shimming comp 921 valve springs
03-22-2009, 07:59 PM
#1
shimming comp 921 valve springs Right now my springs are setup at the recommended rate of 135 lbs on the seat and I think 380 open. How many lbs on the seat open and on the seat have people been able to get without reaching coil bind. I am running .595 lift with the cam I am running. I am experiencing valve float under boost and would like to up the spring rate as much as safely possible without buying a new spring setup. Thanks... Just wondering if people here on the boards have had experience shimming the comp 921's and what kind of pressure was achieved.
03-22-2009, 09:21 PM
#3
No I had a shop install mine. I don't know too much about how they were installed other than the specs they gave me with the heads. I am not sure if they even used shims or not? Does everyone use shims when they install a new valve spring kit or are the shims optional? I am just wondering if I can maybe shim them more for a higher spring rate to help with some valve float I am having. On average when you install a new 921 spring kit is there room for more shimming to get a higher spring rate.
03-22-2009, 09:27 PM
#4
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when installing shims it also reduces tha maximum lift there able to handle along with chaning seat pressures. my suggestion would be better springs than the 921's a dual manley or patriot spring would do you fine.
03-22-2009, 09:38 PM
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it also depends on what kind of seals you have. The stock seals from at least 99-up have the locator built into them and wont work right if you shim the springs much. You should probably try and find out your current installed height, and coil bind height so that you can find out how much you can shim the springs.
03-22-2009, 09:42 PM
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it also depends on what kind of seals you have. The stock seals from at least 99-up have the locator built into them and wont work right if you shim the springs much. You should probably try and find out your current installed height, and coil bind height so that you can find out how much you can shim the springs.
