,000 rpm

RPM	HP	TQ
4,000	567.1	744.6
4,500	672.7	785.1
5,000	764.1	802.6
5,500	821.4	784.4
6,000	859.7	752.5
6,500	895.4	723.5

Marvin started with 0.90 jets in the primaries and secondaries, which weren’t enough causing a lean condition. Based on air/fuel ratio and brake specific fuel consumption (BSFC) numbers, we stepped up to 0.92 jets in the primaries. Ignition timing was conservative at 32 degrees BTDC in the interest of durability.

Pull 2

Jet Change/Primaries

Jetting: 0.92/0.90
Ignition Timing: 32 Degrees BTDC at 3,500 rpm

RPM	HP	TQ
4,000	503.9	661.6
4,500	690.4	805.8
5,000	784.1	823.6
5,500	838.3	800.5
6,000	878.9	769.3
6,500	909.8	735.1

Marvin increased primary jet sizing one step at a time again as a measure of fine-tuning. The 0.92 primary jets did add 14.4 horsepower and 21.0 lb-ft of torque. Marvin went up a jet size in the secondaries to 0.93.

Pull 3

Jet Change/Secondaries

Jetting: 0.92/0.93
Ignition Timing: 32 Degrees BTDC at 3,500 rpm

RPM	HP	TQ
4,000	521.5	684.5
4,500	698.1	814.8
5,000	787.4	827.1
5,500	848.1	809.9
6,000	883.4	773.3
6,500	915.7	739.9

Marvin’s 598ci T-Rex produced 915.7 hp and 827.1 lb-ft of torque. We are thrilled these numbers surpass Marvin’s expectations. However, we’re convinced that with more dyno time, this engine would be courting the 1,000 horsepower mark. Marvin became decidedly frustrated with fuel line sizing, which adversely affected our numbers. We needed a larger 7/16-inch fuel line to get the air/fuel mixture where it needed to be to get 1000 horsepower.

SOURCES:

Comp Cams

800/999-0853

901/795-2400

www.compcams.com

Custom Performance Racing

310/427-7486

www.cprengines.com

Ford Racing Performance Parts

800/FORD788

www.performance.ford.com

Holley Performance Products