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Re: Idle speed

To: craig wiper <craigw@sonic.net>
Subject: Re: Idle speed
From: ek_john_luthy <luthy@cesd.servtech.com>
Date: Mon, 27 Nov 1995 21:55:16 -0500 (EST)
On Mon, 27 Nov 1995, craig wiper wrote:

> 
> >Second question:  There is a big difference in idle speed with the clutch
> >engaged or disengaged.  The engine idles faster with the clutch engaged
> >(tranny turning in neutral) and much slower with the clutch disengaged (pedal
> >down).  This seems backwards to me since the engine has to turn the tranny
> >with the clutch engaged in neutral.  Why does this happen?  or  Why am I
> >confused?
> >
> >Thanks for any advice.
> >
> >Keith Baer
> 
> When the clutch pedal is depressed, the throw-out bearing is pressing on the
> pressure plate of the clutch, holding it off of the clutch, which results in
> resistance to the engine, similar (sort of) to a break-pad being applied to
> a rotor . Hence, the engine slows a bit. When the engine and transmission
> are connected but in neutral, everything is free to spin with less
> resistance. Does this make sense?
> 
> Craig Wiper
> early '74 MGB
> 
> 
        I don't know why I want to join this thread but.... I read in an 
shop manual (i don't rember what one) that the idle speed should be set 
with the clutch pedal depressed.        
        I have tuned up and repaired thousands of cars and have spent hundreds 
of hours in classes and seminars, but have yet to learn how this has an 
effect on idle speed. BTW I have watched the idle speed and depressed the 
clutch and not seen any change, should the engine be running for this 
test.:)

        John (still working on my sig. file) Luthy
        aka Lex 

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