Info regarding the revised 144832 Crane dual spring
08-17-2004, 05:52 AM
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Info regarding the revised 144832 Crane dual spring Most of you probably don't know this but Crane just revised the 144832 double spring (material change). In the past, Thunder recommended shimming the 832s to 1.770 installed height for TReX installations. I got a set of the new springs and Jason99T/A just checked them out on his spring tester and said these can actually be shimmed much more to increase seat and open pressure.
Here is what Crane has posted about them:
Here is what Crane has posted about them:
My name is Mark Campbell and I am VP or R@D at Crane Cams. Eight months ago, we (Crane) decided we wanted to improve our 144832 valve spring to minimize load loss at extreme RPM. The spring has what we consider to be the best harmonic characteristics for its intended use (this is a result of physical design characteristics, not material), but we could see that some LS1 guys were operating at RPM levels above 6500RPM frequently and that was drastically accelerating load loss. We merged an improvement of the 144832(changed the material to a much improved alloy) with the design of some new springs that used the same wire diameters. When the new versions of the 144832 (identified by a blue stripe and a yellow stipe) came in, we had to Spintron test them for quality. They worked beautifully and had only 1/3 the load loss of the original 144832's. In fact, this material is so lightly stressed that these springs will take .700" lift when installed at 112# @ 1.800" (and still have .060" additional travel). In fact, they can be shimmed .060" to give 133# on the seat and still take .640" lift safely. This is all with keeping the great harmonic characteristics and low noise signiture to eliminate false KR!
08-17-2004, 02:36 PM
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I bought a shim kit that had 16 .015, 16 .030 and 16 .060 shims.
You can get this and run a .060 and .030 shim under each spring seat
http://store.summitracing.com/partde...CCA-4753&N=120
You can get this and run a .060 and .030 shim under each spring seat
http://store.summitracing.com/partde...CCA-4753&N=120
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08-27-2004, 02:34 PM
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Hello, this is Roger Vinci and I wanted to comment on spring failure.
I have been told some people are running as liitle as .004 lifter preload rather than .060 to .120 which is the preload VHP recommends. Apparently their cam manufacturer has given them this advice. As you know, the aluminum heads experience significant thermal expansion which would make the preload negative and, in fact, cause the rocker to have lash rather than preload. The result of this misconception is severe valve train noise, knock retard, power loss, and worst of all, severe trauma to the valve springs, which causes premature spring failure. Hydraulic roller camshafts have no clearance ramps and therefore must have lifter preload. We have done extensive dyno testing at our VHP facility and found significant power increases, as well as, much quieter valve train with lifter preload of .060, .090, and .120. Do your self a favor. Try running lifter preload in these ranges. This is easy to accomplish with VHP, or CRANE fully adjustable roller rocker kits.
I have been told some people are running as liitle as .004 lifter preload rather than .060 to .120 which is the preload VHP recommends. Apparently their cam manufacturer has given them this advice. As you know, the aluminum heads experience significant thermal expansion which would make the preload negative and, in fact, cause the rocker to have lash rather than preload. The result of this misconception is severe valve train noise, knock retard, power loss, and worst of all, severe trauma to the valve springs, which causes premature spring failure. Hydraulic roller camshafts have no clearance ramps and therefore must have lifter preload. We have done extensive dyno testing at our VHP facility and found significant power increases, as well as, much quieter valve train with lifter preload of .060, .090, and .120. Do your self a favor. Try running lifter preload in these ranges. This is easy to accomplish with VHP, or CRANE fully adjustable roller rocker kits.
