Holley 1940 1V carburetor

Destiny has suffered from lousy gas/mileage. Actually it is not the cost of gasoline (1.60 EUR per liter currently) that bothers me rather than the thought that there is something wrong with the engine if too much gas is spent. I already had replaced the distributor, spark plugs and wires, fixed the ignition lock pigtail. The fuel lines and rubber hoses were checked for leaks. The Holley/Autolite 1940 D0PF-K 1V-carburetor has been cleaned and tuned for many times. Actually, there are not so many things to tune in it. It only has idle screw, and choke adjustment. I figured that there must be vacuum leaks somewhere. The leaks would cause that there is not enough vacuum needed to keep power valve closed. In this Holley the ported vacuum operates so that if the vacuum drops (like it does in heavy acceleration) the power valve opens and gives more fuel for the venturi. When the vacuum is available, it keeps power valve closed and the fuel flows through the main jet only. I think my power valve never closed. As I had checked the operation of the power valve itself, the reason had to be vacuum leak in throttle body or elsewhere.

Finally, I made my mind to replace the old carb with a re-manufactured one. I contacted http://www.carbsonly.com/ which soon replied and told that they have "an excellent quality re-manufactured 1 barrel Holley carburetor for the 1965 ford mustang". So I took the chance and ordered it. Six days later the carb arrived to Helsinki customs office where I collected it. Excellent quality was promised and to my ( I must admit, I was a little suspicious ) surprise quality was delivered.

The ported vacuum for distributor comes from the hole in the center.
This Holley is Motorcraft branded.

Spark Control Valve (SCV) on the left.

Choke pull-off vacuum diaphragm on the right

Nice looking one-barrel carb.

The Carbsonly reported that #63 Main Jet was in there so I didn't have to open the body to check it. (The old one has #61, so there wouldn't be a big difference). So there was nothing left for me other than bolt this beauty on the "log" intake manifold along with the new gasket. The engine fired up nicely as soon as I turned the ignition key. 

The air filter bracket is higher than the "original".

I had measured and compared all the diameters and casting numbers between the "new" and the "original" carb. One mismatch was found when I placed the air filter on the carb. The connecting bracket was about 1 cm higher that the one on the "original". I did not want to exchange them as they are secured with pins tapped in the body. So I "lifted" the air filter by adding another O-ring in the bottom.

One O-ring

Two O-rings

The other O-ring is a little wider in diameter to make it sit snug between the first ring and the upper edge of the barrel. This modification was enough to lift the cleaner to fit. Obviously the "new" carb is from some other car model with different type of air filter case. I think Carbsonly might have been able to exchange it if I had known this. Now this is just a hint for someone who plans on ordering one of these re-manufactured carbs.

One small but meaningful fix needed to be taken care for. The fittings of the ported vacuum. In the below picture they can be seen. I couldn't figure how on earth the lower of the two fittings would be able to seal the tube that goes down to distributor's vacuum advance diaphragm. I had never paid attention to this earlier,but obviously this might have had effect to the vacuum leaks also. The local store did not have appropriate new fittings for the old tube, so what they did was a new tube with new end fittings. Actually they used copper brake line tubes, which is thinner than the original steel tube. As there is not air flow through the tube I thought that it doesn't matter.

Vacuum port fittings

The new carburetor and new vacuum line really made a change in the engine. It idles with a very low RPM now. I do not have a tachometer, but to my ear it makes about 500 revolutions per minute. Sitting in the car you can hardly hear that it is running. The car performs  better on the road than earlier. I only have driven about 200 miles since the replacement, but it seems like we are back to 12-13 liters per 100 kilometers. I still have to give her more miles to see the actual effect on the fuel economy. If we'll stay closer to 10 liters than 20 liters per 100 km, I'll be happy with it.