Power Multipliers

THINGS TO CHECK
Anytime you plan to up the rocker-arm ratio there are several points that need to be checked:

PISTON-TO-VALVE (PTV) CLEARANCE
Increasing the rocker ratio adds lift that could cause the valves to tap the pistons if they were close before. Since an increase from a 1.5 to a 1.6 ratio only nets about 0.030-inch total extra valve lift, and total valve lift is not what you're checking when you look for PTV clearance, this may not be an issue. A minimum of 0.100-inch intake and 0.080-inch exhaust clearance is recommended.

RETAINER-TO-SEAL CLEARANCE
With your rocker arms properly lashed, check to make sure there's about 0.030-inch clearance between the spring retainer and valve seal at max lift. This check is easiest to do with checking springs installed. You can also measure the total clearance with the valve closed and subtract your total lift to calculate the clearance. Remember to calculate lift using the new ratio.

VALVESPRING COIL BIND
This only requires you to find your valvespring's installed height and subtract the coil-bind height to find out how much lift your springs can take. It's best to keep a minimum of 0.030-inch between a few coils if you want your springs to live.

PUSHROD-TO-HEAD CLEARANCE
Increasing the ratio of a rocker arm could make the pushrods hit the head or guide plate. There's really no way to check this without installing the new rocker arms and cycling the engine by-hand. Carefully check under and around the guideplate to make sure the pushrod doesn't hit.

ROCKER ARM-TO-RETAINER CLEARANCE
If you're installing big-diameter springs, make sure your rocker arms don't hit the retainers. To cure this you can install lash caps on the valve stem tips. There are also many different height valve locks to try, but that will affect your spring's installed height. Also, not all retainers are created equal and you might be able to find a different set that will clear.

HOT ROCKERS
The new kid on the block is definitely Hot Rockers from Everoc Industries. This unique system gives your engine the best of all rocker ratios automatically. By switching ratios as you drive, Hot Rockers gives great low-end grunt and fantastic economy along with a smooth transition to a high top-end ratio for more power. Hot Rockers are basically a full-roller, shaft-mounted design that offers stability and reduced friction at the valve tip as well. We haven't had the chance to test Hot Rockers yet, but plan to do so soon. We'll let you know all about them in an upcoming story. Check out www.hotrocker.com to learn exactly how this ingenious system works.

The Hot Rockers system works...        read full caption The Hot Rockers system works by shifting the fulcrum pivot of the rocker arms as you drive. All rockers will shift together, so you cannot run different ratios on the intake and exhaust. The four-position fulcrum provides ratios from 1.1:1 up to 1.75:1 (higher and lower ratios can also be specified). An ECM shifts the ratios at user-defined rpm points via an electric motor mounted on the valve covers.