When it comes to making horsepower,...
When it comes to making horsepower, cam choice is critical. We ordered a custom spec, Competition Cams solid roller grind based on the numbers Cam Masters, a cam selection consulting service, provided for our specific engine combination. The cam is being checked on a Cam Doctor cam reader, which loads the lobe profile into a computer, providing a graphical analysis of its dynamics, as well as calculating the true seat timing with a given lash and rocker ratio.
If it were just opening new parts boxes and bolting-up the pieces, there would be no reason to call it engine building. Rather, it would be the simple task of engine assembly. Most of us who have a few years of wrench-turning under our belts are familiar with bolting together an engine assembly-especially with familiar mills such as our Mopar big- and small-blocks. Put together an engine in near stock form, and the process comes down to carefully assembling the pieces. The factory did the engineering homework, leaving us to make sure the package comes together according to the specs. Ditto for package combinations in various engine kits. The supplier (hopefully) has worked out the parts' combination, so all we need to do is screw everything together. Dip deep into a wide range of aftermarket catalogs and dream up a radical combination of your own, however, and the responsibility for making it work falls on your own shoulders. This is where the term "building" enters the equation.
The further away from stock form we go, the more keyed-in the builder has to be, not only to churn out mucho horsepower, but also to ensure that the thing will make it past the first turn of the crank.
The roller grind can achieve...
The roller grind can achieve much higher velocity than a flat tappet, meaning the valve will reach full lift faster. On the left is a stout hydraulic grind. Notice the roller's lobe, right, is much more squared off in profile, giving a serious increase in area under the valve opening curve.
Last month, we assembled our 440's basic bottom end. Although our bottom end included trick aftermarket Eagle rods and Arias pistons, that much of the job did not differ greatly from a stock rebuild. The clearances were set, and as long as the machinists did their job, we were home free.
This month, we will complete the lubrication system, the cam and cam drive, finish the heads, and set up the valvetrain. The question remained of whether we would assemble a fairly conservative package, or build something radical. As we weighed the possibilities, we decided to go radical. The goal-build as hairy a factory iron head 440 combination as we would dare, and cheat with every trick we know, so we could drive it on the street. Probably not "drive to the grocery store" street, but rather 8 inches of choppy vacuum at 1,100 rpm, four-speed, 4.56-geared; Cuda street. Yes, our 'Cuda would continually ask with its lopey idle, "Wanna drag?" We'll spill it all in the next few issues, and run a dyno test on this baseline package to show how we did.
The roller uses the high-performance...
The roller uses the high-performance three-bolt cam gear nose. Lube up the journals and carefully slide in the cam, using a long bolt as a handle. Lobes will be lubed later, as they are easy to get to on 440s once the cam is installed.
Most roller cams are ground...
Most roller cams are ground on steel billets, which means a common steel distributor drive gear will grind itself to oblivion on the cam gear. Milodon's aluminum bronze gear takes care of that.
For rockers, we opted to step...
For rockers, we opted to step up to a 1.6:1 ratio, for brutally quick valve action with our Comp Cams roller cam. Stamped stockers (top) were non-adjustable, and plain out of their league in this type of application. The Comp Aluminum rockers (below) feature a 1.6:1 ratio, a roller tip, and needle bearing fulcrums. Get the complete kit, since the shafts and spacers are special. Unlike flat tappets, roller lifters (bottom right) are joined in pairs with a link bar, which holds the rollers in line with the lobe. Factory pushrods were out. We ordered a Comp adjustable checking pushrod (middle, left) to determine the required length.
The Competition Cams high-ratio...
The Competition Cams high-ratio roller rocker setup is a bolt-in, but doesn't include new hold-downs. The stockers (arrows) must be ground or filed to center the roller tip over the valve, and to provide adequate clearance between the rockers. We filed our stock retainers to give .005 inch between the rockers.
With a shaft-mount system...
With a shaft-mount system bolted in the stock location, the valvetrain geometry is fixed at the valve side of the rocker with a given valve length. The stock location and valve length gave us excellent geometry at the valve side, with the roller correctly sweeping across the valve tip. Varying the pushrod length, while keeping the lash constant, however, will change the angle made between the pushrod and the adjuster in the rocker. This will affect the lift at the valve.
Actually measuring the effect...
Actually measuring the effect of changing the pushrod length showed that lift varied by up to .011 inch, with less lift being delivered with a short pushrod, and the adjuster set lashed up when all the way in. Lift increased with a longer pushrod, so we set the length to allow the adjuster to give the required lash toward the top of the adjustment range (one thread only showing on the adjuster at the bottom of the rocker). The Comp rockers actually exceeded their rated 1.6 ratio, delivering .667-inch lift on the intake and .675-inch lift on the exhaust, with the lash set at .024 inch and .026 inch, respectively.