Mark recommends using a liberal...
Mark recommends using a liberal dose of Royal Purple Max-Lube assembly lube on the pushrods, springs, and pushrod cups as the rocker assemblies are installed. Note the difference in widths of the slots in the rocker stands. Exhaust rockers are placed in the more narrow slots (left) and intake rockers are mounted in the wider ones.
Our former tech editor, Mark Houlahan, stepped in to bolt on the new rocker system. Although our Twisted Wedge heads used studs initially, the new shaft-mount system is designed to bolt directly onto the heads. There's no need to modify or remove them from the engine to install the rocker arms.
We feel compelled to reiterate the message to NMRA Real Street racers that Crane's Pro-Series, shaft-mount rocker arms aren't legal for the class, so don't get any crazy ideas about trying to bend the rules. You never know when you'll be asked to remove a valve cover so tech officials can take a closer look at your rocker arms. If you want to run a Real Street-style combo in your street/strip 'Stang, anything goes.
Crane's new Quick Lift rocker-body design provides an initial valve-opening rate at least 0.100 inch higher than the advertised ratio. It then decreases through the first 0.300 inch of net valve lift until the advertised ratio is achieved. It's maintained until the valve is within 0.300 inch of the seat, where the ratio then goes back to 0.100 inch more than advertised.
This varying ratio is a result of the pushrod seats' location in the bottom of the rocker bodies. Quick Lift aluminum bodies have a lower pushrod-seat location compared to other rocker-arm bodies, causing pushrod tips to contact the rocker bodies at lower points in the pushrod seats' operating arc.
This change in effective rocker-arm ratio has been proven to produce horsepower and enhance throttle response.
Intake/exhaust rocker-arm tandems are mounted on 5/8-inch shafts. The rockers' retaining snap ring is placed in a groove machined into the middle of the shaft, and thrust washers are placed on both sides of each arm (0.015-inch/intake and 0.031-inch/exhaust). Make sure you have four individual thrust washers before installing them; they have a tendency to stick together and give the impression there are fewer than four. Don't be stingy with the assembly lube during this process. Mark uses an Allen wrench to fully seat the pushrod-adjustment set screw, and then backs it out one full turn. This ensures that the internal oil passages in the adjusters align with the rockers' oil passages, eliminating any chance of binding the pushrods when the rockers are installed.
Each shaft is mounted to its stand using 1.25-inch, 5/16 Allen-head bolts on the outside, to the right and left of the intake and exhaust rockers, respectively. A shorter 5/16 bolt (1.00-inch) goes in the area between both rocker arms.
The long and short shaft bolts are torqued to 28 lb-ft.
Mark confirms we have correct intake and exhaust-pushrod length by preloading the lifters. This process is no different than the way it's done with stud-mount roller rockers. Here, he uses the wiggle technique on the rocker arm while turning the pushrod-adjustment set screw. When proper setting is achieved for each of them, 7/16 adjustment-screw jam nuts are torqued to 24 lb-ft.
The blinging brightness comes from the Mikronite finishing process that each Pro-Series rocker arm undergoes for strength and smoothness. The Mikronite improves durability and impact resistance on each rocker arm while reducing friction, resistance, and corrosion. With Robin's SpinTron data as our confirmation for now-Real Street's engine wasn't in dyno-test condition when the swap was performed-we're sure the new Pro-Series shaft-mount rockers will do a better job of keeping our valves under control as rpm increases. With the Quick-Lift geometry in Crane's new arms (see sidebar), we wouldn't bet against Real Street's 306 gaining a few additional horsepower.
We experienced a clearance problem with the OEM valve covers, as well as several others we thought might work. This is the pile of failed attempts.
Our friend Mark Lambacher turned us on to this set of Trick Flow's tall covers (PN TFS-51400802; $122.95). They fit without any clearance issues. Trick Flow's 1-inch intake spacer kit is required for clearance between the covers and our Track Heat intake manifold; an optional oil fill/breather tube is available for the Trick Flow covers. Drilling a 1 1/4-inch hole in the passenger-side cover is necessary for installing any breather system.