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Re: Carbs

To: "William T Snyder, II" <wtsnyder@juno.com>
Subject: Re: Carbs
From: David Councill <dcouncil@imt.net>
Date: Sun, 01 Jul 2001 21:44:16 -0600
I think your jets are too low and you are running rich (as if the choke was 
on). And now for a possibly related story of my personal experience.

The first time I rebuilt a set of SU carbs was in college on my first MG, a 
65B. Car started fine but once it warmed up, the car wouldn't start. Had to 
tow it to a nearby Foreign Auto repair shop. They fixed it - said I had put 
the jets in wrong, they were too low, so it was like having the choke on. 
How I did that, I never knew, but I took their word for it.

Twenty years later.... I hand my son a pair of SU carbs for his 65B plus 
the carb kits and I said rebuild this. The next day, I checked his 
handiwork out. First thing I noticed was that the jet-adjusting nuts looked 
correct but the jets were not flush with the nut, they were just a bit 
lower (showing the inner brass part). Thus any adjustments of those nuts 
would have no bearing on the fuel mixture. The problem was with the metal 
piece that screws on the bottom of the jet, this piece attaches to the 
choke linkage to give its downward motion. He had it on the wrong side of 
the jet thus pushing it down too far. This metal part should attach to the 
float side of the jet with a small round distance piece in between. So I 
figured he duplicated my earlier mistake!

If this isn't clear, I can take a few pictures. I fixed the one carb but 
the other is still the wrong way. My son hasn't finished the job but then 
we are waiting for some linkage pieces from another lister before we put 
the carbs on the car (replacing a set of HIF carbs).

David

At 10:20 PM 7/1/01 -0400, you wrote:
>Hello list. I have a '66B with an earlier 3-main engine fitted with
>original SU carbs. I recently tried fiddling with the rich/lean
>adjustment using an SU synchronizer tool. I now have the car running best
>with both jet-adjusting nuts fully tightened and I still don't have full
>synchronization. The car starts well (please don't strike me, Prince of
>Darkness!).
>
>Does this mean that I need new needles? If so, how do I determine which
>type, and where does one start to retune from scratch? What signs
>determine that the carbs are in need of a complete rebuild, and is this a
>job to be attempted by a neophyte (i.e. me)?
>
>Thanks in advance for your answers.
>Bill Snyder
>'66MGB
>'72BGT

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