quote:Originally posted by Daniel_Jones:
> Theoretically if a person restrains their right foot, the fuel mileage
> shouldn't be too bad.
Fuel economy can be better than a 4 barrel if properly calibrated. Vizard
reported 18 to 20 MPG on his SBC-powered shop truck with 48mm Webers.
> The 48's were really developed for Shelby's 289 Cobras. They start to show
> restriction issues at around 5,500 rpm's on a 289.
Vizard's testing on a 350 SBC found that 48mm Webers on a down draft IR
intake showed the Webers to be superior in peak power up to around 480 HP,
after which a larger 4 barrel carb on a plenum intake would make more peak
power but not necessarily better average. The independent runner manifolding
provides better power in low and mid-range so the cross-over point for
average power is higher.
Dan Jones
Can't argue with either. Best mileage I've seen with the Webers on my car is 15. Best with a 4179 Holley was 13-14. Of course it is very difficult not to put your foot into either.
I would say that the Webers on an IR (people have put them on single plenum manifolds) have a significantly better throttle response the a single Holley, at any rpm or speed. At least that is what I have experienced.
Over 100 mph, nothing pulls like Webers except a supercharger and possibly nitrous.
When you are driving the car, rather then having the engine on a dyno, I think the power with the Webers is much better over 100 mph then the Holley.
HOWEVER, I am usually trying hard just to hold on, trying not to blink as my eyes are watering from bouncing around, rather then sit there thinking, are the Holley and the Webers about the same?
Do you have a print out of that dyno run with the SB Chevy, Webers vs. Big Holley? I'd like to see that.
I have a feeling though that a nice set of two Holleys will yield the response of the Webers with the top end of the big Holley, and better overall drive-ability then either.
That certainly appears to be the case on my 347.
Don't forget that initially you are driving on just a 2v until about 3200rpms, and the secondaries are vacuum.
Lack of a manifold for the C of course is the killer to my theory for now though...just for now.
