PhaTTy Posted March 30, 2004 Share Posted March 30, 2004 I have my head (I believe its a N47 or P79) at a machine shop. While it is there I am wondering how much I should have it milled. I have researched on here and seen most people are doing theirs 80 thousands or so. Everything else in the block/head is stock and this is a N/A car. What could I expect the CR to be and will everything clear if I do 80 thousands. Any recommendations/comments are welcome Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 30, 2004 Share Posted March 30, 2004 I think the P79 has the same chambers as the P90. If that is the case, then this site has good info: http://geocities.com/zgarage2001/p90.html Basically you just mill .080, run the .080 longer valves from a 280Z, then shim the cam tower .080, and get 10:1 compression. Don't even need to change the lash pads! Not sure on the N47. Is that the same as the N42, but with exhaust liners? If so, I'd say find a P90 and do it right. Jon Quote Link to comment Share on other sites More sharing options...
PhaTTy Posted March 30, 2004 Author Share Posted March 30, 2004 It is the P79 head that I have. Is there an easier way than putting longer valves and shimming the cam tower? Edit - talked to my brother and we thought maybe a N42 or N47 head would be a lot cheaper to get and maybe shave it .020 instead of messing with this P79 head. Let me know how this sounds. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 30, 2004 Share Posted March 30, 2004 It really doesn't get any easier than that when it comes to increasing compression. The shims are cheap and easy to install, and you can buy an old N47 for $50 and take the valves assuming they're in good shape. You could try the Z22 slack side chain guide as someone else suggested (DAW or Lockjaw I think) and not shim the cam towers, but then you'd have to switch out all the lash pads, which is not hard but is time consuming and ~$5 or $6 per pad IIRC and you kind of test fit until you find the right ones unless your machinist has some (not likely) so you might have to buy 4 or 5 sets, and your cam timing is also off at that point (not sure of when that will start to affect valve/piston interference). Either way gets it done, but I'd shim the towers and get longer valves. You can also just have the machine shop order 280Z valves if that's easier. Jon Quote Link to comment Share on other sites More sharing options...
PhaTTy Posted March 30, 2004 Author Share Posted March 30, 2004 So basically it would just be easier to get a N42/N47 head and have it shimmed? If so, how much could/should I have it shimmed. Sorry for all the questions, but I want to get this right Quote Link to comment Share on other sites More sharing options...
DAW Posted March 30, 2004 Share Posted March 30, 2004 Which shortblock are you using, L28 with dished-top pistons or flat-tops? If you have flat-tops and want to keep the project simple and inexpensive, just use the N42/47 L28E head and shave it the minimal amount to true it and you'll end up with what you want. DAW Quote Link to comment Share on other sites More sharing options...
PhaTTy Posted March 30, 2004 Author Share Posted March 30, 2004 i am using dished pistons. I called the machine shop to put the P79 on hold while I try to get ahold of a N42. Thx for all the help. Quote Link to comment Share on other sites More sharing options...
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