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Re: Carburetor adjustment

To: Jorge Garcia <fortee9er@yahoo.com>, healeys@autox.team.net
Subject: Re: Carburetor adjustment
From: bspidell@comcast.net (Bob Spidell)
Date: Mon, 16 Oct 2006 20:11:54 +0000
Jorge,


Let's take a step back and approach this a little more systematically.

First off, why are you assuming the problem(s) is with the carburettors?
Are you absolutely certain that your ignition system is working perfectly?
Are you sure the fuel pump is performing properly?  Are you sure there's
no water or crud in the gas tank or elsewhere in the fuel delivery system?

If you're sure the ignition and fuel delivery are OK, check to see if a jet 
needle dropped from a vacuum piston.  Otherwise--in spite of what a lot of 
people think--SU carburettors are pretty much "set and forget" (you don't 
need to be constantly fiddling with them unless you're going through a serious
change in altitude, probably not even then).  If your car was running
fine after you set the carbs, then there's no reason for that to change
suddenly.


bs


--
***************************************************************
Bob Spidell         San Jose, CA        bspidell@comcast.net
'67 Austin-Healey 3000             '56 Austin-Healey 100M
***************************************************************

 -------------- Original message ----------------------
From: Jorge Garcia <fortee9er@yahoo.com>
>   My 1965 BJ8 would not maintain a steady idle speed after reaching operating 
> temperature and the choke was off. The engine would stumble and die while 
> waiting for a traffic light. I checked my AH Haynes manual, a couple of books 
>on 
> SU carbs and Norman Knock's Tech Tip book. I used Norman's technique for 
> adjusting the carbs, I fiddled with the idle speed and then with the idle 
> mixture screw until it idled steadily. I drove it for a few miles and it did 
> great it did not stumble while waiting for traffic lights to change. All that 
> changed Saturday when I was showing off to my son-in-law and accelerated 
>fairly 
> hard coming off a traffic light. As soon as I let off the gas I could feel 
>that 
> something had changed, the engine was not running as smooth as it had a few 
> minutes before. When I pulled to the next traffic light the engine stumled 
>and 
> wanted to die so I had to keep my foot on the gas to keep it from dying. 
>   Why would revving the engine cause the carbs to loose their adjustment? One 
> last thing, I did not perform the last step of Norm's adjutment procedure for 
> checking choke and linkage adjustment. This the one where you stick your 
>finger 
> into the carb's throtle body and check that the butterfly is fully open while 
>"a 
> friend" has his foot buired in the gas pedal with engine running at full 
>speed. 
> What is going on with my carburetors?
>    
>   Thanks
>   Jorge Garcia
>   Houston, TX
>  Everyone is raving about the  all-new Yahoo! Mail.




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