I'd also like to see a couple more Lbs of fuel pressure, but if the volumes
OK the pressure might not be a real problem. Float level is important, too.
And look for clear fuel lines - I once spent a very frustrating afternoon
discovering that one of my fuel connections had a little flap of rubber hose
that partially blocked the line only after it was tightened.
While the oil in the damper does help control part throttle stuff, it's most
important function in a race application is to provide an accelerator pump
equivalent function as you get back on the throttle. The throttle plate
goes wide open so the volume of air going thru the carb goes up, the damper
slows the rise of the slide so the velocity of the air thru the carb goes
up, causing vacuum at the jet to go higher, and more fuel gets sucked out
than would normally be the case.
This idea of signal strength at the jet orifice is also why the 948 A-series
and the early 1275 Cooper S used the same needles in their carbs for a
period of time. The extra capacity of the 1275 caused the same needle in
the carb to run rich enough to fuel the bigger motor.
The other thing that comes to mind is that you only need a very small amount
of oil - maybe a teaspoonful - in the center tube of the dashpot to cause
the thing to work. The test I use is to unscrew the dashpot from the cover
and just lift it a bit. If there's some damping type resistance, then
there's enough oil. remember that since the slide rises, the dashpot
effectively goes lower in the tube than when it's at rest, and more oil
doesn't make it work any better than just enough.
Anyway, that's my take on SU's. Even after I spent a ton of time studying
the things I couldn't make them work as well as a Weber, so the SU's went
back on the shelf..
Cheers, Brian
At 11:40 PM 7/6/99 -0400, you wrote:
>my take on the oil in the S.U. is that it acts like a shock absorber to
>control part throttle flutter. my full race carbs do not have oil in them
>at all. correct me if I am wrong but S.U.s function well with 4 psi fuel
>pressure, best to run higher pressure (7psi) from the pump up to a regulator
>w/guage located under the bonnet set a 4 psi............this assures adequate
>fuel to the float bowl in all "on track" situations
>I send this to all the list so my I may get corrected if not completely
>acurate
>.........................chuc
>
Brian Evans
Director, Global Sales
UUNET, An MCI WorldCom Company
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