Jeep Engines - Oljeep

196 MOPAR PERFORMANCE PARTSIIInnerDamperunder the “if it’s good for Super Stock, it must be good forme” theory. The second way is to have a big camshaft in theengine with its required big valve spring, and then removeit and swap in a medium-sized hydraulic camshaft andforget about replacing the valve springs. Either of theseapproaches on a hydraulic camshaft, or even a smallmechanical camshaft, can cause failures such as scuffedcamshafts, worn out tappets, and broken rocker arms. Thesprings that worked well with a high lift roller just don’twork and cause all kinds of failures when used with smallerprofiles. Always refer to our camshaft application charts forproper valve spring usage.Valve Spring Installation Performance TipsIOuterFigure 4 - 33Big Camshaft Valve Spring ConsiderationsEngine builders have a tendency to forget some basicswhen they are changing camshafts. Camshafts are so easyto change and are changed so frequently it’s easy to miss anitem. The most common mistake is to forget to replace thevalve springs.This can be a problem when bigger camshafts are installedor when smaller camshafts are swapped in. One commonproblem occurs when a stock hydraulic camshaft or smallRV design is replaced with a big, high lift unit. If you don’treplace the valve springs so they match the new camshaft,you’ll have problems ranging from lost performance tobroken parts.Another problem-too much valve spring can be evenworse. This is usually arrived at in one of two ways. First isthe racer who wants the BEST valve spring, and worksAt first thought, the installation of valve springs sounds toosimple to even consider. The valve spring sits between theretainer and the spring seat in the head. For performanceapplications, there are some tricks to this simple system whichshould be considered. Racers can use single springs, dualsprings, or triple springs, each one having special challenges.Production engines typically use single springs, whichsometimes include a damper. The most important itemrelative to valve springs is the installed spring height - thedistance between spring seat in the head to the underside ofthe valve spring retainer. With a single spring, such as usedin production, you can use stock retainers, keepers andgood umbrella (Viton) valve seals (P4529240). Checkingthe installed height assures that it is installed correctly.The next most important item is to select the spring that’sright for the camshaft. Each Mopar Performance Partscamshaft has a specific valve spring, listed by part number,that should be used. If it is not a Mopar Performance Partscamshaft, then the camshaft lift must be known to select theproper valve spring. Once the proper spring is selected and theinstalled height checked, all that remain are some quick tips.1. Basic GuidelinesThe following are some basic guidelines to followwhenever you install valve springs in yourperformance engine:a. Valve springs should be load checked. Weak oneswill have to be replaced. Record loads and heightchecked at.Note: Not all spring testers are the same. Manyare not maintained and calibrated on a frequentbasis. This makes the absolute value of springloads quite unreliable. However it is a very goodcomparative tool; that is, measuring all springs onthe same tester or measuring the same spring newand used.The biggest advantage of load checking is to see ifthe springs have “gone away” or to see if a secondset of the same spring is as “strong” as the firstwhich worked well.