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Re: Weber Carb question 2003 08:09:50 -0800 (PST)

To: FUZZY95687@yahoo.com (Larry Pitts)
Subject: Re: Weber Carb question 2003 08:09:50 -0800 (PST)
Date: Wed, 12 Mar 2003 20:08:47 -0500 (EST)
Cc: spridgets@autox.team.net
Hi, Larry...

Since the 33mm choke is undersized for
a 45DCDOE (the 1275's 34 is even a little
small for the "45", placing the stock 1275 more toward "40" than "45"
territory, though either is used successfully)
so I wonder what a 33 is doing in
there to begin with. My guess would be
somebody was trying to "bring up" the low
rpm range  as in "street torque" but this
is pure guesswork.... 

...a 55 pump jet with a 33 choke...very
strange..."feels" out of "proportion" to
me. Large pump jet....small choke?

F15 is not an emulsion tube normally found in British sports cars of
siamesed
port design. Usually F16's with 4.5 aux.
venturies or F2's, usually with 3.5 aux.
venturies, sometimes 8/9 for the larger,
tuned engines for bottom end to eliminate
or help eliminate off-idle "bog" when using
hairier cams. Some of the English Ford's used F15's, I recall, but so
did a lot of other engines in a lot of other car's, I'm
sure! :)

So, no clue, really. I shall hunt for my 
Weber manual for "standard" MGB settings. 

The identifying number on the aux vent
can be found on the side of the "ring"
opposite the fuel feed hole, just above
the "locating hole" (which isn't a hole!)
These numbers can be difficult to see,
being small to begin with.

Siamesed port engines usually do better
with smaller aux venturies as these bring
the main system in "sooner" (smaller
cross section) and take a little pressure
off the accelerator pump, idle and progression circuits in going from
off
idle to the main system without any
"hesitation" with hairier cams wherin
dilution of the incoming charge due to
exhaust gas "reversion" may be a factor,
especially with larger than stock valves
wherein low rpm flow velocities due to
larger port sizes may be compromised.

Let's see if I can find my Weber book. 
Maybe Phred is sleeping on it! :)




Cap'n. Bob (Ret'd)
      '60 Frog

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