COMP Cams How to Set a Valve Lash

in this quick tech video we're going to demonstrate how to set valve lash as well as explain why the process is vital to the health of your engine valve lash is the mechanical clearance in the valve train from the valve tip to the rocker arm in a pushrod engine using solid lifters excessive lash will cause noise in the engine and wearing the valve train while lashing too tightly will hang open the valve and the cylinder won't run instead of making compression air will blow through the valve thus proper valve lash is critical to optimum engine performance it comp cams we use zo IC which stands for exhaust opening intake closing this is just one method but there are others the EO IC method works for any push rod engine using solid lifters with the valve covers and spark plugs removed and the rockers on screw the poly locks of the rocker arms until they are just finger tight then rotate the engine until the exhaust push rod on the cylinder that you're working on begins to move upward you will be looking for any rocker arm movement this is the process of exhaust opening at this point you can adjust the intake because the intake valve will be closed ensuring that the intact lifter is on the base circle of the cam this is particularly important as you run the risk of hanging open a valve if flash is adjusted while the lifter is not in this position place a feeler gauge between the valve tip and the rocker arm tighten the adjuster nut of the poly lock until the proper lash is found when you get to your preferred lash hold the adjuster nut in place and set it with the inner screw using an allen wrench the Polly locket jester nut adjusts the amount of valve lash while the set screw locks it into place finally tighten with an adjusting torque wrench until it clicks at 20 foot-pounds of torque this tightens the adjuster nut to the inner set screw and ensures the video not come apart the lash on most engines is set anywhere from 12,000 to 20,000 s check your cam spec card for exact valve lash settings to set lash on exhaust rotate the engine again and wait until you see the intake valve open to full lift and start to come back up again simply watch for rocker arm movement you then can set lash on exhaust the same way you did with your intake valve some engine builders and racers use valve lash as a tool for tuning at the track tighter lash gives an engine more bottom indoor torque while greater lash creates more top-end or horsepower which is typically made in the higher rpm range however lashing a valve too tightly can hang open a valve while excessive lash will decrease the duration of lift in essence making a cam smaller again it is also critically important to make sure that the lifter is on the base circle of the camshaft so that you can set lash if you have lift lash will be incorrect and you can hang open a valve

Channel: Summit Racing

Views: 740,917

Keywords: Cam, How-to, Poppet Valve, educational, Valve, Valve Lash, COMP Cams, summit racing, rocker arms, cars, exhaust, Valve Covers, Summit Racing Equipment

Id: 3gMYWLMAzao

Length: 2min 52sec (172 seconds)

Published: Tue Feb 28 2012