Spring Time: KBX Installs Project Evil’s Manley Valvetrain

Valvetrain parts are all about control as they govern how the engine inhales and exhales while it’s operating. To exert the maximum amount of control, valvetrain parts must be properly matched to the combination they’re being used with. Jon Bennett from KBX Performance provides us with insight into the Manley Performance Products valvetrain parts in the new small block Ford they’re building for Project Evil.

When planning began for the new heart of the Project Evil Mustang the goal was to build a small-block Ford that was capable of generating a healthy 1,800 horsepower with the assistance of a Vortech V-30 supercharger. Knowing what the end game was, Bennett and the team at KBX put their thinking caps on to create an engine that would be reliable and be able to produce the targeted level of horsepower. Part of this process was making sure the valvetrain selected could take the boosted abuse produced by the engine.

When you dive into the valve spring theory pool there are many opinions and ideas on how you need to select the springs for use in a boosted application. One of the biggest mistakes people make is trying to use springs that have entirely too much pressure for their combination. According to Bennett, the old-school thought process for valve springs doesn’t work on a build like this.

“You have to remember the majority of high-pressure valve springs were designed for engines that turn a lot of RPM like what’s used in NHRA Pro Stock. These engines are big-blocks with long valves and large valve diameters, which are a heavier part than what we deal with in small-blocks. We’re not spinning these engines to 10,500 RPM, we don’t have a big-block valve weight, so we don’t need the same spring.”

The Edelbrock SC1 heads that are being used as part of the Evil’s engine change things slightly in the valve spring selection department. Since these heads have a longer valve than most of the small-block builds that KBX does, KBX needed to address the spring pressure to make sure the valves are able to open and close correctly.

“Since these SC1 heads use the long valves they have more weight. To deal with this we may run 25-40 more pounds of pressure on the seat than other heads. Something like a TFS Hi Port head has a valve that’s over one inch shorter with a smaller valve head diameter, so it would need less seat pressure than these heads,” Bennett says.

Lobe valve action from the camshaft is another item that must be addressed when looking at the spring pressure you will want to use. For boosted applications like Project Evil, Bennett likes to use their JB series of cam lobes that were developed specifically for boost. This combination helps keep the valve in-check at the targeted RPM ranges these engines operate in when it comes to the spring and pushrod options KBX selects.

The Manley spring of choice for this engine that KBX used was the lightweight Nex Tek Dual Drag Racing valve spring. These springs have a 1.500-inch diameter and 405 seats with 1165 pounds of open pressure at 2.150 installed height. Going with a spring like this gives KBX several advantages in how they can set up the entire valvetrain so it can achieve optimum performance in a boost-filled setting.

“We will install these at a taller height to lower the seat pressure to our desired level. We chose the spring based on coil bind, which allowed room for our camshaft gross lift. We have been using the double springs for some time now due to lighter mass in the spring, which also lets you run a smaller diameter retainer for even more weight reduction due to the springs being only 1.500 diameter.  Prior to the double springs, we used triple springs which are 1.670 diameter with similar pressures,” Bennett explains.

The Manley valve springs are just one ingredient in the parts recipe that KBX uses to create boosted horsepower. To make sure the valve is locked in tight to the retainers, a quality keeper is needed for a high-performance application like this. To get the job done KBX selected a set of titanium radius groove keepers from Manley to eliminate valvetrain issues.

“We use Manley’s 10-degree version, and to my knowledge, we’ve never had a failure. Manley’s high-quality titanium material, coupled with their precise machining is our reasoning for selecting these. Manley also offers multiple installed height versions, -.050, standard, and +.050, allowing us to alter valve spring height on different applications, while retaining a standardized valve length and rocker stands,” Bennett explains.

A set of Manley retainers are also used as part of the valvetrain that’s attached to the SC1 heads. The retainers are tasked with making sure the valve stays compressed, while keeping the pre-load levels where they need to be.

“We want a lightweight retainer that has durability. We use titanium for our choice of material, and like the keepers, Manley’s quality of titanium, along with precise machining makes them a great choice. They also offer multiple installed height versions allowing us to alter valve springs height on different applications. This retains a standardized valve length which also keeps our rocker stand height standardized as well.” Bennett says.

With the help of KBX Performance and Manley Performance Products Evil’s small-block Ford will be able to use every pound of boost its Vortech supercharger can provide. Make sure you check out all the build updates for Project Evil right here as we continue to prepare the Mustang for action.

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About the author

Brian Wagner

Spending his childhood at different race tracks around Ohio with his family’s 1967 Nova, Brian developed a true love for drag racing. When Brian is not writing, you can find him at the track as a crew chief, doing freelance photography, or beating on his nitrous-fed 2000 Trans Am.
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