Jehannum Posted March 19, 2010 Share Posted March 19, 2010 I'm rebuilding my 240Z after it got crunched last May. I'm nearing the end game here (just have to paint the engine bay and reinstall everything), and I just got my head back from the machine shop. Initially, it was just there to have the #1 exhaust stud extracted. I had them check the straightness too, and they shaved .008" off the bottom (there was a low spot between 3 and 4). Do I need to shim the cam towers? I know it's required for > .015", but I'm hard pressed to find any shims on the market <.010" in thickness. Probably an elementary question, but searching "cam tower shim" on this site comes up with people who are milling .040" off for compression reasons more than people like me who are quite happy with a stock L24. Quote Link to comment Share on other sites More sharing options...
johnc Posted March 19, 2010 Share Posted March 19, 2010 I'm rebuilding my 240Z after it got crunched last May. I'm nearing the end game here (just have to paint the engine bay and reinstall everything), and I just got my head back from the machine shop. Initially, it was just there to have the #1 exhaust stud extracted. I had them check the straightness too, and they shaved .008" off the bottom (there was a low spot between 3 and 4). Do I need to shim the cam towers? I know it's required for > .015", but I'm hard pressed to find any shims on the market <.010" in thickness. Probably an elementary question, but searching "cam tower shim" on this site comes up with people who are milling .040" off for compression reasons more than people like me who are quite happy with a stock L24. Probably not. .008" is more clean up then a shave. Quote Link to comment Share on other sites More sharing options...
pcakes55 Posted March 20, 2010 Share Posted March 20, 2010 Not the jack your thread, but are the shims used to take up slack in the timing chain? Couldn't you just extend the tensioner? I've never heard of this so I'm curious Quote Link to comment Share on other sites More sharing options...
jasper Posted March 20, 2010 Share Posted March 20, 2010 (edited) The cut/shave, can change your cam timing... Edited March 20, 2010 by jasper Quote Link to comment Share on other sites More sharing options...
letitsnow Posted March 20, 2010 Share Posted March 20, 2010 The cut/shave, can change your cam timing... Assuming the cam is degreed properly when installed, I'm not sure exactly how this could happen. The ratio between the cam and the crank is completely independent of the length of the chain connecting them. I could understand if the tensioner couldn't take up that much slack. Quote Link to comment Share on other sites More sharing options...
jasper Posted March 20, 2010 Share Posted March 20, 2010 (edited) The lenght of the chain between the sprockets determines timing. The slack side is irrelevant. This is why Mercedes Benz makes offset keyways for their V8 cam sprockets. This enables you to degree the cam and account for/compensate for chain stretch/dimensional differences. I've used them, and done it. Think about it . The cam must rotate to take up the slack of the shaved head....... Edited March 20, 2010 by jasper Quote Link to comment Share on other sites More sharing options...
jasper Posted March 20, 2010 Share Posted March 20, 2010 http://www.google.com/products?q=offset+camshaft+keys&rls=com.microsoft:en-us:IE-SearchBox&oe=UTF-8&sourceid=ie7&rlz=1I7ADFA_en&um=1&ie=UTF-8&ei=a0SkS4_oCMKBlAfPmISaAg&sa=X&oi=product_result_group&ct=title&resnum=11&ved=0CC8QrQQwCg Quote Link to comment Share on other sites More sharing options...
letitsnow Posted March 20, 2010 Share Posted March 20, 2010 The lenght of the chain between the sprockets determines timing. The slack side is irrelevant. This is why Mercedes Benz makes offset keyways for their V8 cam sprockets. This enables you to degree the cam and account for/compensate for chain stretch/dimensional differences. I've used them, and done it. Think about it . The cam must rotate to take up the slack of the shaved head....... Those are tools for degreeing the cam, I guess I was just assuming either the factory sprocket had a hole that worked, or an adjustable sprocket. Quote Link to comment Share on other sites More sharing options...
jasper Posted March 20, 2010 Share Posted March 20, 2010 (edited) Degreeing the cam/timing the cam,......same thing. The only cars I can remember having factory adjustable cam gears were the early Jaguar L6 engines. Not an easy task. Made a big change when you got them right. Edited March 20, 2010 by jasper Quote Link to comment Share on other sites More sharing options...
roger280zx Posted March 20, 2010 Share Posted March 20, 2010 Officialy jacked! Quote Link to comment Share on other sites More sharing options...
DAW Posted March 20, 2010 Share Posted March 20, 2010 Officialy jacked! With a used chain and sprockets and a clean-up cut on the head, you may be in sprocket hole #2 to get the cam timing right. If it's a toss up between #1 and #2 holes, I recommend #2 since that is the direction that wear is going to take you. DAW Quote Link to comment Share on other sites More sharing options...
Dtsnlvrs Posted March 20, 2010 Share Posted March 20, 2010 With a used chain and sprockets and a clean-up cut on the head, you may be in sprocket hole #2 to get the cam timing right. If it's a toss up between #1 and #2 holes, I recommend #2 since that is the direction that wear is going to take you. DAW Ding Ding Ding...and common sense prevails Quote Link to comment Share on other sites More sharing options...
tightywhitey185 Posted March 21, 2010 Share Posted March 21, 2010 Im sort of in the same situation.Im sending my stuff to the shop tomorrow And ill bet it will need a deck cleaning and some pretty normal machine work.In your situation wouldnt a thicker head gasket solve this?Are there different thickness headgaskets made for these motors?I would asume yes becuase anyone who has had machine work and wants to return the motor to stock configurations would absolutely need one.On an L24 what is the max you can machine of of the deck and the head before you have to fly cut pistons or run compression too high or run into cam timing issues?what size head gaskets are available? Quote Link to comment Share on other sites More sharing options...
Jehannum Posted March 21, 2010 Author Share Posted March 21, 2010 Probably not. .008" is more clean up then a shave. Thanks! Quote Link to comment Share on other sites More sharing options...
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