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Calculating valve spring sizes

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vintagengineer	01/09/2023 12:19:11
469 forum posts 6 photos	I am building GN cycle car engine with some OHV heads. I am stuck on how to calculate the valve spring length and poundage?
HOWARDT	01/09/2023 12:41:10
1081 forum posts 39 photos	Is the force you need for the spring or the spring details? Spring manufacturers have online calculators these days but I use an old book which relates wire diameter to spring force in a table, so quite easy to look up with a quick calculation.
Roderick Jenkins	01/09/2023 13:24:20
2376 forum posts 800 photos	If you are trying to determine the spring force that you need to keep the cam follower in contact with the cam then you need to know the weight of the valve gear being moved and the acceleration due to the cam at the maximum speed of the engine - Force = Mass x Acceleration. If the cam has a flat follower than CamCalc can help give a figure for the theoretical maximum acceleration which will act as a starting point for determining the correct spring size. CamCalc dropbox link Rod
duncan webster	01/09/2023 15:07:00
5307 forum posts 83 photos	Should you add half the mass of the spring as well? Make a guess in the first place as the design isn't fixed
john halfpenny	01/09/2023 18:44:18
314 forum posts 28 photos	Why not look at similar vintage engines?

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