[alfa] Sight Glass Question [was Re: Biba's cutting out...again]

[C2slayman@xxxxxxx]

Hey Biba,
    I was thinking the sight glass you were talking about was the float bowl 
on the carb - remember those old American carbs circa the '40s & '50s?  But 
now I remember you have Webers - no sight glass in the float bowl - right?   So 
is the sight glass you are talking about is the inline filter?
    The sight glass getting full overnight might be explained by cooling off. 
 The air you see in the sight glass will contract when it cools down 
(pV=nRT).  Any residual gasoline pressure in the line will just compress the air as 
the engine compartment cools overnight.
    But I think the fact that you are seeing air in the sight glass while the 
engine is running is interesting.  I don't have any experience with those 
types of filters.  I would have thought it should be nearly full all the time if 
the pump is supply enough gasoline to the carbs.  Any signs of air bubbles 
would indicate that the float valve on the carbs (Webers use float valves to 
control fuel level - right?) are accepting more gasoline than the fuel pump is 
delivering.  So air bubbles are getting from the float chamber back into the 
filter.  This doesn't sound right to me.  I would have thought that with a 
properly running fuel pump, the lines and filter would be charged and all air would 
be purged from the system.
    Are any other Alfisti running an inline filter with sight glass?  How 
does it behave?

Cheers,
Charlie

PS  As you can see, my experience with fuel systems is restricted to 
Rochesters, Spicas and Bosch.  I don't know the details or guts of the Webers.  (But I 
did have a downdraft 2bbl Weber on my Pinto, for what it's worth!  Actual 
factory stock!  ;-> )

In a message dated 10/23/03 5:28:36 PM Pacific Daylight Time, 
owner-alfa-digest@domain.elided writes:
Date: Thu, 23 Oct 2003 16:00:30 -0700
From: alfacybersite <acs@domain.elided>
Subject: [alfa] Biba's cutting out...again

.................................


Today, 'only' 93 degrees. Started out with sight glass full. Drove eight
miles, sight glass still full. Drove fifteen miles, sight glass was
7/8th full. Drove five miles, sight glass was 1/3rd full. Aha! I said to
myself. Since I was now heading home, revved as much as possible
figuring I could, at worst, walk home. Got her up to 90 on a short
stretch. Ran like a top. Got 'home'. Sight glass (between carbs) was 1/2
full - (two hours of sitting later, still the same).

Please explain how sight glass gets full all by itself overnight and
varies considerably within literally minutes? To repeat, I've checked
voltage to pump when hot and ground checked out perfectly.

............


Dunno,

Biba
Irwindale, CA USA
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