VALVESPRING TECH AND FAILURE ANALYSIS:
MANY OF US HAD VALVETRAIN FAILURES OF ONE TYPE TO ANOTHER. THE MOST COMMON IS VALVESPRING FAILURE AND ITS DESTRUCTIVE AFTERMATH.
WE WILL TRY TO ANALYZE WHAT HAPPENED AND HOW TO MAKE SENSE OF IT ALL SO WE MAY START AVOIDING AND REPEATING THIS COSTLY MISTAKE!
"NORMAL" FATIGUE FAILURES OCCUR 1.5 TO 2 COILS FROM EITHER END OF SPRING!
-THIS IS THE AREA THAT SEES THE HIGHEST STRESSES FOR MOST RACING VALVESPRINGS>
THE ENDS OF THE SPRINGS!
The center portion of the spring "surges independently" from the end causing the transition area to be the most susceptible to failure....
SPRINGS THAT EXHIBIT FAILURE "NEARER THE CENTER" OF THE SPRING ARE THE RESULT USUALLY FROM DEFECTIVE QUALITY OR AN EXTERNAL PROBLEM.
SPRING LOAD VS. LIFT VS. COIL BIND:
-BE SURE TO INSTALL YOUR SPRINGS TO MAXIMIZE DISTANCE TO "COIL BIND" ( solid stacking of the coils )
WHILE AT THE SAME TIME PROVIDE FOR ENOUGH SPRING LOAD TO CONTROL THE VALVE.
USUALLY THE HEAVIER INTAKE VALVE WHICH WILL FLOAT/LOSE CONTROL MUCH FASTER THAN THE LIGHTER AND SMALLER EXHAUST VALVE.
THE ONE EXCEPTION IS WHEN THE EXHAUST LOBE PROFILE "ABRUPTLY" SLAMS SHUT THE EXHAUST VALVE CAUSING IT TO LOSE "TRAPPED" AND VALUABLE COMPRESSION PRESSURES AT THE END OF THE OVERLAP CYCLE.
-GENERALLY SPRINGS LOSE LESS LOAD THE FURTHER THEY ARE OPERATED FROM COIL BIND.
-"OSCILLATING" STRESS RANGE HAS THE GREATEST EFFECT ON FAILURES COMPARED TO THE AMOUNT OF SPRING LOAD!
EX. Spring installed @ 1.850 @ a max lift of .600
Spring installed @ 1.875 @ a max lift of .625
Adding .025 to the installed height at the same time adding .025 to the lift sounds ok but will increase the probability of "oscillating" stresses that will kill or damage the valvespring.....
Make sure you adhere to the installed spring height recommended and with the correct valve lift range designed into the spring package.
* ADVANCED VALVESPRING MANUFACTURERS USE A SPIN FIXTURE SIMILAR TO A "SPINTRON" MACHINE TO TEST WHICH SEVERAL SPRING OR SPRING COMBINATION WITH OR WITHOUT SPRING DAMPENERS TO SEE & EVALUATE WHICH ARE THE MOST "STABLE" OF ALL SPRING TYPES.
THINGS TO REMEMBER:
IN GENERAL LIGHTER AND STIFFER COMPONENTS IMPROVE DYNAMICS AND STABILITY.
VALVESPRINGS WITH HIGH SPRING RATES (STIFFNESS) ARE LIGHTER AND GENERALLY PERFORM BETTER.
DRAWBACKS TO THIS IS THE HIGHER OSCILLATING STRESSES EQUATE TO A RISE IN FAILURE RATES.
THE NEED THEREFORE IS TO MAXIMIZE SPRING RATE WITHOUT BEING TO CLOSE TO THE DANGER ZONE.
COIL BIND:
MINIMUM DISTANCE BETWEEN COILS IS .010 x NUMBER OF COILS.
6 COILS =.060 CLEARANCE
PUSHRODS APPLICATIONS OPERATE AT LARGER .070 TO .120 RANGE.
DOHC- SOHC ENGINES:
DIRECT ACTING OR SOHC/DOHC USUALLY OPERATE CLOSE TO COIL BIND TO PROMOTE "DAMPING" OF SPRING SURGE!
ALLOWING TOO MUCH CLEARANCE CAN RESULT IN POOR SPRING DYNAMICS OR VALVE CONTROL.
THIS IS IMPORTANT TO REMEMBER DUE TO THE HIGH RPM LEVELS ASSOCIATED WITH THIS ENGINES.
THIS ELEMENT IS THE LIMITING FACTOR IN HIGHER ENGINE SPEEDS. SO WHEN YOU PURCHASE SPRINGS MAKE SURE YOU FOLLOW THE INSTALLED SPRING HEIGHT AND LOAD PRESSURES AND MATCHING THIS TO THE VALVE LIFT FIGURES.
CHECK THE SPECIFICATIONS & COMPARE BEFORE INSTALLING!
Many times when a valve job is performed resulting in a "sunken" valve seat will skew your spring installed height. Failure to correct for this discrepancies with shims will result in poor spring performance in controlling valve motion. Some blame towards spring manufacturer is sometimes more in the installation rather than the product itself....
DAMPNER VS. NON-DAMPNER
DAMPNER SPRINGS ARE MORE "DYNAMICALLY" STABLE!
ON THE MINUS SIDE THEY ARE HEAVIER & PROMOTE MORE INTERNAL FRICTIONAL LOSSES.
RETAINER & BASE WASHER FIT:
SHOULD BE LINE TO LINE OR "SNAP" FIT.
-INTERFERENCE FIT BETWEEN SPRINGS:
SHOULD NOT RATTLE WHEN SHAKEN!
INNER SPRINGS SHOULD NOT BE DISTORTED DUE TO EXCESSIVE INTERFERENCE FIT.
THERE IS ALSO A POSSIBILITY OF A POORLY ENGINEERED CAM LOBE PROFILE WITH EXCESSIVE LIFT VELOCITIES THAT WILL SURGE A VERY GOOD SPRING PACKAGE. A WELL KNOWN CAM MANUFACTURER YEARS AGO BRAG ABOUT THE POWER LEVELS THEY ARE ABLE TO PRODUCE......
THE BIG PROBLEM WAS IT BROKE VALVETRAIN PIECES AND WAS IN NO WAY THE FAULT OF THIS PRODUCTS, BUT MORE THE RADICAL CAM VELOCTIES
ASSOCIATED WITH THEIR LOBE PROFILES.....
TO BE CONTINUED.....
MANY OF US HAD VALVETRAIN FAILURES OF ONE TYPE TO ANOTHER. THE MOST COMMON IS VALVESPRING FAILURE AND ITS DESTRUCTIVE AFTERMATH.
WE WILL TRY TO ANALYZE WHAT HAPPENED AND HOW TO MAKE SENSE OF IT ALL SO WE MAY START AVOIDING AND REPEATING THIS COSTLY MISTAKE!
"NORMAL" FATIGUE FAILURES OCCUR 1.5 TO 2 COILS FROM EITHER END OF SPRING!
-THIS IS THE AREA THAT SEES THE HIGHEST STRESSES FOR MOST RACING VALVESPRINGS>
THE ENDS OF THE SPRINGS!
The center portion of the spring "surges independently" from the end causing the transition area to be the most susceptible to failure....
SPRINGS THAT EXHIBIT FAILURE "NEARER THE CENTER" OF THE SPRING ARE THE RESULT USUALLY FROM DEFECTIVE QUALITY OR AN EXTERNAL PROBLEM.
SPRING LOAD VS. LIFT VS. COIL BIND:
-BE SURE TO INSTALL YOUR SPRINGS TO MAXIMIZE DISTANCE TO "COIL BIND" ( solid stacking of the coils )
WHILE AT THE SAME TIME PROVIDE FOR ENOUGH SPRING LOAD TO CONTROL THE VALVE.
USUALLY THE HEAVIER INTAKE VALVE WHICH WILL FLOAT/LOSE CONTROL MUCH FASTER THAN THE LIGHTER AND SMALLER EXHAUST VALVE.
THE ONE EXCEPTION IS WHEN THE EXHAUST LOBE PROFILE "ABRUPTLY" SLAMS SHUT THE EXHAUST VALVE CAUSING IT TO LOSE "TRAPPED" AND VALUABLE COMPRESSION PRESSURES AT THE END OF THE OVERLAP CYCLE.
-GENERALLY SPRINGS LOSE LESS LOAD THE FURTHER THEY ARE OPERATED FROM COIL BIND.
-"OSCILLATING" STRESS RANGE HAS THE GREATEST EFFECT ON FAILURES COMPARED TO THE AMOUNT OF SPRING LOAD!
EX. Spring installed @ 1.850 @ a max lift of .600
Spring installed @ 1.875 @ a max lift of .625
Adding .025 to the installed height at the same time adding .025 to the lift sounds ok but will increase the probability of "oscillating" stresses that will kill or damage the valvespring.....
Make sure you adhere to the installed spring height recommended and with the correct valve lift range designed into the spring package.
* ADVANCED VALVESPRING MANUFACTURERS USE A SPIN FIXTURE SIMILAR TO A "SPINTRON" MACHINE TO TEST WHICH SEVERAL SPRING OR SPRING COMBINATION WITH OR WITHOUT SPRING DAMPENERS TO SEE & EVALUATE WHICH ARE THE MOST "STABLE" OF ALL SPRING TYPES.
THINGS TO REMEMBER:
IN GENERAL LIGHTER AND STIFFER COMPONENTS IMPROVE DYNAMICS AND STABILITY.
VALVESPRINGS WITH HIGH SPRING RATES (STIFFNESS) ARE LIGHTER AND GENERALLY PERFORM BETTER.
DRAWBACKS TO THIS IS THE HIGHER OSCILLATING STRESSES EQUATE TO A RISE IN FAILURE RATES.
THE NEED THEREFORE IS TO MAXIMIZE SPRING RATE WITHOUT BEING TO CLOSE TO THE DANGER ZONE.
COIL BIND:
MINIMUM DISTANCE BETWEEN COILS IS .010 x NUMBER OF COILS.
6 COILS =.060 CLEARANCE
PUSHRODS APPLICATIONS OPERATE AT LARGER .070 TO .120 RANGE.
DOHC- SOHC ENGINES:
DIRECT ACTING OR SOHC/DOHC USUALLY OPERATE CLOSE TO COIL BIND TO PROMOTE "DAMPING" OF SPRING SURGE!
ALLOWING TOO MUCH CLEARANCE CAN RESULT IN POOR SPRING DYNAMICS OR VALVE CONTROL.
THIS IS IMPORTANT TO REMEMBER DUE TO THE HIGH RPM LEVELS ASSOCIATED WITH THIS ENGINES.
THIS ELEMENT IS THE LIMITING FACTOR IN HIGHER ENGINE SPEEDS. SO WHEN YOU PURCHASE SPRINGS MAKE SURE YOU FOLLOW THE INSTALLED SPRING HEIGHT AND LOAD PRESSURES AND MATCHING THIS TO THE VALVE LIFT FIGURES.
CHECK THE SPECIFICATIONS & COMPARE BEFORE INSTALLING!
Many times when a valve job is performed resulting in a "sunken" valve seat will skew your spring installed height. Failure to correct for this discrepancies with shims will result in poor spring performance in controlling valve motion. Some blame towards spring manufacturer is sometimes more in the installation rather than the product itself....
DAMPNER VS. NON-DAMPNER
DAMPNER SPRINGS ARE MORE "DYNAMICALLY" STABLE!
ON THE MINUS SIDE THEY ARE HEAVIER & PROMOTE MORE INTERNAL FRICTIONAL LOSSES.
RETAINER & BASE WASHER FIT:
SHOULD BE LINE TO LINE OR "SNAP" FIT.
-INTERFERENCE FIT BETWEEN SPRINGS:
SHOULD NOT RATTLE WHEN SHAKEN!
INNER SPRINGS SHOULD NOT BE DISTORTED DUE TO EXCESSIVE INTERFERENCE FIT.
THERE IS ALSO A POSSIBILITY OF A POORLY ENGINEERED CAM LOBE PROFILE WITH EXCESSIVE LIFT VELOCITIES THAT WILL SURGE A VERY GOOD SPRING PACKAGE. A WELL KNOWN CAM MANUFACTURER YEARS AGO BRAG ABOUT THE POWER LEVELS THEY ARE ABLE TO PRODUCE......
THE BIG PROBLEM WAS IT BROKE VALVETRAIN PIECES AND WAS IN NO WAY THE FAULT OF THIS PRODUCTS, BUT MORE THE RADICAL CAM VELOCTIES
ASSOCIATED WITH THEIR LOBE PROFILES.....
TO BE CONTINUED.....
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