I have run Strombergs for three years, and Joe Alexander has run them
for six years, I think. That doesn't mean anything other than that I
have a keen interest in advancing my knowledge of the diffences in
performance between Stroms and SU's.
I made a number of measurements this afternoon using
Stromber 175 CD's and 1-3/4" SU's with the float bowl with the central
bolt and cylindrical float. What I discovered was interesting to a
technofreak like me and maybe it will interest you, too. This is a long
message so please delete NOW if you're not interested.
Chamber capacity: For purposes of the measurements, I ran the Stroms the
way I race them -- with the floats set as high as they will go and still
shut off the fuel. I set the SU float to factory spec, not knowing what
the current SU users do. Under these conditions, the Stormberg chamber
holds 31 cc and the SU 21 cc -- and this is with the carb tilted as
installed on the engine. The Strom holds 7 more cc not available to the
jet because of the tilt.
However, what happens during cornering? As an appoximation of cornering
conditions, I assumed that the fuel in the chamber is tilted at a 45
deg. angle, and measured chamber capacity with the carbs tilted 45 deg
left and 45 deg right.
Results:
Strombergs - when tilted so gas is on the RIGHT side (simulating a left
hand corner), the floats droop and never shut off the gas -- it leaks
out the jet tube. When tilted so the gas is on the LEFT side (simulating
a right hand corner) the floats shut off the gas and the chamber
contains 12 cc. This is because the pivot for the Stromberg floats is on
the right side.
S.U.'s -- when tilted so gas is on the RIGHT side (simulating a left
hand corner), the chamber contains 38 cc. When gas is on the left side
(simulating a right hand corner) the chamber contains 31 cc. Under both
conditions, the float and needle valve shut off the fuel.
End of data.
I've tried to present just data without comments so now here comes some
real world experience. In the Alexander and Drews cars, we do not
experience the deterioration of performance in right hand corners that
the above measurements would seem to predict. The data above would
indicate that the engine should starve but it doesn't seem to. When
exiting a left hand corner, specifically #5 at RA, the Drews car
sputters but the Alexander car does not. The Drewses have attributed
this to other factors but maybe it's excess fuel.
I would expect the same situation of shutting off or flooding to be true
of any carburetor with side-pivoting floats, wouldn't you?
And finally, this all confirms what Hero Drivers the Alexanders and
Drewses are, to be running so fast with carburetors that don't
work.........just wait till next season.....
--
uncle jack
61 TR4 Rallye Replica Racer
Diligently Engineering My Way to the Back of the Pack...
|