grinding valves
02-24-2005, 05:35 PM
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grinding valves gm says not to grind the intake valves on the ls1 because the margin is to thin to grind(they do it to lighten the valve) anyone here ground the intake valves? i plan to backcut them also 
02-24-2005, 07:37 PM
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The margin on the valve can be no less then 1/32 thick or they will start to tulip.For good flow you want .050 thick margin with a back cut.Do not back cut the ex. valve as that will increase revers flow into the chamber.
02-24-2005, 08:12 PM
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The valves can be reground, I have done it many times. It is true to not back cut the truck style exhaust valve- it also flows a few cfm less if you do, Tony Mamo @ AFR proved this to me.
02-24-2005, 09:22 PM
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Are you guys just talking about grinding like a 3 angle valve job, or thinning the valve stem inside the ports, or grinding off the top of the valve stem where the rocker slides across it, or something else? I think I know what y'all are talking about, I just want to get my vocabulary straight. Thanks!
02-24-2005, 09:27 PM
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The back cut we speak of is an additional 30-33 degree cut behind the 44-45 cut that is used on the valve itself to take the ridge down smoother for more possible flow around the valve but the tulip shape of the truck style exhaust valve is already "shaped" good enough to not need any more cutting other than just a reface of the 44-45 degree cut that comes on them.
