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Re: HIF4 idle speed

To: Craig Wiper <craigw@sonic.net>
Subject: Re: HIF4 idle speed
From: "S. L. Hower" <howersl@ttown.apci.com>
Date: Sun, 9 Mar 1997 17:29:14 -0500 (EST)
On Sun, 9 Mar 1997, Craig Wiper wrote:

> Hi. Now that I've got the HIF4's on the B, that nagging high-idle speed has
> come back. Backing the idle-adjust screws all the way back doesn't help.
> The butterfly's can still be pushed by hand and closed a bit, bringing the
> idle speed down to where I like it (900rpm or so) instead of about
> 1200-1300rpm when fully warm. Does anyone have any suggestions as to how to
> keep the idle in check?
> 
  Craig,

  Have you tried fitting solid throttle plates?  The HIF4s have
  little air valves in the plates that are supposed to improve
  emissions under closed/off throttle (high manifold vacuum) 
  conditions.   It is common for the springs in these valves
  to become weak over time and allow air to pass by at idle.

  The fix is to either solder/jbweld/otherwise secure the valves
  in the plates (or the *best* fix is to install the solid plates
  from early HS4's.  

  Hope this helps.

  --Scott 

   Scott Hower  --> howersl@ttown.apci.com
   Air Products & Chemicals, Inc.
   7201 Hamilton Blvd Trexlertown, PA
   (610) 481-2646


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