I am the proud new owner of a not-so-new datsun 280z Repairs are under way, but i seem to have hit a bit of a snag..... The cam drive has been taken off and now the tightening chain is slack.... would anyone happen to know a trick for tightening it w/o taking off the front engine cover??? eternal grattitude for any info

Are you saying the timing chain tensioner has popped out ? If you are there is no other way to get it back in without removing the front cover. If everything is ok and all you want to do is tighten the bolt just put the trans in fourth gear, chock the tires and torque the cam sprocket bolt to 130 ft-lbs.

Good news, bad news. The bad news is that it sounds like you didn't wedge the chain prior to removing the camshaft sprocket. The good news is that one generally only does that once. See this old post for an explaination of the wedge. Click on the link in the upper right hand corner of the post to see the entire thread:

http://www.classiczcars.com/forums/showpost.php?p=170619&postcount=8