Valve float?

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70MC
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Valve float?

Post by 70MC » Mon Apr 18, 2005 9:36 am

Do i have a valve float or bounce proublem? When i disassembled my cylinder heads i was looking at my valve stem tips to see if i had my geometry correct, well i could not see a good whitness mark because my valves apparently were rotating. On a few valves i could see many whitness marks, on most valves i could see none since they looked as though they were spinning more. I have never seen this before and didn't know what to make of it. I have a sbc with Brodix T1 heads and Ferrea 6000 series valves, Comp Cams custom ground mechanical roller 268in-278ex.@.050 - .650in-.650ex net lift. I am using Comp Cams pacaloy spring #943, with an instaled height of 1.910 and 230#s seat and 570#s at 1.250. These springs have a season on them and the pressures i gave are what they are now, the pressure new at 1.250 is listed as being 598#s, if my memory serves me right (i could not find my notes) they were less than 598#s new. The valvetrain parts that i have changed is the new cam listed above that has 2 degrees more at .050 in.&ex. and .015 less lift, and .050 longer pushrods, since this new cam has a different base circle. I am shifting at 7500rpms which has not changed. I am using the titanium retainer and spring locater recomended for for this spring. Any thoughts or recomendations?
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ChrisU
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Post by ChrisU » Mon Apr 18, 2005 9:50 am

Take a look at the outer surfaces of the keepers. If it's wearing hard on the retainer, the valves are bouncing on the seats.
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PRH

Post by PRH » Mon Apr 18, 2005 8:21 pm

what are the lobe numbers of the new cam you're running??

70MC
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Post by 70MC » Mon Apr 18, 2005 11:53 pm

ChrisU, I don't see any unusual wear on the keepers or retainers.

PRH, the lobe lift is .421in. and .421ex., i am using 1.6 rockers on both in. and ex. also.
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Valve float

Post by Adger Smith » Tue Apr 19, 2005 7:44 am

70mc Try reading this:

http://www.manleyperformance.com/mtr.html

Click on: Tech Report

There is some very informative reading on line about valve float & failure.
Their catalogue has a section with real nice closeup pictures.
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70MC
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Post by 70MC » Tue Apr 19, 2005 10:13 am

Adger Smith thank you for the info. The info stated by Ted Tunnecliff, "the implications are that poor rotation can cause seat leakage and guttering or excessive rotation can add to a seat face wear problem". So if i understand Mr Tunnecliff correctly he does not veiw it as a problem. My Manley cataluge from the year 2000 has a valve train trouble shooting guide in it, on page 147 it is showing, multiple rocker pattern and says "Since this type of valve train is non-rotating by design, the only way the valve can rotate is if it experiences float." When i first seen this type of pattern on my valve tips i did not know what to think until i came across this in Manleys cataluge and it made me worry. The info provided by you was written by someone who seems to know alot about valves so i am tending to believe his info and it is more up to date. I would like to get more professinal opinions, if i indeed have a problem i would like to correct it. Again thanks to everyone for replying.
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