Max Gain Valvetrain
Although we respect the stock, Chrysler-stamped steel rocker system with moderate hydraulic cams, we had already gone off the deep end in terms of cam selection, so there was no looking back when it came time to select the balance of the valvetrain. It's a fact that intake flow is the limiting factor in producing a max power 440 when using factory cast-iron heads. Even with our best ported heads (see "Going With the Flow, Part 2," Feb. '99) moving 34 percent more air than stock, extracting as much horsepower as we can depends on packing the largest charge possible into the cylinder. The most obvious way of doing this is to open the valve longer by adding cam duration. Our cam, within a 292 degree-rated duration, pushed the valve events as radical as we dared go, and beyond. Drag race rollers could be had to push this duration up another 20-plus degrees if you please, and make more high-rpm power, but power would just begin to turn on at a stock 440's redline. The alternative is to open the valve as fast and as far as possible in the 292 degrees we chose.

While some competitive engines were factory fitted with higher ratio rockers, Mopar big-blocks were factory fitted with 1.5:1 rated rockers. This combo worked well with the stock head and cam combination. With our modified heads producing excellent flow in the high-lift range, getting airflow there fast would pay off in horsepower.

To fire the valve open as quickly and as far as possible, we went to Comp's 1.6:1 shaft-mounted, aluminum roller rocker kit. With the radical roller cam, anything less than a needle bearing fulcrum to handle the required spring loads, and the roller tip-to-control guide wear just wouldn't cut it. The Comp kit contains shafts hardened to 57 on the Rockwell scale (stock shafts are a no-go), and the required spacers. The stock hold-downs are modified and reused, or, if you're handy, machine your own billet versions.

Valvespring choice, as previously mentioned, was a critical decision point, in terms of balancing the control of high spring loads with the longer cam and valvetrain life of a lighter spring. Generally, the recommended valve springs are spec'd to handle the maximum rpm a given lobe is likely to encounter. Although we were using radical oval-track lobes, our iron-head 440 will never come close to the 9,000 rpm for which these spring combinations are spec'd. With a maximum anticipated engine speed of 7,000 to 7,500 rpm, based on our airflow and engine displacement, we calculated a more livable spring rate of 180 psi seat pressure, and 480 psi over the nose would do the job. This also would dramatically increase the valvetrain life. Again, the Competition Cams catalog was tapped, and its PN 953 dual-valve springs were ordered.

Reliably putting a lid on a spring for high-rpm duty required a top-quality retainer. Since we wanted to minimize the valve spring pressure, lightening up the valvetrain was one of the major criteria. Light, yet strong, titanium retainers fit these requirements perfectly. We went with Comp's premium lightweight PN 720 Timetal 62 alloy 10-degree retainers. Locking them to the valve, we specified the 10-degree Superlocks, which are available with a specially machined recessed groove for increased clearance to the lash caps. All in all, it was a bulletproof combination.

Rounding out the valvetrain are the pushrods. In a highly modified engine, the chances of the required pushrod length being the same as stock are slim to none. With Comp's adjustable roller rockers, a pushrod with a cupped seat at the rocker, and a ball end at the lifter is required. For stock or mildly modified engines, Comp lists replacement pushrods by application. In the case of modified engines, factors such as block and head deck height, rocker arm design, cam base circle diameter, lifter pushrod seat height, and valve stem length all affect the required pushrod length. The best approach is to purchase a special adjustable length pushrod from Comp, and then determine the required length on the engine for the best geometry. We set our engine up with an adjustable pushrod, and mailed it over to the guys at Comp Cams for sixteen custom ones made to the same length. Comp stocks a wide range of pushrod lengths off the shelf, or they will build them to specs to match your combination. To keep the theme of a lightweight valvetrain, we went with Comp Cams' 31/48-inch Lite Hi Tech .065-inch wall pushrods. Made from super strong 4130 steel hardened to over 60 Rockwell, these pups are good for 9,000-plus rpm-totally worry-free in our 440.