Yes, Alex...
I'm not as refreshed as in exiting a shower, but I am refreshed to the
extent
necessary!! :)
Since it came off a tuned Sprite and you
are running a tuned Sprite, we know
we're in the ballpark to begin with, for sure. I don't know the S&K but
will
"ass-u-me" in accordance with your
comments on same. This would mean
it's got the same mechanical accelerator
pump apparatus and "circuit" as a DCOE
(no diaphragm as in Dellorto).
First of all, you haven't got one of
those recalled fuel pressure regulators,
right? :) Assuming you don't...
Since it came off a Sprite with a hot
cam and larger intake valves, the
accelerator pump circuit can reasonably
be expected to be tuned on the rich side,
relative to the cam profile and stock size
valve sizes you are running, ass-u-ming
this Sprite was a "street" rather than
"track" application and ran without "bogs"
or any other problems.
But you know the first thing that occurs
to me right off the bat is.....
what size chokes are you running? Same
size as off the "hotter" engine the carb.
came off with?
Or were they sized down for your
"milder" state of tune?
Fr'instance, this Spring I am going
to convert over to my old 45DCOE from
the stock carb. set-up that the engine
was broken in on.
I am going to try it first with the 38mm
chokes I used in my Vizardized +.060
1275 (1340?) with a flowed head and
1.414 intake valves, on my current
Cooper "S" spec. 1293 with standard valves but better flowing alum. head
&
1.5 RR's.
If it "bogs", the first thing I will do is
size down the chokes to "36"'s.
The other thing that immediately comes
to mind, is too much initial timing for
the octane used or a weak ignition circuit,
which might be fine for gentle acceleration
but breaks down a bit under load, though
the vehicle does accelerate just fine when
you put your foot in it, once at rpm. Still....
....as Peter C. is so fond of saying, most
carburator problems are electrical in
nature. I, too, have found this to be the
case many times over. It's food for thought. A weak coil, weak wire,
weak
plug, yadda, yadda, yadda! Of course, if
you've changed all these over time and
the problem has always persisted, that
would be taken into account when the
time comes to get the car out for the
coming season and we sincerely go to
work on this.
NOTE: Things to ponder in the meantime!
too much initial timing will
"dry out" the mixture on "progression"
either "on" or "off" the accelerator pump
circuit, though idle may be correctly set.
In the first case there is a definite "bog".
when you put your foot in it, off idle, and
this gets worse the further you put your
foot in it from off-idle.
In the second case (gentle acceleration
off-idle) there is "hesitation" to one extent
or another.
In the overly-rich condition: In the first case there is a definite
"bog", in the
second case there will NOT be a
hesitation on gentle acceleration.
In addition to accurately set timing, you've
got to be assured of a quality spark at
all four gaps. It is amazing how many
carb. problems are resolved in this fashion. An oscilloscope/analyzer
check
may be necessary.
Another thing to think about..determining
whether you have 3.5 or 4.5 aux. venturi's
as a "bog" can often be cured by bringing
in the main system "sooner", as in 3.5
in place of 4.5, all else being equal......
Sure, you could go with a larger pump jet
if the top end would tolerate the richness
(high rpm "bleed" from acc'l. pump circuit)
but fuel economy would suffer. So you
really don't want to go this route unless
you have to.
And, an accurately set float level. We also
have to make sure the carb. is "clean"
internally, as these carbs. are loaded with
tiny channels....unlike our SU's.
A bit of sand or grit is all you need to block fuel to one extent or
another though
this malady is usually the province of the
idle/progression circuits.
When you are ready to get the car out
and begin, let me know. I love trouble
shooting Weber problems.
Cap'n. Bob (Ret'd)
'60 Frog
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