[Mg-t] Too high idle speed

[Clive Sherriff]

Dan,

If everything else looks OK then its probably due to a leak at the Carb /
Inlet manifold joint due to the Carb flange having warped.  It's a fairly
low grade metal to say the least.  Ensure the carb flange face is flat -
usually a simple filing job, and refit with new gaskets (trust there is a
gasket!) and try again.

Clive
==================================
----- Original Message ----- 
From: "Dan" <imoz at columbus.rr.com>
To: <mg-t at autox.team.net>
Sent: Friday, September 04, 2009 3:51 AM
Subject: [Mg-t] Too high idle speed


> Listers,
>
>
>
> I have done all the homework I can, and now at wit's end, I need your
> expertise.  Sorry for the length of this request, I am trying to include 
> all
> relevant info.
>
>
>
> Though I have driven my '54 TF more than 500 miles since engine was
> partially rebuilt by a factory trained (back then) mechanic.  Top end 
> only,
> and I am not sure of each and every thing he did, but it included a good
> used stock cam, and new valve guides at least.  Each cylinder compression
> reads right around 140 psi.  Carbs were rebuilt by another veteran of
> similar vintage whose TSO ads you would be familiar with.  These gentlemen
> are well experienced, so it seems unlikely they put things back together
> wrong.  I have thus assumed the jets are properly centered (they come down
> with a "clunk" when lifted and let go).  The idle adjustment screws were 
> set
> with the connecting rod loosened so that each adjustment screw was
> independent of the other.
>
>
>
> After many tries at tuning, I finally took the car to the local LBC shop
> (which restores and maintains many British and special sports cars).  They
> corrected the timing, re-balanced the carbs and adjusted the mixture.  It
> runs much better, and after 100 miles last weekend, the plugs are light 
> tan,
> all of them.
>
>
>
> Here's the problem.  The idle speed is still 1200 - 1300 RPM and the
> adjustment screws as far out as they will go without actually removing 
> them.
>
>
>
>
> Having reviewed Mr. Old's articles on tuning from The T Series Handbook 
> (did
> my homework as best I could), I am concerned about his paragraph saying 
> the
> most likely cause of inability to adjust RPMs to the desired 800 - 900 is 
> an
> intake air leak.  I tested this with an unlit propane torch, but was 
> unable
> to perceive any change in engine speed or performance.  I am concerned
> because of Mr. Old's admonition that with an intake leak the car might 
> idle
> OK, but will suffer from a wrong mixture as the engine is revved up under
> driving conditions.   He says that bad things can happen then.  I also
> reviewed the archives, and I really don't want to get into removing the
> newly rebuilt carbs unless I have to (Lawrie Alexander's instructions to a
> TD owner.)
>
>
>
> Is my only option to change out the intake / exhaust gasket to be sure 
> there
> is no leak?  Is there any other way to understand what is happening, or to
> make this adjustment?  Should I stop driving the car until this is solved?
> Or, should I quit worrying and drive the car with the idle at 1200 to 
> 1300?
>
>
>
>
> Any help appreciated.
>
>
>
> Dan
>
> TF Car # 3563
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