Sailor Bob Posted March 23, 2010 Share Posted March 23, 2010 Just went through a significant amount of trouble to locate and drag home f54 with a P90 head - was gonna go turbo, but there was too many expences. I have a set of rebuilt SUs, a header and an electronic distributer for my 73 240 L24 - so now it's gonna go on the a L28 (which will go in the 240). My question surrounds what can and cannot be done - I have the L28 in the machine shop now and based on information from good sources the P90 will work good with flat top pistons if the head is shaved .080" and the cam towers are jacked the same amount - should give me 10:1 compression. Only thing worrying me at all is that I just recieved an email from the machinist asking if the valves will clear the pistons when they are changed from dished to flat tops? Any advise or info? Thanks Rick Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 23, 2010 Share Posted March 23, 2010 Rick I was thinking about this some more. One simple suggestion: flycut the pistons. If your stuff is being machined they should be able to do that for you too. BRAAP showed me a tool to do this easily a couple years ago. Put the cutter in the valve guide, put the head on the block and cut the notch in the piston right in place. Still a good idea to check and see if it needs doing. Quote Link to comment Share on other sites More sharing options...
DAW Posted March 24, 2010 Share Posted March 24, 2010 Check the piston-to-valve clearance and you'll know. Read any HotRod magazine for discussion. DAW Quote Link to comment Share on other sites More sharing options...
DAW Posted March 24, 2010 Share Posted March 24, 2010 Rick I was thinking about this some more. One simple suggestion: flycut the pistons. If your stuff is being machined they should be able to do that for you too. BRAAP showed me a tool to do this easily a couple years ago. Put the cutter in the valve guide, put the head on the block and cut the notch in the piston right in place. Still a good idea to check and see if it needs doing. Quote Link to comment Share on other sites More sharing options...
DAW Posted March 24, 2010 Share Posted March 24, 2010 OK, so you won't have a piston-to-valve check until you've already had the machine work done on the head (BTW, did you include N42/N47 valves in your formula/solution there?...you'll need these if you cut 0.080" from the head/shim the towers)...I'd say go for it...the worst case scenario is that you have to fly-cut the pistons...and that's not the end of the world to do... DAW Quote Link to comment Share on other sites More sharing options...
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