I've seen this more than once on throttle shafts that had recently been
replaced and the bodies rebushed. When cold, examining everything showed the
throttle shafts and butterflys moved freely and returned to absolutely close
off as required. However as the engine warmed up and everything expanded
slightly the shafts bound a small bit in their new bushings. The cure is to
either remove the shafts and relieve the tolerances a bit, or one customer
continued to drive his and everything freed up perfectly in the first
thousand miles.
Another cause of this binding can be that the throttle shafts are torqueing
toward one end causing the butterfly disc to rub against one side of the
carb throat instead of being perfectly centered. This can be caused by undue
pressure being exerted on one end of the shafts due to new shafts or
intershafts that are a bit too long.
Rich
-----Original Message-----
From: healeys-bounces@autox.team.net [mailto:healeys-bounces@autox.team.net]
On Behalf Of Bob Spidell
Sent: Sunday, October 31, 2010 5:31 PM
To: healeylist
Subject: [Healeys] BN2 Throttles
Listers,
Our BN2 runs well, but we have a small problem with the carbs. We can't get
the throttles to close to the stops
consistently; i.e. when we let off the accelerator pedal the throttles don't
(usually) come all the way back to idle
position. They usually stop about 100 RPM higher than they are adjusted to
run at idle. If I press down on the shaft
levers they move slightly and run at the desired idle speed.
We went through the carbs, cleaned them well and installed new jets,
needles, gaskets, etc. The shafts turn freely, and
there's nothing in the throttle bores getting in the way. We've tried
'torquing' the coaxial springs to get more
tension, and there's no difference with the linkage attached or
not--something is preventing the throttle plates from
closing to the desired stop point.
Any suggestions?
TIA,
Bob
--
*******************************************************************
Bob Spidell San Jose, CA bspidell@comcast.net
*******************************************************************
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