Rick;
I noticed your address is Orlando. Maybe sometime we can get together and
have a little outing in our area - maybe get Sid from Jacksonville and any
others nearby to join in?
<()?))>
------------------------------
Blue Skies & Calm Waters,
DAFox [SRL311-04646]
Oviedo, Florida
dafox1@hotmail.com
http://albums.photopoint.com/j/AlbumIndex?u=1423840&a=10659146
----Original Message Follows----
From: "Chianese" <chianese@sprintmail.com>
Reply-To: "Chianese" <chianese@sprintmail.com>
To: <datsun-roadsters@autox.team.net>
Subject: Idle RPM problem
Date: Mon, 13 Aug 2001 22:47:21 -0400
Kim and Robert,
The fast idle speed that happens when you slow down from normal highway
driving is often caused by throttle shafts that stick to the carb body.
Closing the throttle causes a large pressure difference across the oval
shaped throttle plate. You can have 35 pounds of force pushing the throttle
shaft into the carb body. After a few years of wear and tear, the shaft and
the holes in the throttle body are no longer smooth and friction will build
up to the point where the springs can no longer close the throttle.
Reving the engine releases the pressure difference across the throttle plate
and it has a chance to close before the pressure differential is restored.
The Japanese were smart enough to put bronze bushing into the aluminum carb
body so that the shaft would not wear an oval hole into the aluminum. (I
have seen british cars that had such sloppy fits, that the air would bypass
the throttle plate. It can get bad enough that the throttle plate can start
rubbing against the bore of the carb.) Check to see if there is a lot of
play between the throttle shafts and the carburettor. (Especially
horizontally) The bushings can be replaced if you find someone that can
line bore them after they are installed.
One of the suppliers has gone to the trouble of putting needle bearings in
the carb body to support the throttle shaft instead of bronze bushings.
That is absolutely the best solution, if you can afford it.
If lubricating the cables and pivots does not solve your problem, try
squirting some lubricant onto the throttle shaft from the outside where it
passes through the body. Don't do this on a hot or running engine or you
could end up with singed eybrows. This will only work for some period of
time that can vary from months to days. Eventually you need to fix the
bushing or get stronger springs. (I had this same problem on my roadster
and on a 1978 305 Chevy V8. The Chevy dealer sold me new throttle springs
that were about 50% stronger than the originals. That's a typical GM
solution to any problem.)
Rick Chianese
Orlando, FL
SRL311-14035
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