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Registered
Join Date: Feb 2003
Location: chicago
Posts: 1,077
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valve shim problem
i started assembling the heads on my 3.2 ss and found that i needed 10-14 .5mm shims to get the spring at 34.35mm installed ht. i know 2-3 shims is typical so i am really concerned with this. the valves are new stainless type and the SC heads are rebuilt by comp. engineering w/ new seats and some porting. the springs are new dougherty units with new cups and ti retainers. i am measuring from the underside of the retainer to the edge of the cup, i then measure the depth of the cup and add the 2 #s for the spring ht. i installed 1 valve and with 10 shims i'm getting 36.8mm, still not the specified 34.35mm. any ideas? am i missing something?
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12-22-2005, 02:58 PM
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Registered
Join Date: Feb 2003
Location: chicago
Posts: 1,077
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i think i may have answered my own question. according to the dougherty web site the spring ht should be 39.5mm for these springs, not the spec 34.35mm for stock springs. rough calculation say i should only need 4-5 shims. i'm not shure what i would have done if i had tried to install stock springs, maybe the retainer and cup are different for these springs. any one have an idea?
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BMW 128i 73 rsr clone - sold 68 912 project to become 911r (almost done!) |
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12-22-2005, 03:44 PM
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Registered
Join Date: Feb 2004
Location: California
Posts: 926
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Yes the retainer and spring cup are desiged for a taller installed height. My racing valve springs install at a taller height than the factory valve springs.
Hope I didnt forget the instructions in the box.
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John Dougherty Dougherty Racing Cams |
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12-22-2005, 09:26 PM
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