Valve spring tech
m (Add images) |
(→Valve spring rate: add text, link) |
||
| Line 74: | Line 74: | ||
*If the clearance is insufficient, different retainers or keepers (available in +0.050" size) can be used to correct it, or you can cut the valve guide bosses to correct the issue. An alternative is to use longer valves, just remember that using longer valves will alter the installed height of the valve spring. Most valves are available with stems that are 0.050" or 0.100" longer than factory specification. Adjust your shim thickness accordingly. | *If the clearance is insufficient, different retainers or keepers (available in +0.050" size) can be used to correct it, or you can cut the valve guide bosses to correct the issue. An alternative is to use longer valves, just remember that using longer valves will alter the installed height of the valve spring. Most valves are available with stems that are 0.050" or 0.100" longer than factory specification. Adjust your shim thickness accordingly. | ||
| + | |||
| + | ==Valve spring design== | ||
| + | |||
| + | ===Beehive=== | ||
| + | ;From [http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/viewall.html David Vizard]: | ||
| + | <blockquote> | ||
| + | With gains from conventional materials at a near standstill, the other option spring specialists had was to look at spring design to see if there was a better alternative to the parallel-wound conventional spring. Turns out there was, and during the mid 1980s GM began research on the application of a design known as the "beehive" spring. As its name suggests, this spring is wound in a beehive form. With each coil getting progressively smaller, this spring has no clear-cut resonant frequency. As soon as it starts to resonate at a particular frequency, the resonant frequency changes. Result: Spring surge is, in almost all applications, reduced to levels bordering on insignificant.</blockquote> | ||
| + | [[File:Beehive vs conventional.jpg|right|350px]] | ||
| + | <blockquote> | ||
| + | The beauty of the beehive spring is that it uses its delivered force far more effectively than a conventional parallel-wound spring. It needs far less of its delivered force to control its own motion, so this leaves more to control the valvetrain. This means less overall valve-spring loads while delivering more rpm. Our spin tests on a street roller cam showed an rpm increase from 5,950 to 6,900. This was achieved with a beehive spring (Comp Cams p/n 26918) with 8 lbs. less on the seat and 20 less over the nose than its parallel-wound counterpart. Because of the propensity of hydraulic roller lifters to collapse easier than their flat counterparts, beehive springs are well-suited to hydraulic rollers. Reduced loads and better control pay off in terms of added output and rpm. The two occasions tests were run, both in small-block Fords (302 and 392 based on a 351W), showed about a 6 hp gain in each, but considering just the change in peak hp is only a small part of the story. Take a look at the graph showing the before and after tests of the beehive spring (right). What you see here is a valvetrain that retains control to significantly higher rpm. The regular spring, in spite of being stronger, hit valvetrain crash at a shade over 6,000 rpm, but it was progressively losing control (or collapsing the lifter, or a combination of both) at 5,700 rpm. The beehive spring kept it all together up to about 6,600, although power figures were only recorded to 6,400. At 6,000 rpm the beehive's ability to deliver superior control netted an increase of some '''65 hp'''. | ||
| + | </blockquote> | ||
==Valve spring rate== | ==Valve spring rate== | ||
Your Privacy Choices