But, but but but but (just like my 3- year old nephew says it)
Fuel flow at anything but extended WOT at high rpms is almost static. The pump
has enough excess capacity to keep constant pressure in the entire line,
overwhelming any real drag losses in the tubing.
You're sending a fixed amount of fuel through a fixed aperture
(the needle valves)
So while the larger volume of fuel in the line will take longer to fill
if the line runs dry, once it's full, flow THROUGH THE NEEDLE SEATS
will be the same. And as fuel's incompressable, it really won't affect dynamic
flow in the entire system very much either. In fact, in theory it should
increase it a hair, as there's less resistance to flow in a larger line.
So yes, if you pop the 5/8" (is it REALLY that big?) hose loose, it won't look
like a gusher- but if you pop the float lid off, fuel will squirt out of the
needle valve like it's supposed to.
I'd look at that filter... or that pump...
fwiw,
Toby
> Absolutely! Basic Fluid dynamics, if you open the aperture wider (smaller to
> larger fuel hose), pressure drops. The relationship is inverse to
>pi-r-squared
> (area or opening), in square inches (or square mm, whichever you measure). I
> think the pressure at the carbs (on my SU's) has to be about 4psi. (3-6psi
> range, off the top of my head, but according to the manual) I recently put a
> manual pressure regulator on them to ensure I wasnt over-pressuring the
>float
> bowls a higher RPM's.
>
>
>
> BTW, you'll also get a minor (but probably imperceptible) drop across the
>fuel
> filter.
>
>
>
> Perry Smith
>
> '68 2000
>
>
> "Brucciani, Chris" <CBrucciani@archinsurance.com> wrote:
> Thanks to fellow listers Pinky's electrical gremlin has been calmed (for now).
> I have a hunch that I may be lacking fuel pressure at the carbs. I have an
> electric fuel pump located on the frame. It feeds into an inline gas filter -
> out to about a 5/8" fuel line - into another inline filter (I need to remove
> this but before I changed the hard fuel lines and coated the gas tank I had a
> lot of rust) then into a =" or so fuel line to the carbs. It doesn't appear
> that I get good flow to the second filter. Would a too large fuel hose
> contribute to a lack of fuel pressure?
>
> Chris Brucciani
|