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Re: Start-up Procedure

To: MG T List <mg-t@autox.team.net>
Subject: Re: Start-up Procedure
From: Bullwinkle <yd3@nvc.net>
Date: Thu, 13 Oct 2005 17:38:37 -0700
<<<snip>>>
depressing the accelerator will gain you nothing.
<<<Snip>>>

Yes, and no.  When pulling out the fuel enrichment control, the throttles are 
also opened slightly.  Thus pressing the acellerator down some will make
pulling out the enrichment control easier.  It can also allow the jets to 
decend slightly further as the enrighment control's force is used only for
moving the jets and not the throttle stops.

My basic starting proceedure is.

1)  Move gear lever to neutral as the engine will spin faster.  Holding in the 
clutch puts pressure on the throw-out carbon and on the crankshaft
center thrust bearings.

2)  Turn on the ignition and wait for the carbs to fill and the fuel pump to 
settle down to it's static state of once per 15 seconds.

3)  Depress throttle slightly and pull out the enrichement control knob. (There 
is NO "choke" butterf;y plate on a SU.  The enrichment control
actually makes the jet move lower in relationship to the tapered and thinner 
fuel needle.  This makes the area for the fuel to pass through larger.)

4)  Release throttle.

5)  Pull out starter knob smartly.  As soon as the engine fires release the 
knob.

IN my experience there is a method of throttle manipulation which helps the 
engine to start when quite cold.

The SU if properly set up and has it's oil damper filled, is designed to 
enrichen the fuel mixture when the throttle is suddenly opened.  The damper
stops the sudden rise of the dashpot and needle when the throttle is opened 
significantly.  When the throttle is opened wide and the dashpot piston is
low, a greater "vacuum" is created across the jet, thus making the engine draw 
more fuel through the jet than normal.  This is equivalent to the pump
accelerator in the "normal" US carb.

Rapid opening and closing of the throttle during cranking will cause a slightly 
higher vacuum across the jet without causing the jet and dashpot
piston to rise.  Thus, in quite cold weather when I have trouble starting the 
TD, I rapidly open and close the throttle which helps the engine start
sooner.  This proceedure also helps keep the engine running until it warms up 
some to where it will run with just the throttle enrichment control
pulled out.

REgards,

Blake

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