CARBURETOR INFORMATION
RENNER'S CORNER
AIR CLEANER USE CAN RUIN YOUR ENGINE !!!
NOT AN OPINION BUT A FACT !!!
ALL carburetors released by ForD
for use on THE Model A AND B ENGINES
had the float bowls EXTERNALLY vented.
BELOW IS A DOCUMENT RELEASED BY ZENITH
WARNING OF THE NEGATIVE AFFECTS OF USING AN AIR CLEANER
ON EARLY FORD VEHICLES WITH EXTERNALLY VENTED FLOAT BOWLS.
the use of an air cleaner of any type will negatively
affect the air to fuel ratios AS THE FILTER GET DIRTY.
Even with the proper jetting the carBURETOR
will END UP beING very rich !
The excessive fuel going in the engine
will END UP doING MUCH more damage than the dust
in the air BY WASHING THE OIL FROM THE CYLINDER WALLS.
These carbURETORS were not designed for air cleaner use!!!
To allow the use of an air cleaner
the bowl vent must be PLUGGED AND relocated
to the INSIDE of the carburetor near the choke plate area SO
THAT THE ENGINE CAN ONLY GET ITS AIR FROM ONE SOURCE.
This is called A pressure balancing CIRCUIT.
It would take a lifetime to wear out an engine
with the dust that's on our roads today.
GAV SETTINGS:
The dash controlled GAV (gas adjusting valve ) is a carburetor high speed circuit adjustment.
It is used to tune / optimize the air to fuel ratio of the carburetor at engine speeds above 600 rpm.
Set it to where it runs best for the current operating conditions.
Such as engine temperature, outside temperature, elevation, fuel type, jetting etc...
There is NO rule / set position for this.
Every engine set up and condition is different.
One turn open is max flow, so no point in turning more than that.
Typically anything over 1/2 turn should raise red flags
that you have a vacuum leak somewhere requiring extra fuel to be in ratio.
Not to be constantly turning it but get to know where your engine performs the best
by adjusting it occasionally it is NOT a set it and forget it !
The dash controlled GAV (gas adjusting valve ) is a carburetor high speed circuit adjustment.
It is used to tune / optimize the air to fuel ratio of the carburetor at engine speeds above 600 rpm.
Set it to where it runs best for the current operating conditions.
Such as engine temperature, outside temperature, elevation, fuel type, jetting etc...
There is NO rule / set position for this.
Every engine set up and condition is different.
One turn open is max flow, so no point in turning more than that.
Typically anything over 1/2 turn should raise red flags
that you have a vacuum leak somewhere requiring extra fuel to be in ratio.
Not to be constantly turning it but get to know where your engine performs the best
by adjusting it occasionally it is NOT a set it and forget it !
MODEL A INTAKE MANIFOLD PORT MATCHING
Necessary when installing a Model B Zenith carburetor on your Model A.
The Model A intake is 1.18" diameter and the B is 1.30" diameter.
The step in diameters will have a negative effect on air/fuel flow.
Make the transition smooth by port matching the intake to the B diameter.
It is not necessary to bore or chamfer all the way to the Y to get most of the gain in power.
If you think that's necessary then buy a Model B manifold and get on with it !
Necessary when installing a Model B Zenith carburetor on your Model A.
The Model A intake is 1.18" diameter and the B is 1.30" diameter.
The step in diameters will have a negative effect on air/fuel flow.
Make the transition smooth by port matching the intake to the B diameter.
It is not necessary to bore or chamfer all the way to the Y to get most of the gain in power.
If you think that's necessary then buy a Model B manifold and get on with it !