I have been watching the past few days as some "dissed" the u-20 design and
they are, to a certain degree, correct. Perhaps the L design is better, but
having had several 240's they are also prone to chain stretch among other
things.
Upon examining the problem, Jim Tyler is correct, putting stuff together
fast, (guilty), Bubba's, machine shop, and running the stew out of 'em all
lead to problems. But looking at the U chain problem from the perspective of
my Cosworth headed 2.3-16 Mercedes, they found a very simple solution to the
pump-up tensioner problem. On cold starts, my MB had the "death rattle" as
the po never updated the tensioner. I went to my buddies shop, we got a new
chain and the updated tensioner, hooked the old chain to the new one,
manually rolled the engine over to put the new chain in position, installed
it with the MB chain tool and screwed the tensioner in place. The tensioner
has a ratchet that is spring loaded, you click it to hold the chain tight,
and as it slackens, the spring clicks it tighter. Works great and this thing
runs at 7,000 all day long, with 175,000 miles on the clock. A rather
inelegant solution to a bad problem.
This engine has a really long, single row skinny chain, running two cams with
solid cam followers. Works great.
Well, the Nissan engineers could have done this, but didn't for whatever
reason. Maybe technology just wasn't there thirty+ years ago. But, isn't this
the crux of our problem, borrowed technology and old age design. We were not
doing alot of things 30years ago, color tv, hardly, radial tyres, I think not.
So, the reason we are all here is our affection for things of yore, the
frustration, bleeding knuckles, and sputtering far from home. We are all in
this for our passions, wherever we place them. If we didn't love it, we all
would drive V-TEC Hondas or something similar.
To our roadster engineers, find us a stronger chain and make us a ratchet
type tensioner!
Looks like my .20 worth.
John Brasfield
|