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Break in period

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A valve spring is chosen by the cam maker to keep enough pressure on the valvetrain so that the lifter and lobe never loose contact with each other and no more to minimize wear rate. That pressure is chosen not only on profile but on an expected RPM hard limit. Lets say 6500 is that limit. When the motor is spun to 6700 the lifter and lobe have the same relationship as a jackhammer and the concrete street it is destroying. In all likely hood the driver will feel the resultant valve float and take his foot off the loud pedal. He thinks that because he drives home just fine that no damage has occurred. Truth however is that the spring was damaged and that hard limit is lowered a few rpm each time this is done. He may do this off an on for years but as 95% of his miles are at steady state 1500 rpm he believes with all his heart that floating valves won't hurt a thing. Then one day he misses a shift, and BOOM, drops a valve, kisses a piston, breaks a rod, daylights a block and for the life of him will blame everything on the planet other that a damaged valve spring.  One he has been killing for years. He believes this because the tattletail on his tachometer says the motor never got past 5800 rpm. 


Same principle and breaking a coat hanger buy bending back and forth till it fails.

If it takes 10 cycles to fail and you never go past 8 then it is hard to convince you any number of cycles will break wire. 


People do this with oil and with filters every day. Lingchi......


They will go to their grave believing that because THEY never had a failure, they caused no damage.



Edited by Grumpy Bear
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