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Re: Fitting new jets and needles

To: <spitfires@autox.team.net>, <Gosling_Richard_B@perkins.com>
Subject: Re: Fitting new jets and needles
From: "Nolan Penney" <npenney@mde.state.md.us>
Date: Fri, 01 Jun 2001 07:13:12 -0400
Yes it's important to center the jet, and yes it's easy to detect.  

The best way is to remove the air filter cover, reach in with your finger and 
lift the piston, let it drop.  It should fall all the way down, with a solid 
"clop" sound when it hits the bottom.  If the jet is off center, the needle 
will make contact and slow the piston down on its decent, sometimes even 
stopping the piston from falling all the way down.

You can also tell by running the car.  Since the piston will not be fully down 
at idle, the engine will tend to run poorly at idle, while being fine at higher 
throttle openings.  The more off center the jet, the higher it will hold the 
piston, and the worse the problem.

Centering the jet is a fundamental part of doing the carburetors.  So 
fundamental that I wouldn't be overly worried about the shop not doing this.  
They are far more likely to not get the carbs in proper synch or have the 
mixtures set optimally.  Basically, if the car runs well through its range when 
you pick it up, it's probably done right, or right enough at least.

>>> Richard B Gosling <Gosling_Richard_B@perkins.com> 06/01 3:59 AM >>>
 How can I check they have done the
 job properly?  I have heard that it is important (and tricky) that the jet is
 centred - is there some easy way I can check they've done this right?

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