Providing the spin for the cam is the Milodon geardrive. It offers accuracy, reliability,
The Heart of the Matter
OK, it's down to the brass tacks now-cam selection. No other component on your parts shopping list sets the scene in the same manner as the camshaft. The cam choice will largely define the running characteristics and temperament of the final engine combination. How much power that can ultimately be produced, as well as the rpm capabilities of the engine, will be made or broken by the cam selection.
For the big-block Mopar, there are three choices-flat tappets in either hydraulic or solid, or solid roller. Each of these has its advantages and disadvantages relative to one another, but for ultimate power production, there is really only one choice-solid roller.
Setting up the geardrive begins with removing the stock front-cover locating dowels (we ha
With the solid roller getting the nod in the cam department, it came down to specifying a bumpstick for the task at hand. We wanted to get more scientific in our selection process, rather than flipping the pages of various cam manufacturers' catalogs. We turned to a relatively new service in the aftermarket industry, Cam Masters (see sidebar "Cam Do It," p. 45), to run the numbers.
Having the numbers, in terms of overlap, duration, lift, lobe separation angle, and installed centerline is only part of the picture. Actual lobe design and dynamics play a vital role in determining valvetrain stability and longevity. Cam Masters does not grind the cams, but at the back of every manufacturer's catalog is the lobe specifications section.
Generally neglected by the weekend warrior, these are the pages where the top level professional engine builders mine for info in selecting lobes to build custom cam combinations. We dug into the roller cam lobe specs section of the Competition Cams catalog to find our lobes. To gain longevity, we were after lobes with less aggressive dynamics than the Pro drag racing designs, but much hotter than a typical street roller. So, we focused our attention on the endurance race oval track lobes section.
The case is installed finger-tight, and the cam cover plate is removed. The outer gear is
On the intake, we went with the NC series 4149-a Busch Grand National oval track lobe-which is super-aggressive on the opening and easier on the closing. Specs come in at 292 degree-rated duration (260 at .050 inch) and a lobe lift of .421 inch. With the recommended lash of .024 inch, that results in a theoretical valve lift of .650 inch with a 1.6:1 rocker. On the exhaust side, we chose Competition Cams' High Tech .420-inch Exhaust Series, again an oval track lobe, designed to be easier on the valvetrain than Comp's most aggressive designs. Specs on the exhaust are 296 degree-rated duration (258 at .050 inch) and a lobe lift of .420 inch, giving a theoretical lift of .646 inch with 1.6 rockers. As spec'd out by Cam Masters, the lobes were ground 107 degrees apart. There's no way we are claiming maintenance-free 100,000 mile reliability with these radical lobes, but with careful attention to keeping the valvetrain weight to a minimum, and holding spring load as light as possible, consistent with proper control, we expect to achieve respectable life.
Backing up our roller cam, we went with Comp's PN 829 roller lifters. Although Comp lists lifters for the 440 in various pushrod heights-even some with offsets for increased pushrod-to-head clearance-the standard height, non-offset PN 829s are ideal for our iron-head 440. Built with a roller wheel made from an exotic steel nickel alloy of a much higher grade than the ball bearing steel commonly used, we weren't worried about durability in our application. The Comp lifters have been proven in full race engines at 10,000-plus rpm with valve-spring pressures of as much as 1,000 psi over the nose. If they can live under that kind of punishment, handling the requirements of our 440 should be child's play.
Slide the case over to the right, to get rid of any lash between the gears with the newspr
Once the case is locked down in position with the correct gear clearance, the stock dowel
The supplied tapered 51/416-inch dowels are driven in with a brass drift to finish the job