View single post by DeDub
 Posted: 03-23-2007 02:40 pm
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Joined: 04-10-2005
Location: Sebastopol, CA, California USA
Posts: 28
OK, being my first time at the "black art" of Lotus cam shims, it's obvious to me there's a fair amount I don't understand: I'm shimming an unknown, used, new-to-me motor I'm thrown in my fresh body.  I've started it, it ran fine and didn't smoke, but because it may be in there for a year or two I thought I'd better check valve adjustment.  It needed it; most exhausts were in the single high digit range.  And there were gaskets under the towers.  So I made some guesses, ordered up a bunch of shims in the 60s range and started the tedious process of learning how fast I can install and remove the exhaust tower.  I'm not known for my small, delicate hands.  All was going OK except for the last valve on the back of #4 which continued to have zero clearance no matter how small a shim I had in there.  Finally I put in the tower with NO shim there and tried to measure that way but  couldn't get 50 thou of stacked feeler gauges to bend enough to get a satisfactory measurement but it seemed to be in the high 40 range with no shim at all. 

I'm kinda stuck.  The part that's got me in a mental whirlwind is that I remember, and my notes show, that I got a 9 thou feeler gauge in there the first time I checked them, before I ever took the tower off the first time, and when there was still a gasket under there.  How could this be?  I can't imagine anything I could have done that would have *raised* the valve stem and shrunk the clearance at least 20 thou.  Visually, the stem does look higher than the adjacent and with the tower in, the bucked looks to be about 20 thou or so higher than the adjacent.  FYI, none of the valve stem heights are very similar; obviously the PO didn't have a quality valve job done at some point.  I don't want to pull the head for one lousy high valve on an engine I don't plan to have in there forever but even a 60 shim doesn't seem to have any clearance. 

Any ideas?