Why not use my stock rocker arms?

Stock stamped steel rocker arms are not durable enough to handle the more aggressive loads of current performance camshaft profiles and valve springs. Ratios will also vary considerably on stock rockers from one to another, that coupled with the added heat andfriction of the stock type pivot robs power. Scorpion Racing Products rocker arms are fully CNC machined for ratio accuracy and strength. The roller bearing centerless ground fulcrum and roller tip lowers friction and heat.

How much power will I see by switching to Scorpion Racing Products roller rockers?

Typically you will see as much as a 15 horsepower gain from the ratio accuracy and reduced friction. A side benefit from the reduced friction is lower oil temperature, Scorpion Racing Products roller rockers generate half the heat of a stock type "ball" center pivot!

Which rocker ratio should I use?

Most engine/cylinder head combinations will respond to higher rocker ratios especially on the intake valve. When installing higher ratios, the engine "sees" more valve lift and a faster valve opening and closing rate. Remember the engine responds to valve movement not lifter movement! Any change inthe valvetrain (camshaft, rocker ratio or stiffer pushrods) that increases valve movement will increasepower. When installing higher ratio rockers the remainder of the valvetrain must be checked for clearance. Items to check are;valve spring travel (coil bind), retainer to seal clearance, pushrod to head clearance and in some cases piston to valve clearance.

How much more lift will I get with higher ratio rockers?

You’ll need to do some math here. Divide yourvalve lift by your rocker ratio, that will give you your cam lift. Now multiply your cam lift by the new rocker ratio to get your new valve lift. An example of .550 lift with 1.5 ratio going to a 1.6 ratio is, .550 divided by 1.5 equals .366 multiplied by 1.6 equals .586.

Will Scorpion Racing Products rockers fit under my center bolt valve covers?

Scorpion Racing Products offers rocker arms in both 1.5 and 1.6 ratios and 1.5/1.6 ratio sets (all with a 3/8 stud) in narrow body self-aligning and narrow body non self-aligning that were designed for the center bolt covers. You can view these at Scorpion Racing Products. You will still have to check for interference upon installation as there were many different covers produced with different internal baffling. You may have to do some minor modifications to these baffles.

How do I know if I need self-aligning rockers?

A stud mounted rocker arm needs to have a means of keeping the rocker aligned with the valve tip. The two common ways are guiding the rocker from the pushrod side (guide plate or slot in the cylinder head) or by capturing the valve tip (self-aligning) in the rocker arm. It is important that this is only done by either one of the two methods. In otherwords, the rocker must be held in alignment with the valve tip, but it cannot be guided from both the pushrod and the valve side at the same time. If your cylinder head has a slot machined into it or a pushrod guide plate, the non self-aligning rocker should be used. If you don’t have either of these then look at your stock rockers, if you see and indentation in the underside of the rocker that would capture the valve tip, then you would use a self-aligning rocker. A word of caution, some aluminum heads from GM had a "guide plate" on it and used a self-aligning rocker. This "guide plate" had wide pushrod slots in it and was usedfor engineassembly purposes at the factory only. This type of "guide plate" is not for holdingthe rocker in alignment, this head would use a self-aligning rocker.

How do I determine the correct pushrod length on my Scorpion Racing Products rocker arms?

When anycomponentis changed in the valve train the pushrod length must be checked. The pushrod length on a stud mounted rocker determines the rocker geometry which is very important for power and durability throughout the valve train. When the pushrod is the correct length therocker arm roller tip will sweep in the middle of the valve tip when the valve travels from closed, to full lift and closed again. This can be checked using an adjustable checking pushrod and some type of marking compound(bluing, grease etc.).With some marking compound on the valve tip and the lifterat the low portion of the cam lobe, install the pushrod and rocker. Adjust the pushrod length so that the roller tip is about a 1/3 across the valve tip towards therocker stud. Install the rocker adjusting nut to zero lash and rotate the engine to valve open and around to valve closed again. Remove the rocker, the pattern or sweep across the valve tip should be centered. If the pattern is closer tothe rocker stud, then the pushrod is too short, lengthen it and check again. If thepattern is towards the outside of the engine, then the pushrod is too long, shorten andcheck again. Keep in mind if you are using a hydraulic lifter you will need to bottom out the lifter (subtract the amountthe lifter is depressed from the ending pushrod length) or use a light checking spring in place of the valve spring. You do not want the lifter to be compressing while checking the pushrod length. Once the correct pushrod length is found, measure the overall length and contact us at Scorpion Racing Products for your pushrod needs.

What is the difference between the Scorpion Racing Products Race Series and the Platinum Series?

Both rockers use the same premium components, materials, will handle the same loads and will clear a 1.625 O.D. spring. The main difference is the rocker arm body itself. The Platinum Series rocker is profiled for up to a 34 gram weight reduction and has a reinforced top "strap" for additional strength and rigidity. Because the Platinum Series rocker body is profiled, it has a better chance of clearing lower profile valve covers. If you’re looking for maximum strength with minimum weight the Platinum Series is the one to choose.

Can I use high spring pressures with pedestal mount rockers?

Pedestal mount rockers are meant as a bolt on, mild performance alternative to the higher cost of removing the heads and machining for screw in studs, You have to remember there is only a 5/16″ screw attachingit to the cylinder head! The rocker itself is plenty strong enough, the attaching bolt is the weak link. However, when everything is correct it is possible to use open pressures as high as 350 lbs.spring load. The everything I’m refering to is: Hydraulic lifters only, Proper lifter preload, Correct spring loads for thecam and rpm, Do not tighten or loosen the attaching screw with spring pressure against it, Use a torque wrenchon the attaching screws, No mechanical interference in the valve train (coil bind, retainer to seal, etc.), Use a rigid Scorpion Racing Products pushrod, Do not over rpm the engine into valve float.

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