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Old 12-09-2002, 05:34 PM
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Post single or double groove valves

Which is better, single or double groove valves for stock street heads? The old valves are double grooved with "O" ring type seals.
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Old 12-09-2002, 05:52 PM
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the o-ring seals are no lomger used on chevy engines, thus the second groove has been eliminated. if you are going to try to use the olf fashioned seal use a two groove. if you have a modern hi-perf engine with positive seals and good tight guides use the single groove. on a street engine the strength factor doesn't matter, most valves fail in the radius of the head anyway.
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Old 12-09-2002, 06:04 PM
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As long as you have the things apart, why not have them cut for PC's? Or am I way too old?
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Old 12-09-2002, 06:15 PM
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Ok, you lost me. What are PC's?? I know they are personal computers, so don't even go there! LOL
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Old 12-09-2002, 06:28 PM
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Well I am not sure, but I think he is referring to perfect circle guide seals. Am I wrong or am I wrong? GlennK
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Old 12-09-2002, 06:32 PM
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Also, while everything is apart, how can you tell if it has hardened seats? The casting date looks like 1 2 7 1 or I 2 7 1. Can't really tell.

[ December 09, 2002: Message edited by: stfinney ]</p>
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Old 12-09-2002, 07:09 PM
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Whether they are factory seats or not, they look like they are in great shape. What would blending the bowls do for performance and what is it exactly? I have heard people mention it.
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Old 12-09-2002, 07:32 PM
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blending the bowls means cutting out the casting and machining abnormalities in the bowl under the valve. P.C.s are teflon seals made by Perfect Circle, they require that the guides be cut for install. This is an old solution for oil controll and there are much better materials out there that modern seals are made from and you don't have to cut the guides for them. use the blue fel-pro seals available since about 85.
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Old 12-09-2002, 08:29 PM
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Blue umbrella seals are the best, they allow enough lubrication to the valve and don't get hard and fall off. I don't use anything else for a street engine, I've seen the perfect circle type cause galling on the valve stem due to insufficient lubrication...that never happens with umbrella seals.

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