The Ford Barn

1948F-1Pickup · 08-16-2016, 01:05 PM

Is there any tendency for this carb to siphon?
(i.e.: float bowl fuel tendency to transfer down
the carb bores)

By no means is this flathead hard to start when
hot but it's a little more reluctant when hot than
the single half-second button it takes when cold.

I'm thinking if the siphon tendency is there, maybe
I should bring the float bowl level down a hair....

Bruce Lancaster · 08-16-2016, 01:30 PM

Look at the cross sections in the bulletins:
http://www.norgv8club.org/all-dcoume...vice-bulletins and click on Ford_9510_Carbs.pdf
A potential syphon route is up the discharge nozzle...it has two pathways, the main circuit up to the top and the idle circuit up and over. Both have very small air bleeds on the forward leg...I would think that if these were plugged with dirt a syphon could well happen. Float level should be well below discharge routes without some sort of help. Only other real leakdown route would be bad gasket or failed diaphragm at power valve.

Carb bulletin is earlier than your carb but everything is functionally the same.

Ross F-1 · 08-16-2016, 02:03 PM

Modern gas percolates a lot easier than "old" gas. A lot of people run their float setting about 3/16" lower to reduce it going down the throttle when heat soaking.

1948F-1Pickup · 08-16-2016, 04:54 PM

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Yeah, this one I rebuilt a couple of months back. It shouldn't
be leaking or doing anything strange. I did upgrade the base
to a CNC piece from Vintage Speed that looks like it was
formed on the space shuttle, but I needed to do something
with the leaking throttle shaft bores and wasn't enthused
about rebushing.....

I'm going to move the float bowl level down slightly and see
if there's a change (other than being ever so more lean).

08-16-2016, 01:05 PM	#1
1948F-1Pickup Senior Member Join Date: Oct 2015 Location: Socal Posts: 795	Question on original 8RT holley 94 on '48 F-1 Is there any tendency for this carb to siphon? (i.e.: float bowl fuel tendency to transfer down the carb bores) By no means is this flathead hard to start when hot but it's a little more reluctant when hot than the single half-second button it takes when cold. I'm thinking if the siphon tendency is there, maybe I should bring the float bowl level down a hair....

08-16-2016, 01:30 PM	#2
Bruce Lancaster Member Emeritus Join Date: May 2010 Location: Madison, NJ Posts: 5,230	Re: Question on original 8RT holley 94 on '48 F-1 Look at the cross sections in the bulletins: http://www.norgv8club.org/all-dcoume...vice-bulletins and click on Ford_9510_Carbs.pdf A potential syphon route is up the discharge nozzle...it has two pathways, the main circuit up to the top and the idle circuit up and over. Both have very small air bleeds on the forward leg...I would think that if these were plugged with dirt a syphon could well happen. Float level should be well below discharge routes without some sort of help. Only other real leakdown route would be bad gasket or failed diaphragm at power valve. Carb bulletin is earlier than your carb but everything is functionally the same.

08-16-2016, 02:03 PM	#3
Ross F-1 Senior Member Join Date: Nov 2010 Location: NM Posts: 2,438	Re: Question on original 8RT holley 94 on '48 F-1 Modern gas percolates a lot easier than "old" gas. A lot of people run their float setting about 3/16" lower to reduce it going down the throttle when heat soaking. __________________ '52 F-1, EAB flathead

08-16-2016, 04:54 PM	#4
1948F-1Pickup Senior Member Join Date: Oct 2015 Location: Socal Posts: 795	Re: Question on original 8RT holley 94 on '48 F-1 Sponsored Links (Register now to hide all advertisements) Yeah, this one I rebuilt a couple of months back. It shouldn't be leaking or doing anything strange. I did upgrade the base to a CNC piece from Vintage Speed that looks like it was formed on the space shuttle, but I needed to do something with the leaking throttle shaft bores and wasn't enthused about rebushing..... I'm going to move the float bowl level down slightly and see if there's a change (other than being ever so more lean).