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Discussion Starter #1
Hey guys, having an issue with a set of sbc vic jrs. Went to clean and assemble a set of rather fresh (less than 50 passes) set of heads, and noticed that the valve seats on about 5 or 6 of the holes were really pitted... none of the intake seats have a spec of rust on them. The vehicle has never really sat for any period of time, and for storage it has been in a heated shop (70deg +) with low humidity ... We run c-16 fuel, and it is a nitrous deal. Any ideas? weird that its only the exhausts. Thanks
 

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Hey guys, having an issue with a set of sbc vic jrs. Went to clean and assemble a set of rather fresh (less than 50 passes) set of heads, and noticed that the valve seats on about 5 or 6 of the holes were really pitted... none of the intake seats have a spec of rust on them. The vehicle has never really sat for any period of time, and for storage it has been in a heated shop (70deg +) with low humidity ... We run c-16 fuel, and it is a nitrous deal. Any ideas? weird that its only the exhausts. Thanks
how much seat margin ? could be over heating the valve and micro welding, seen it in turbos cars a time or 2 when there isn't enough heat dispation by the valve seat and the valve micro welds
 

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Discussion Starter #4
I hear ya with the fogging oil idea... may be the best solution! I don't think there is any micro welding going on, I see no signs on the valves themselves to indicate that.... I just find it weird that it's just the exhaust seat itself... the heads are "out of the box" stock, I'll check the margin when I get a chance... Thanks for the ideas!
 

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I hear ya with the fogging oil idea... may be the best solution! I don't think there is any micro welding going on, I see no signs on the valves themselves to indicate that.... I just find it weird that it's just the exhaust seat itself... the heads are "out of the box" stock, I'll check the margin when I get a chance... Thanks for the ideas!
look for peppering on just the seat margin, it can be hard to see. Many all in valvejobs just don't have enough valve margin to cool the valve, and frequently the valves need time to cool after a run. If they don't, shutting down the engine hot can cuase them to microfuse where there is carbon.
 

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Had the same problem with my AFR 210's. Turns out it was water if the fuel. bought new fuel!
 
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