TECH-LINE

ROCKER MOUNTING

This illustration depicts a MILLER PRO-STUD™ rocker arm  sitting at MID-LIFT. The valve is .300" open (of its .600" total), and the valve spring is almost 1.710", .or 300" from its 2.010 installed height. Also shown is a sectioned view of the Miller STUD-BRIDGE™. NOTE where the trunnion axis is in relation to the roller axis. They are both in-line with each other, horizontally. Directly to the right is the depth of the valve tip below the trunnion axis, of .265". This is HALF the ROLLER DIAMETER. Since the Valve Lift is .300", subtracting .265" means the valve tip is 035" ABOVE the trunnion axis when CLOSED.

The rocker stud leans into the valve on the Small Block Chevrolet, 11 degrees, 20 minutes (11 & 1/3 degrees). The above represents a similar dimension, but this rocker length is more toward the Big Block Chevrolet. It is easy to see that the higher the rocker arm needs to be to accommodate longer valves, the shorter the distance between the trunnion and the valve will end up being.

If you use this linear thinking (straight line position of where the roller sits atop the valve), then you will easily miss setting the rocker arm's angle, which is what the priority is. There is no way to accurately place the roller in the middle of the valve AND have MID-LIFT geometry, UNLESS you are using rocker arms designed for these specific dimensions. That is why we standardized the VALVE TIP HEIGHT dimensions many years ago, just to avoid this. But what is important to understand, is that no matter where the roller tip sits on the valve, what is important is the angle of pressure. It needs to be at this 90 degree angle at MID-LIFT. As long as the roller is somewhere in the middle of the valve tip, it doesn't matter if it is .050" bias to one side of the valve center-line or the other. The valve guide is usually over 2.50" long, the valve stem is usually .342" diameter. This aspect ratio works out to over 7:1. Do you think that the valve guide cares, or sees .050" difference in effect of a pressure point pushing down on the valve tip? It's a rhetorical question. No. It doesn't. But what it does see, is "angles of load." If the roller is rolling across the valve tip, instead of pushing straight down on it for the majority of its arcing motion, then it will see the side load harmonics that go with this, even though in theory there is a "roller" tip. The roller does NOT roll anyway. The roller is only a pivot point of rotation.

The MEI STUD-BRIDGE™ is without a doubt a "stud-girdle" that obsoletes stud girdles as we've know them. Made from solid 7075-T6 bar, precision machined on 2-axis` for Patented, interlocking MEI 12-Point Chromoly adjusters and 1/2" 4130 Chromoloy "T-Bolts", which place STEEL on STEEL to lock EACH and EVERY rocker stud solid. TENSILE LOCKING! Conventional stud girdles merely sandwich two bars across studs, with a single, lowly 3/8" bolt straddled between pairs of studs. Not even close in gripping power to this Patented design. (CLICK PHOTO)