turbogrill Posted April 10, 2017 Share Posted April 10, 2017 Hi, I am trying to understand how the valve and camshaft drive train works. I understand that the lash pad needs to be the correct height to get a good wipe pattern. Lash pad tickness needs to be checked if: - Cam shape is different - Valve position is changed (valve jobs) - New rockers? If I install a taller and/or stiffer spring the valve should sit in the same position right? So the lash pad thickness shouldn't have to change? Thanks Quote Link to comment Share on other sites More sharing options...
TimZ Posted April 10, 2017 Share Posted April 10, 2017 (edited) Hi, I am trying to understand how the valve and camshaft drive train works. I understand that the lash pad needs to be the correct height to get a good wipe pattern. Lash pad tickness needs to be checked if: - Cam shape is different - Valve position is changed (valve jobs) - New rockers? If I install a taller and/or stiffer spring the valve should sit in the same position right? So the lash pad thickness shouldn't have to change? Thanks The last pad rests directly on the top of the valve stem, so the spring won't have an effect on the wipe pattern. HOWEVER - if you change the spring and/or retainers, you will still have to make sure the installed height of the spring itself is correct AND that the spring doesn't bind at full lift. Edited April 10, 2017 by TimZ Quote Link to comment Share on other sites More sharing options...
turbogrill Posted April 10, 2017 Author Share Posted April 10, 2017 The last pad rests directly on the top of the valve stem, so the spring won't have an effect on the wipe pattern. HOWEVER - if you change the spring and/or retainers, you will still have to make sure the installed height of the spring itself is correct AND that the spring doesn't bind at full lift. Hmm....I get that it shouldn't bind at full lift. But not sure what you mean with correct installed height? do you mean that it should be installed so to give good seat pressure and not coil bind at full lift? appreciate the help, got all the books but there is a few pieces that aren't clear to me. Quote Link to comment Share on other sites More sharing options...
TimZ Posted April 11, 2017 Share Posted April 11, 2017 (edited) do you mean that it should be installed so to give good seat pressure and not coil bind at full lift? Yes - installed height (along with the spring rate and free length) determines the seat pressure. Once that is set you then have to make sure that the spring doesn't bind at full valve lift. Edited April 11, 2017 by TimZ Quote Link to comment Share on other sites More sharing options...
turbogrill Posted April 11, 2017 Author Share Posted April 11, 2017 Awesome thanks! Quote Link to comment Share on other sites More sharing options...
TimZ Posted April 11, 2017 Share Posted April 11, 2017 I guess it also wouldn't hurt to mention that you should check the clearance between the bottom of the valve retainer and the top of the stem seal to make sure they don't come in contact at full lift. This clearance is not guaranteed when using a higher lift cam... Quote Link to comment Share on other sites More sharing options...
turbogrill Posted April 11, 2017 Author Share Posted April 11, 2017 Good point! If that happens what do you do? Longer valve and springs? Quote Link to comment Share on other sites More sharing options...
TimZ Posted April 11, 2017 Share Posted April 11, 2017 Good point! If that happens what do you do? Longer valve and springs? I ended up finding some very low profile stem seals and then cut down the guides such that the stem seals sat as low as possible, essentially bottoming on the spring seats. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted April 12, 2017 Share Posted April 12, 2017 The ford 2.9L v6 (ranger, bronco2) stem seal is what most people use. Quote Link to comment Share on other sites More sharing options...
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