SPICA manometer readings

[Bruce Giller <bgiller@xxxxxxxxx>]

	I hooked up my MC manometer (called Carb Stix) to my '73 GTV.  I used
some vacuum 'T' fittings as adapters - on leg was 1/4" for connection to
the head.  The other two were 3/16"; one for the Carb Stix tubing and
the other for ambient air.

	Started up the car and let it warm up at idle.  I was expecting to see
identical vacuum readings for within the two pairs; 1&2 cylinders and
3&4 cylinders.  But what I got was that between the cylinders in a pair,
one was about 4 cm Hg higher than the other.  But between the pairs I
got identical readings between 1&3 and 2&4.  If memory serves, 1&3 were
low and 2&4 were high.  I played around with the butterfly adjustment
screw and could bring the 3&4 pair lower than the 1&2 set but between
3&4 the same 4 cm Hg difference remained.  I set the butterflies when I
matched up 1&3 and 3&4. 

 	With everything assembled, I can kill the engine by placing my finger
over the idle orifice - thusly I'm assuming that the butterflies are
completely closed.

	Has anyone else seen these sort of vacuum numbers when using a manometer?

	Sidenote:
	On MCs, you try and get all the carbs to read the same (+- 2 cm) since
each carb is adjustable (some bikes have one non-adjustable carb and you
match the other carbs to that carb).  Can be somewhat a tedious process
since my bikes are air cooled and you need to let them cool down when
running at idle in the driveway.


"Is dis a system???"  Mr. Natural

Bruce Giller
Takoma 'Radiation-Free-Zone and Finally ReUnited' Park, Md
'73 Alfa GTV 2000
'86 Alfa Spider
'72 Moto Guzzi Eldorado

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