Valve Springs - 500 vs 525
02-21-2005, 01:54 PM
#1
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Valve Springs - 500 vs 525
Over the last year I have read allot of posts regarding the 200 to 250 hr valve spring replacements on 500efi's, which I have two with 53 hrs.... it was a fun summer last year 
Question's:
Is this also true for the 525's and other Merc Blue's?
And if not what is diff between 500 and 525?
Question's:
Is this also true for the 525's and other Merc Blue's?
And if not what is diff between 500 and 525?
02-21-2005, 02:15 PM
#2
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Re: Valve Springs - 500 vs 525
It's going to be true with any engine that see sustained rpm above 4K with a hydraulic roller valvetrain. It is the nature of the beast. The hyd roller was designed to maximize power output at lower rpm. Ford realized this with the 5.0 and the hyd roller craze was on.
The inability to use adequate spring pressure (seat and open pressure) is the achillies heal of the hyd roller. Therefore in a boat application with the higher rpms the springs will finally "harmonic set" and loose both seat and open pressure.
To increase the longevity you must add more seat pressure but then the issue of the hyd valving in the lifter rears its evil head. Aftermarket lifters are then needed to accept the higher springs loads. RMbuilder is a wealth of info on what to use here since he has been on the inside of some spring and lifter testing for hyd roller vlavetrains.
Hope this helps,
Chris
The inability to use adequate spring pressure (seat and open pressure) is the achillies heal of the hyd roller. Therefore in a boat application with the higher rpms the springs will finally "harmonic set" and loose both seat and open pressure.
To increase the longevity you must add more seat pressure but then the issue of the hyd valving in the lifter rears its evil head. Aftermarket lifters are then needed to accept the higher springs loads. RMbuilder is a wealth of info on what to use here since he has been on the inside of some spring and lifter testing for hyd roller vlavetrains.
Hope this helps,
Chris
02-21-2005, 04:26 PM
#3
MarineKinetics
Platinum Member
Re: Valve Springs - 500 vs 525
Summer Heat,
Valve springs are a “read” component, similar to a spark plug, in that they contain a great deal of information relating to the operating condition of your engine. Not only are they responsible for returning the valves to their seats, they need to keep them there; a difficult task compounded by aggressive ramping and (in some cases) forced induction. In the process they are required to dampen and stabilize the harmonics created by the valve train and dissipate the resulting thermal buildup. Spring life has so many variables it’s difficult to put a cycle value on them. Because they are affected by heat, RPM (one “zing” can kill a spring), wire quality/heat treat, and camshaft profile, the degradation curve is not linear and varies greatly from application to application. Heat is generated in the spring from multiple sources. First by cycling the spring through compression and extension. Secondly the friction between the coils. Third is absorption.
I would suggest that you check your springs for current values at seat load and open load, compare that to spec and see if you are within tolerance. These figures will give you baseline references for future fatigue evaluation and alert you to other potential valve train problems. Many cam/lifter failures originate with the springs inability to maintain dynamic stability. Check springs for discoloration and/or cracks regularly. Monitoring your springs for degradation is cheap insurance. Below are links to on head spring test tools of various prices.
http://www.power-t.com/spring/pt-700.html
http://www.intercomp-racing.com/fr_springtorque.htm
http://www.intercomp-racing.com/detail.cfm?ItemID=121
http://www.jegs.com/cgi-bin/ncommerc...52&prmenbr=361
http://www.moroso.com/catalog/catego...?catcode=27105
http://www.lsmproducts.com/p3.htm
Bob
Valve springs are a “read” component, similar to a spark plug, in that they contain a great deal of information relating to the operating condition of your engine. Not only are they responsible for returning the valves to their seats, they need to keep them there; a difficult task compounded by aggressive ramping and (in some cases) forced induction. In the process they are required to dampen and stabilize the harmonics created by the valve train and dissipate the resulting thermal buildup. Spring life has so many variables it’s difficult to put a cycle value on them. Because they are affected by heat, RPM (one “zing” can kill a spring), wire quality/heat treat, and camshaft profile, the degradation curve is not linear and varies greatly from application to application. Heat is generated in the spring from multiple sources. First by cycling the spring through compression and extension. Secondly the friction between the coils. Third is absorption.
I would suggest that you check your springs for current values at seat load and open load, compare that to spec and see if you are within tolerance. These figures will give you baseline references for future fatigue evaluation and alert you to other potential valve train problems. Many cam/lifter failures originate with the springs inability to maintain dynamic stability. Check springs for discoloration and/or cracks regularly. Monitoring your springs for degradation is cheap insurance. Below are links to on head spring test tools of various prices.
http://www.power-t.com/spring/pt-700.html
http://www.intercomp-racing.com/fr_springtorque.htm
http://www.intercomp-racing.com/detail.cfm?ItemID=121
http://www.jegs.com/cgi-bin/ncommerc...52&prmenbr=361
http://www.moroso.com/catalog/catego...?catcode=27105
http://www.lsmproducts.com/p3.htm
Bob
