Re: Spica fuel pump/archive search

["R Hirsch" <rhirsch@xxxxxxxxxxxx>]

Biba wrote:

>In #502 Dean Cains makes a rather cryptic remark: "You might also have
>to play with the orifice in the fuel outlet on the Spica pump, and I
>found that a 1mm orifice works well on mine."
>
>*******
>
>Dean, you're making reference to the return line on / from the Spica
>injection pump? What is one trying to accomplish - slow down the fuel
>return to the (Master E2000) fuel pump? If so, why?

On the Spica FI pump outlet port there is (or should be) a restrictor
at the back end of the hose bibb. That is, if you compare the inlet and
outlet Spica pump hose bibbs, the outlet bibb has a smaller opening at
the back end of the bibb.

This restriction is to provide back pressure so the Spica pump sees the
correct fuel pressure (ca. 12 to 20 PSI). Too large a hole in the restrictor
and fuel pressure is too low for the pump. Too small a hole and the fuel
press.
is too high.

The correct way to set the restrictor size is with a fuel press. gauge
"tee'd" into the fuel delivery hose and then try different restrictor sizes
until the fuel press. at idle is 12 - 20 PSI. One way to do this is to
solder shut
the back end of the outlet hose bibb and then use a tiny drill bit to drill
an outlet hole. Enlarge the hole as needed with a needle file to achieve the
correct fuel pressure.

See the Rex Brown article "Plunging into Spica Pumps - About Fuel Pressure"
at:

   http://www.geocities.com/MotorCity/Downs/3837/fuelpress.html

Rich Hirsch
St Louis MO
'87 Milano
'78 Spider
'67 Duetto
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