To go with our cam, we ordered a set of Comp's (PN 829-16) solid roller lifters. These Comp lifters drop right into a production big-block Mopar with no modifications to the block or oiling system required. The correct pushrod length for the solid roller is different than what is used with a hydraulic flat tappet, so the required length was found by mocking up the combination with a length-checking pushrod. Custom pushrods were ordered from Smith Brothers. To provide valvetrain control, selecting an appropriate spring is vital. The spring seats in the Indy heads are machined to 1.550-inch diameter, so that set the spring diameter spec. We looked no further than the Comp Cams spring chart to find PN 999-16. These are an H-11 tool steel spring set, which delivers 196 pounds of load on the seat at an installed height of 1.900 inches, and 608 pounds at .650-inch lift. With that kind of spring load, we would easily cover any question of valve control with our combination. To go along with the springs, we selected Comps' (PN 732) titanium retainers, and (PN 611) 10-degree SuperLocks to fit the single groove 111/432-inch stems of the Indy valves.
There are a few other considerations when making the swap to a roller cam. All roller cams feature the three-bolt front nose, as factory fitted in Six Pack 440s. Our hydraulic cam was ground on a conventional single-bolt core, so we need to upgrade the cam drive to a three-bolt style. We went with Comp's top-of-the-line, billet-steel, adjustable timing set, (PN 3125 KT), which features a hex adjustment eccentric at the indexing pin. The adjustable timing set allows the cam phasing to be infinitely adjusted +/-6 degrees by simply loosening the three mounting bolts on the cam gear, and turning the adjusting eccentric with an Allen wrench. The adjustability makes it easy to degree-in the cam to an exact setting, and also greatly facilitates cam-timing changes on the dyno when dialing in the combo. To make changes to the cam timing even easier, we modified our stock timing cover with a cam access plate. A roller cam installation in a big-block Mopar will require a thrust button to control forward cam thrust. We handled that with a Comp Cams (PN 206) nylon button.
The final item to address is the distributor drive, since roller cams are ground on steel billets, making them incompatible with the factory steel drive gear. A Milodon distributor drive with a bronze gear had us covered there.
The Dyno
With our 440 re-assembled, it was time to quantify the value of our mods on the dyno. We intended to start with the ported Indy 2D two-plane intake manifold, topping the engine with the same Demon 850 carb we had run in the previous test session. Unfortunately, our 2-inch Hooker SuperComp headers were not available to us on test day, but we did have a set of tti 2-211/48-inch step headers at Westech's dyno facility. We had tested these two headers back-to-back in a previous test, and found the results very close on a 650hp, 452-cube RB. Upon firing and warming up the engine, we detected a problem in the ignition system, which was traced to the magnetic pick-up in the distributor contacting the reluctor in the Mopar distributor. With the distributor damaged, we made an expedient change to a MSD distributor, which also required changing the right side valvecover for clearance. We would not expect the distributor change to have an effect on output.