Modular Roll

Ford's Modular engine has come a long way since the underpowered version used in the '96 Mustang GT. Today, the GT makes an honest 260 hp, but if that's not enough you can opt for the 305hp DOHC Mach 1 or the mighty, supercharged Cobra the pumps out 390 ponies and an equal amount of torque. Of course, those are the factory horsepower numbers. As you would expect, racers and street enthusiasts have pushed the 2V and 4V variants way past the original design limitations using raised compression, nitrous and boost. Amazingly, some are reaching upwards of 600-800 hp and doing so using many stock parts. And while some guys (and gals) have gone very, very fast, others have found a problem with the valve springs and rockers.

Quite simply, they are failing. Broken springs and tossed rockers (also called camshaft finger followers) sometimes fly off. The question is why?

In a high-performance pushrod v-8 (302, 351 or other) we often change the cam, lifters and rockers to match our big cylinder heads and aftermarket intake. We know big cams and/or high rpm operation requires improved valvetrain components that are more stable and stronger than stock. And we also know there are dozens of manufacturers making roller rockers, lifters and pushrods for the 302, 351 and all the big-block pushrod engines. But unfortunately the Mod crowd has been stuck with the factory steel finger followers and tiny hydraulic lifters ---until now.

Enter Second Street Speed (Perkasie, Pennsylvania), a leader in EFI, late-model performance and techn9ology, and engine building. Lon Moyer and

Bill Hunsberger of Second Street were two of the first guys to equip their shop with a dynojet, and they also have a Superflow SF-1020 flowbench and a superflow 901 engine dynometer in their arsenal. To their credit, they've assembled a variety of hot 8-,9-and 10-second street/strip cars, a top- running EFI small-block that runs in NHRA Competition Eliminator, and the 400-inch nitrous monster in Jeff Allebach's NMRA Pro 5.0 entry.

Recently though, Moyer and Hunsberger have been extensively exploring the depths of Ford’s 4.6 modular engine and they’ve collectively solved the rocker arm problem.

“We’ve found that most high-horsepower or high-rpm Modular engines had issues with rockers and springs that cause them to fail. And we’ve found that there are two scenarios that may cause this,” said Moyer in the backroom of his shop. “at 8,000-9,000 rpm, the modular engines make a lot of oil pressure and this can cause the lifters to pump up. Essentially making them solid. When the lifters pump up, something has to give and the valves hang open. Valvetrain control is lost and the valve float head,” he explained. “The other theory is the oil becomes aerated at high pressures, which causes the oil pressure to drop. And with the oil pressure reduced, the lifters can no longer hold the rockers against the cam and they fall out of place.” He added. However, the first scenario is far more likely to occur.

Second Street first tried solving the problem by bumping the valve spring pressure to compensate for the “pumped up” lifters, but according to Moyer, “You can’t simply up the spring pressure. Closed pressure on the stock springs is only 65 pounds and we’ve found that you can only go to about 80 pounds before the lifters collapse.” Moyer then tried making solid lifters by filling the guts of stock lifters. This worked fairly well, but he couldn’t keep the new lifter internals from failing, so it was back to the drawing board.

The end result is a totally new design incorporating adjustable roller rockers and solid lifters, and the performance is astonishing. The new rockers are made from aluminum (the stock rockers are steel) and feature a large center roller, which the cam rides on, along with a second roller on the rocker tip, which contacts the valve. This smaller roller incorporates unique side rails that contain the valve tips and prevents them from sliding off. The opposite end of the rockers has a ball to capture the lifter and an adjuster to set valve lash.

The valvetrain system in the modular engine is known in the industry as a CORA (cam on rocker assembly) and the stock rockers are stated to have a 1.8:1 rocker ratio. However, as Moyer explained, “With this valvetrain design the rocker ratio changes with motion because the rockers don’t have a fixed pivot point. Actually, the pivot point changes as the rockers run through the arch of the valve motion. Valve lift is greatly affected by lobe design and, therefore, the stock rockers do not have a true 1.8:1 ratio, as would be typically measured in a pushrod engine.

Moyer went on to explain because of design limitations (mainly due to clearance between the adjusters and cam lobes), the pivot points on the SSS rockers are slightly different than stock. His rockers offer more duration, but slightly less lift. “We had to design the rockers to physically fit in the engine. Clearance is tight between the adjusters and the cam lobes, so making it all fit took a lot of work. Nevertheless, understand because of the solid lifters, our valvetrain will ultimately give the engine greater valve lift at high rpm due to the fact there’s far less deflection in the valvetrain.” Moyer also explained his setup will work with stock or aftermarket springs, and re-ground stock cams or aftermarket ones. And since the rockers and lifters are the same in all SOHC and DOHC engines, the SSS valvetrain will work in any Modular engine.

Testing was completed on a ’99 Cobra engine that was rebuilt with ported heads and intake. Oliver rods and Ross pistons (8.9:1) designed for big boost. The factory .393-inch lift cams were replaced with hotter .486-inch lift cams that also have a bit more duration. Additionally, the engine is equipped with a Paxton blower, but the unit was left disconnected during testing so the results would be closer to what owners might see on a stock or mildly modified engine.

To get the test going the engine was run on the Superflow 901 with the stock valvetrain. Moyer ran quite a few tests and most of the pulls were made between 4,000 and 7,000 rpm. The engine made just over 360 horsepower all through the 6,200-6,400 rpm range. Torque was in the 340 range between 4,400-5,100 rpm. The best numbers we observed were 366.8 hp at 6,300 rpm and 345.9 lb-ft of torque at 5,000 rpm.

Moyer and Hunsberger then removed the cam covers and installed the roller rockers and solid lifters. Lash was set to .003-inch for the intake and the exhaust. Moyer used a feeler gauge and made the adjustment with the gauge between the cam lobe and roller, not between the valve tip and roller, as is conventionally done with a pushrod engine. The reason is because the rails on the roller spool (for the valve) are too narrow to fit a feeler gauge. Moyer says that .003-inch lash between the cam and roller actually equals .007-.008 at the valve tip.

The Cobra engine was buttoned up and tested again, with almost unbelievable results. Power was immediately, jumping to the 390 range between 6,000-6,2000 rpm, and with the torque following suit with a bump up to the 370s between 4,800-5,100 rpm. Peak horsepower was now 392 at 6,200 rpm and peak torque was 375 at 5,100 rpm. At the highest point we observed a gain of 40 lb-ft of torque at 5,800 rpm.

“I figured the engine would pick up about 10 hp and I would have been elated with that,” says Moyer, who was really just looking for more reliability. “But it picked up over 40 hp at the top of the range.”

Like we said, the gains in power are almost too good to be true, but the before and after dyno testing proved otherwise. We learned that anything can happen when it comes to valvetrains, especially when you design and install something that is better than stock. To date, we’re unsure as to whether anyone else has attested an aftermarket valvetrain on a Modular engine, but it appears that there’s plenty of untapped performance and this makes us wonder what else there is to uncover with a little R&D.