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Valve Spring Reference
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<blockquote data-quote="Deleted member 3831" data-source="post: 92071"><p>David,</p><p>the Gold Star springs referred to need to be identified by maker and part number before any sensible comment is possible, likewise the beehive springs latterly mentioned. The details released by spring manufacturers permits a reasonable guess as to the possibliity of fitting, but little else.</p><p>Spring rates and seated poundages can have little or no relationship to the valve train or the cam profile, and in a high performance application it is essential to know the natural harmonic frequency of the spring (s).], something that is impossible to establish- from the manufacturers data tables.</p><p>If the Gold Star springs mentioned are from the same manufacturer who supplied springs to Eddie Dow for his BSA Gold Stars, they were from S and W springs in the USA (Sparks and Witham). Both Art Sparks and Tim Witham are long deceased, but the company continues as RD Springs. </p><p>Why would one want to discover the natural harmonic frequancy of the spring(s) ?</p><p>Because if this frequency should happen to coincide with that of the engine at a particular engine speed, serious oscillation can occur within the spring coils, resulting in loss of control of the valve train, and even component failure if the situation persists. Now add the natural harmonic frequency of the pushrods into the mix, and the end result could be trouble with a big T !</p><p>To avoid such a situation, the general tactic is to select components whose natural harmonic frequencies are outside of the engines normal operating range, but selecting springs from a manufactures list one can only hope that the spring chosen will do the job, and not bring with it any problems of the above mentioned kind.</p><p>Phil,</p><p> the big single that finished the Classic TT with beehive springs, would you enlighten us a little and reveal what the engine was ?</p></blockquote><p></p>
[QUOTE="Deleted member 3831, post: 92071"] David, the Gold Star springs referred to need to be identified by maker and part number before any sensible comment is possible, likewise the beehive springs latterly mentioned. The details released by spring manufacturers permits a reasonable guess as to the possibliity of fitting, but little else. Spring rates and seated poundages can have little or no relationship to the valve train or the cam profile, and in a high performance application it is essential to know the natural harmonic frequency of the spring (s).], something that is impossible to establish- from the manufacturers data tables. If the Gold Star springs mentioned are from the same manufacturer who supplied springs to Eddie Dow for his BSA Gold Stars, they were from S and W springs in the USA (Sparks and Witham). Both Art Sparks and Tim Witham are long deceased, but the company continues as RD Springs. Why would one want to discover the natural harmonic frequancy of the spring(s) ? Because if this frequency should happen to coincide with that of the engine at a particular engine speed, serious oscillation can occur within the spring coils, resulting in loss of control of the valve train, and even component failure if the situation persists. Now add the natural harmonic frequency of the pushrods into the mix, and the end result could be trouble with a big T ! To avoid such a situation, the general tactic is to select components whose natural harmonic frequencies are outside of the engines normal operating range, but selecting springs from a manufactures list one can only hope that the spring chosen will do the job, and not bring with it any problems of the above mentioned kind. Phil, the big single that finished the Classic TT with beehive springs, would you enlighten us a little and reveal what the engine was ? [/QUOTE]
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Valve Spring Reference
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