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Re: U-20 timing chain

To: Amy & Erik <erikandamy@integraonline.com>, datsun-roadsters@autox.team.net
Subject: Re: U-20 timing chain
From: Vicki Burrows <gregnvicki@earthlink.net>
Date: Mon, 22 Apr 2002 20:28:43 -0700
Shimming the tensioner is, to my understanding, primarily to make sure that the
chain does not go too slack when the oil pressure is at zero (like when you
start the car).  The tensioner is fed oil pressure to push the tensioner out
(along with the spring).  The chain can jump when you are first starting the
car if 1) the tensioner is too slack, 2) the chain has stretched over the years
and the tensioner cannot keep up 3) oil pressure is not building fast enough to
push the tensioner.  Make sure you run 20/50 oil, and also check to make sure
that the 3-4 inch tube that fits inside your oil filter is there... many are
not, and that means that the engine has to fill the filter first before sending
oil to critical places like the tensioner, cam, etc., which can leave your
chain flapping.  The L bracket is a somewhat different issue, as when the chain
gets slack it starts hitting the bracket and notching it, leading it to
fracture and come flying out of your valve cover.. whoopee!  Personally, I just
cut mine off, and use a wooden dowel that fits under the chain and keeps it up
like on an L-series engine.  If yours is not nicked, then don't worry about it,
but always check it when you adjust the valves.  If it is easy to change the
chain, I would go ahead and do it.  However, that would likely require pulling
the head as well, so you are into a head gasket, manifold gasket, head bolts
(maybe), etc etc.
Greg Burrows
67 2000


Amy & Erik wrote:

> Following Gordon's chain test (car in gear, push backwards until chain is
> slack) I can push the chain into the L bracket pretty easily.  My tensioner
> is shimmed a bit.  How much shimming is really max before things get ugly?
> Would removing the L buy me time?
>
> Would it make any sense to just replace the chains at this point?  I have a
> baby due in a few weeks, so doing the whole set up is out of the question
> for this summer ($$$$), but the whole font end of my car is off  for the
> steering replacement, so it would be convienent to do the chains now.
>
> The engine is not original in my car so I don't know its mileage.
>
> Any advice is appreciated.
> Erik Smeby
> ( I will update my site later tonight with picts if you are interested.)
> http://www.geocities.com/smedly_whiplash/
>
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