zbigtim Posted December 26, 2008 Share Posted December 26, 2008 Just a quick question. I'm planning on sending my used P90 head to the local machine shop w/ the valves out of my N47 head. Will they work? It seems like I read somewhere that the valve stems were longer on the N47. Is that right? Quote Link to comment Share on other sites More sharing options...
theghosttanker Posted December 26, 2008 Share Posted December 26, 2008 The valve stems are .080 longer in the n-47 head. These valves are used in p-90 heads by folks who are doing the head shave/cam tower shim modification that is very popular with p-79 or p-90 heads: the head is shaved 080 to raise the compression ratio, the cam towers are shimmed up 075 to keep timing chain tension correct,, and the long-stemmed n47 valves are used to keep the lash pad thickness and cam lobe wipe patterns correct. If you are planning to use your head for an NA build then this is a great option but if you are building a turbo motor or an NA motor with an unshaved head then no, you don't want to use these valves. If you Google SI valves you will find that high quality brand new undercut swirl polished valves are not that expensive. Quote Link to comment Share on other sites More sharing options...
zbigtim Posted December 26, 2008 Author Share Posted December 26, 2008 Yes, thank you, I am doing a turbo build. I will check out the SI valves. Quote Link to comment Share on other sites More sharing options...
caen fred Posted January 16, 2009 Share Posted January 16, 2009 What if you shave the P90 shim the towers but keep the P90 valves? Quote Link to comment Share on other sites More sharing options...
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