VW PERFORMANCE PRODUCTS:
PERFORMANCE VALVE SPRINGS
Norris Performance Single Hi-Rev HD Valve Springs With Dampeners
Valve springs are super critical in setting up your heads to work with your cam properly. If your springs are too light for your cam lift, cam ramp profile, desired RPM range, lifter weight, pushrod weight, etc., you'll float valves. When you float valves, you'll not only lose power momentarily until they come back under control, you'll utterly destroy your heads in very short order. When you float your valves, they literally bounce off the seats, which can damage the valve job (sealing), cause your valves to stretch, cause valves to crack, cause heads to crack, cause premature lifter pitting and wear, bend pushrods, and otherwise cause all sorts of other catastrophic failures. A cracked valve can send a valve head through a piston in short order.
No fun.

If you have too much valve spring pressure, it can cause excessive valve train wear, lower horsepower, and higher termperatures due to excessive friction.

Norris Hi-Rev HD Valve Springs with Spring Dampeners
Way back in the early days of VW performance, it was discovered that Heavy Duty single valve springs added valve control to many applications. Spring tensions went up as horsepower increased. As they did, it was also discovered that premature failure was happening due to broken valve springs. As these springs flexed, they were creating a harmonic vibration that at certain RPM's was causing the springs to break, kind of like when an opera singer hits a certain note and breaks a champagne glass. A solution was sought to remedy this problem.

Hi-rev valve springs were soon fitted with spring dampeners, which were wound in the opposite direction as the primary spring. This countered the effect of the spring vibration, and was proven to extend the life of the valve spring as much as 100%.

Norris was among the first to take advantage of this technology almost 50 years ago. These spring dampeners are still available today. They require no machining to the heads, and slip right inside the Norris HD Single Springs. We believe in them to the point that we will not even sell single HD springs without the dampeners. Our Hi-Rev single springs test at 110 lbs at 1.55" installed spring height. These can be shimmed to the appropriate level to match desired compression tension, valve weight, and RPM range by adding spring shims underneath them, which are also available. They are naturally a hair on the ligher side compared to many aftermarket valve springs to allow them to be adjusted properly to avoid having too much pressure (lost horsepower) for your application.

Your machinist or head builder should know exactly how to match the spring to your particular head, cam, heads, RPM range, etc. If not, we'd be more than happy to help you choose the right combo. Proudly MADE IN USA.
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Norris Performance Dual Hi-Rev HD Valve Springs

There comes a point where a single valve spring, even with a dampener, will not keep a lifter against a cam, the valve from bouncing, etc. It is at this point where dual HD Hi-Rev springs are necessary. As mentioned previously, it is imperative that the valve train be kept tight to prevent a catastrophe. Norris recommends dual springs be installed for many applications where high valve lift, a steep ramp angle, higher RPM operation is desired; heavy valve, lifter and pushrod weights are used, etc. Many top builders recommend dual springs for almost any performance application. However, as mentioned before, there is a right time to use them. Norris was one of the first companies to recommend the use of dual springs for VW applications, and was one of the first to develop the technolgy to implement them... ALMOST 50 YEARS AGO!

Our Hi-Rev dual springs test at 130 lbs at 1.55" installed spring height. These can be shimmed to the appropriate level to match desired compression tension, valve weight, and RPM range by adding spring shims underneath them, which are also available. They are naturally a hair on the ligher side compared to many aftermarket valve springs to allow them to be shimmed and adjusted properly to avoid having too much pressure (lost horsepower) for your application.

These will require the machining by a skilled machinist to cut the valve guide boss properly allow for proper installation without coil bind. It's impossible to make a blanket statement to tell when they should be used, but your engine (head) builder should be able to make recommendations for you. If not, we'd be more than happy to make our own suggestions. Just drop us an email or give us a call. Proudly MADE IN USA.
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For ultra high reving engines coupled with steep and high lift cams, we recommend lightening the valve train with our other super lightweight components when running dual springs. Norris has super lightweight valve spring retainers and pushrods to help amaximize your valve train's potential. This will ensure most efficient operation and longest life from your engine.

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