Page 15 of Lunati Valve Train by Holley Performance Products, Inc.

valve train valve spring technical information cams valve train valve spring technical information how to get the most out of your lunati valve springs · valve spring fitment valve spring pocket clearance valve spring pocket clearance is the gap between the inside diameter of the valve spring pocket or cup if used and the outside diameter of the valve spring · too much clearance will result in the spring dancing around in the head which beats up the spring mounting surface and the spring itself if this is the case a spring cup may be used additional machining of the spring pocket may be required to accept the spring cup · not enough clearance will bind the spring in the pocket overstressing the bottom coil by limiting its movement and not allowing the spring to grow this will cause the bottom coil to wear against the head and/or prematurely fail machine the valve pocket using a spring seat cutter if not enough clearance exists rods cranks pistons valve spring retainer fit the valve spring retainer should fit the valve spring being used a slightly snug fit is acceptable however a fit that is too tight can overstress the top coil and cause it to fail a fit that is too loose can lead to spring dancing valve spring installed height the installed height of the valve spring is the distance between the valve pocket or cup or shims and the outer edge of the spring retainer which is the height of the valve spring when the valve is closed to check installed height follow the following procedure 1 install the valve in the guide 2 install the retainer and valve locks 3 install all spring cups and/or valve spring shims basically everything except the valve spring 4 hold the valve closed by pulling the retainer up tightly against the valve locks 5 measure the distance between the outside edge of the valve spring retainer and the spring seat a snap gage or a height micrometer should be used 6 check the distance against what is recommended on the camshaft specification card an installed height of 0.020 is acceptable 7 if the installed height is not within 0.020 either machining of the valve pocket or removal/installation of valve spring shims is necessary 8 repeat this procedure for the rest of the valves apparel engine kits 198 www.lunaticamshafts.com

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