I'm looking for a set of new exhaust valves for my 52 9430 GMC. The valves in it have a depression on the bottom where the set I see on Ebay are flat bottom. They are Thompson S1867. Does anyone know if the depression matters? Possible compression difference?

Mark

Last edited by 52_Ton; 08/28/2014 12:51 AM.
1952 GMC 9430 one ton pickup, a work in progress

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