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Re: [Spridgets] Confused - Weber issues (longish)

To: soavero@yahoo.com, spridgets@autox.team.net
Subject: Re: [Spridgets] Confused - Weber issues (longish)
From: Weslake1330@aol.com
Date: Mon, 2 Jun 2008 12:53:00 EDT
Hi Ron,
 
You need to start from the beginning.  All main jet sizes are fairly  
meaningless without the aux venturi size.  Also you do have the aux venturi  in 
the 
right way round and right way up don't you?
 
Has this carb ever run ok on this engine?
 
Daniel1312
 
In a message dated 02/06/2008 03:32:45 GMT Daylight Time, soavero@yahoo.com  
writes:

I'm  having issues with my Weber 45DCOE on a 1275
(street car). The carb is  mated to a 3.75" Minispares
manifold, 36mm chokes. The below is a  little
convoluted, as things that should have mattered
didn't, so I  tried some unconventional things. 

I can't get it to idle properly, it  wants to be too
high. I "mixed" it as I usually do - set the idle
speed  screw 1/2 turn off the stop, used the mixture
screws to set a smooth  running idle, then adjusted RPM
with the idle screw. I can't get the idle  below 2200
RPM without backfiring and spitting out the velocity
stacks,  even after finding the aux vent screw
replaced. Timing is fine. Valves were  fine. No
discernible intake leaks. Replaced points, plugs,
coil, wires,  distributor with known good. Definitely
all indications of lean. It runs  great once it's off
the progression circuit. So just for grins I upped  the
main size from 140 to 160 without changing the air
corrector. It  behaves better, I can drop the idle by
500 RPM, but still 500 shy of where  I'd like it to be.
The thing is...NONE OF THIS makes sense to me.  I
thought the mixture screws set the idle with a small
contribution from  the idle jet, and the idle jet
progression circuit takes you from idle to  about 2500
RPM, where the main circuit kicks in. **Why did
changing the  main jet help at all?** And what will
make it all better completely? When I  get back from a
drive, it reeks of gasoline and the plugs look rich.  I
only have the idle SPEED screw just barely cracked at
this point, so I  don't think I'm doing anything to the
idle progression holes. I have only  ever used F9 idle
jets on 4 diffrent Weber setups I've had on  my
Sprites, so I don't have any other sizes "in stock". I
tried that  little venturi bypass thing, it didn't do
anything.

Any opinions are  welcomed. Telling me to switch back
to SUs is obvious so I respectfully ask  that you
refrain. I have never had much trouble dialing in a
Weber  before.

Ron
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