Holley 1940 Questions & Answers

Holley 1940 Accelerator Pump Circuit Problem

Rebuilt the carb, ran great for a few minutes then the RPM’S dropped and now all I can get is a dribble of gas when hitting the throttle. Not sure what’s going on. Any suggestions. Ill pull the carb off and pull it back apart. When it’s cold and you hit the throttle all I get is a dribble running down the inside, no squirt of fuel.


Most likely the problem is in the accelerator pump circuit. Did you run thin wire through all of the passages, especially at the main discharge? Ethanol leaves deposits behind that cleaners can’t remove. If you pump the throttle linkage and don’t see gas squirting into the venturi, then you have a blockage somewhere.

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Holley 1940 CarburetorHolley 1940 Carburetor


I believe I have it fixed. I was watching the accelerator pump rod while moving the throttle by hand and the pump rod was not moving. The 1940 has that triangle piece mounted to the front of the carb with the 3 slots in it. When  i actuated the pump rod by hand the car ran perfect. So i took the carb back off to see if the pump piston was hanging up. Everything looked good, other then the movement of the pump being really “stiff”. I cleaned and checked the accelerator rod for nicks or burrs and it was fine. The piston is a lot bigger in diameter then the one I pulled out. I guessing mine had shrunk over time. I put the carb back together, sprayed the outer linkage with silicon spray and just kept working the pump by hand until it got easier. Put it back on the car and its been running good, very smooth idle, no leaks. I still have to drive the car and check it all out.



I hope you are doing fine, I just send you an order to your webpage # 10983, because we need to repair the carburetor installed in our Hobart JET EX II generator, the manual of the generator says that the carburetor is a Holley 1940 D7JL-9510 A , however the plate say motorcraft but the part numbers are matching, so I am attaching you a couple of pictures for your info. Just in case I ordered another stuuf that is not going to work, please give me your assessment on this one.


Holley made the 1940 for Motorcraft and many of the 1940 1 barrel carburetors will have a Motorcraft tag even tough they are really a Holley. It is the same carburetor and all that really matters is the carburetor number. In your case the D7JL is what you should match in the list of carburetor numbers for any particular kit.


Recent Posts

Choke Types

We have 4 different types of chokes, Intregal, Divorced, Electric & Electric Conversion.

Intregal Choke

Integral ChokeThe integral choke is mounted on the carburetor, either near the top, or near the bottom. The illustration shows the choke mounted on the top of the carburetor. The thermostat is heated by a heat tube that runs down to the exhaust manifold. The heat tubes heats up the thermostat and moves the choke valve to the open position. A vacuum passage in the carburetor feeds up to the choke housing and helps pull in the heat from the heat tube. Some of these chokes will also have a hot water jacket running through, or on the thermostat to facilitate heating.

Divorced Choke

Divorced ChokeThe divorced choke typs has the thermostat mounted in the intake manifold instead of on the carburetor. In this illustration, the arrow points to the thermostat which is covered by a metal shield. A rod connects the thermostat to the choke lever, which controls the choke valve to be opened, or closed. As the intake manifold heats up, the thermostat mounted, expands, opening the choke valve.


Electric Choke


Electric ChokeThis is a typical electric choke mounted on the carburetor, which is integral. In this case there is one wire on the choke thermostat. This is the 12v source, which all electric chokes use. The thermostat is grounded via the carburetor itself. Some electric chokes will have a 2nd wire (ground wire), which is connected back to the carburetor. When the key is on the thermostat is heated up, opening the choke valve.

Electric Choke Conversion


Electric Choke ConversionThis is a typical electric choke conversion kit. This is used to convert an integral, or a divorced choke to an electric choke. These choke kits come with a temperature sensor that bolts on to the intake manifold, which provides more accurate choke control than with an electric choke without the gauge. The electric choke conversion kit is not used for a manual choke conversion. The choke housing must be in place in order for it to work.
This choke installs in 20 minutes or less with no special
tools. Remove the old choke thermostat and replace with this choke conversion kit.
Attach the temperature sensor under an existing engine bolt.
Wire the positive wire into the vehicles electrical system. Ground the choke to the carburetor.
Complete instructions are provided for each application.


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