Editing Camshaft install tips and tricks (section)
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===Valve springs=== '''7. Failure to use acceptable valve spring pressure for cam break-in.''' You can't use 350 lb. over-the-nose springs and expect the cam to live through break-in. Assemble the heads with stock or weak single springs (only if those springs will accept the amount of valve lift and the retainers will clear the valve seals/valve guides) to break in the cam, then use one of the many tools available to change the springs with the heads on the motor. Those without a compressor to hold the valves up for this operation can feed some clothesline cord through the spark plug hole and then bring the piston up to smash the rope and hold the valves up. Alternatively, assemble the heads with the springs you will run and use reduced-ratio break-in rockers, then change out the rockers after break-in. Although expensive, these are available from [http://crower.com/ Crower] in various ratios for different motors. A popular ratio for a small block Chevy would be a 1.3:1 rocker. In other words, let's say the lift at the cam is 0.350" and the theoretical lift at the valve with 1.5:1 rockers is 0.525". Using the 1.3:1 rockers would result in lift at the valve of only 0.455", thus reducing stress at the camshaft/lifter interface during the crucial break in period. Of course, you may have to elongate the pushrod holes to accommodate the longer rocker arm pushrod cup-to-pivot dimension, and/or alter the slots in your guide plates. Be aware that reduced ratio rocker arms will ''by themselves'' do nothing to lessen the '''seat''' pressure. Things that will change the seat pressure are a different installed height, or a different spring rate. Also be sure to do the math to be sure the reduced ratio rocker arms will reduce the open spring pressure to acceptable levels for break in; don't assume ''anything''.
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