I rebuilt my carb a while back (1954 Merc - stock) and my mileage is only about 10 mpg.  I often smell raw gas, especially on down grades, and my exhaust tips are getting carboned.  I pulled the plugs and they are good and running clean.  I read some time ago that the power valve actuator cover seal could break due to backfiring and that the result could be poor mileage but that it would run okay.  I had a lot of backfiring when I inadvertently installed a distributor with the wrong amount of teeth!  (Took a while to figure that one out).  Does anyone have direct knowledge of this phenomenon?  Also, is there something else I should look for?  The engine runs well, have to pump it quite a lot after having sat for many days and is slow to start on very hot days when the engine is warmed up.

I can tell You that its hard to start after sitting because the Gas in Float Bowl evaporates. The vents are open to air. If its annoying just ad an Electric Pump to fill Bowl before starting. I can't help with the other. I just gave up and added a later Holley and Distributor. Never  going back to stock.

  

I’m assuming you have the original model 2140 Holley 4V on your engine but most of the following also applies to the ’55 and up model 4000 Holley 4V carbs.  Check to see if the secondary jets protruding into the external venturi tubes (model 2140 carbs) have a 45° bevel on their ends.  This bevel was an added running change during the ’54 model year.  If the ends are flat and parallel with the externally mounted venturi tubes, then you’ll need a 1/16” slot at the bottom of the tubes or a bevel at the tube ends to create a vacuum break for the fuel.  The flat ended jet tubes were notorious for flooding issues when the engine was shut off but the potential is there for fuel to also siphon over into the secondary tubes during running conditions.  If it’s the later model 4000 Holley carb, then insure that the anti-siphon holes in the top fuel cover plate are open.  It only takes one of these holes to be stopped up to cause the fuel to siphon over to a secondary throttle bore and empty the fuel bowl.
 
There are several areas to look at regarding the power valve; the Ford parts manual calls this a jet.

1. The rubber seal on the actuator (aka economizer) may be leaking which makes the power valve activated all the time rather than being shut when sufficient manifold vacuum is present.  I like to use some white grease on both sides of the rubber seal during its installation and then test it before installing the top cover to insure it holds a vacuum when the economizer spring is depressed.  By design, the power valve is open when the engine is not running or is being started up.  Once started, the manifold vacuum is sufficient enough to permit the power valve to close by allowing the economizer to be pulled up.
2. Check the gasket under the power valve; it does need to be seated tightly and squarely.
3. The air cleaner stud hole in the carbs' top cover must be sealed.  The brass tube within the air cleaner stud hole can leak at its perimeter which keeps the economizer from working.
4. And last but not least, the ‘brass’ power valve itself must be in good condition with its internal spring keeping the valve seated securely when the economizer is in the ‘pulled up’ position.

 

Lorena, Texas (South of Waco)

If you want the name of a good rebuilder for these carbs there is a guy in PA who is an expert in them.


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Thanks a lot for the help.  I will tear into the carb in the next week or so to check the e z and more obvious potential issues and will get back with you if I have specific questions.  Paul2748, please give me the name of the re-builder.

On a related subject, I have a another, later model teapot that has stamping ECZ-9510-L and LIST 1-162 2.  Can anyone ID this?

I think your other carb is from a 56 Ford.


~DJ~ AKA "Bleach"
1956 Ford Fairlane Town Sedan 30K original miles

He did two for me and they run very good.  The rebuilder is Mike Suter in PA  215-757-3678

The ECZ-L carb is likely a 56 sedan.  The Holley list I have shows all 1162 lists as for a 56 292..  Tbirds used a different prefix number





54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

The List #1162 carbs came on the 1956 Ford and Mercury equipped with the 292 engine.  List #1161 carbs were on the 312 equipped 1956 Fords & Mercurys.  List # 1163 carbs were supplied on 292 equipped 1956 Thunderbirds while List #1164 carbs were on the 312 equipped 1956 Thunderbirds.   List #1268 carbs were on the factory supplied dual quad (2X4) intakes for all 1956 model engines.

Lorena, Texas (South of Waco)

About the backfiring, Are you saying you meshed a 55 and up dist with a 54 cam. I never thought that combo would even go in.

I have found out that the suffixs on the carbs were due to a change in the discharge nozzel assemblys sizes.
I dont know if any other changes were made and I dont know if the later suffix carbs went smaller or larger on the nozzels.

I have to get a few apart and measure them to find out.

Thanks to Tim at Daytonn Carburator for that tidbit of great information (and more).

Oldmics