On the occasions when your rocker arm MOUNTING STUD is NOT installed to
the factory's angle,
THIS is what you will see. If you've set your pushrod length based on
the required formula of the first two steps, then after you've set the rocker
arm to MID-LIFT for your net valve lift with an inaccurate stud, the G-TooL won't flush out
in this final checking step. The illustration above shows the effect with a
pushrod that is too short, because the angle of the stud didn't lean into the
valve far enough. The ERROR occurred during the .700VL and .500VL steps, but
wouldn't be found until this third step. If the angle was MORE than the
factory's design, the GAP would appear on the front (roller end) side of the
adjusting nut.
Since the above GAP shows the push-rod is too short, rotating engine
CLOCKWISE (as you face the degree wheel) is what's required to close GAP; or
COUNTER-CLOCKWISE if it is on the other side of the stud. Be careful in this
process and note the difference, then divide by the rocker ratio, and change the
pushrod by this amount, in whatever length (shorter or longer) that your
engine's stud angle error requires. The above type of example would require
longer. When you've done this, measure the push-rods for the final time, and
CALL MEI for the correct length that is fit just for your engine. Round the
figures off to the nearest 10 thousandths.
NOTE
the 91° 16' (91.25 degrees) between the motion line and the valve centerline. It
should be 90° even. This 1.25° is 10% error! Because the rocker arm is only
moving about 24° total, and only the first half of this is critical to
intercepting this 90° point accurately. So 1.25° of the 12° MID-LIFT arc is
pretty close to 10%. Note how small this actual GAP is (which is precision
scale). That could easily translate into several degrees of extra
crank rotation to effect the same valve lift. With the G-TooL, you can easily
control your accuracy to within .002", and extract every last degree of
information from your cam!