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At long last I have taken delivery of my 745 phaeton and enjoying getting to know it.

My first small issue is a rather bad fuel leak when I fire up the engine. The vacuum pump has been bypassed at some time and an electric fuel pump has been installed.

I dont think its the pump itself that is forcing the leak as I have run the pump on its own and it seems not to leak. Once the engine is running the fuel literally pours out of the bottom of the carb from both points I have circled in the photo.

Do any of you good folk have any words of wisdom before I start to take out and dismantle the carb?

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The left circled item is where the fuel enters the fuel bowl. There is supposed to be a copper crush gasket between the bowl and the fitting. A red fiber washer will also work. Under the retaining nut (which should be an acorn style nut) there should also be a red fiber washer.

Same thing for the dash pot adjuster doo-hickey (sp?): a red fiber washer between the bowl/throat and the valve. If the washer is present, it is possible the small rubber bushing in the valve assembly is shot. You can get a re-build kit for these carbs from the Carburetor Shop or others.

Note: do not over tighten when putting the dash pot adjuster doo-hickey back on. Maybe 3-5 lbs of torque, or you risk cracking the bowl/throat piece.

Tom

Another aspect to consider. The updraft carburetor needle and seat is designed to only handle fuel pressure under a gravity head of less than a foot, and an electric fuel pump feeding directly to the carburetor will OVERWHELM it and profusely leak. There are folks with Detroit Lubricators that use an electric pump to feed the vacuum tank when the car has been idle for a time, or when a little more is needed when vacuum is low (like climbing a long hill) but feeding the carb directly is not likely to ever be satisfactory.

Thanks guys.

In the fullness of time I intend to reinstate the original vacuum pump. It is still all there, even the glass bowl but it has been disconnected from at the top and at the bowl.

I dont know why it was abandoned in favour of an electric pump.

I dont know how the vaccum system works so I guess I have two jobs to do.

I know the car has been used successfully for the last 5 years or so with the electric pump and it certainly seemed ok when I first looked at it, so I would like to get it working properly again.

Thereafter can anyone give me any details on how the vaccum system works so I can remove this and have a look to see what, if anything, is wrong. Once this is good to go, I will reinstate it and ditch the electric one.

Thanks again for your feedback and advice

Vacuum tanks (usually Stewart-Warner) are well described in most of the car service books and publications of the era like Chiltons, and no doubt are available on the web as well, though I don't have a link. There are also professional rebuilding services. But it a nutshell, manifold vacuum is routed to the canister and that vacuum draws fuel from the tank into a reservoir also within the unit and from there the fuel runs by gravity to the carburetor. There is a float system included as well which I believe (?) controls the vacuum. Generally, failure of the vacuum tank is from a vacuum leak (gasket, often, or warped casting) which prevents it from filling with gas.

No doubt one of our gurus with direct hands-on experience will come along shortly with better info.

Vacuum tanks are often abandoned by the uninitiated because either they're too lazy to repair it, or think of it as a reliability issue (which it isn't, when properly rebuilt).

Don't know which model system Packard used but there are a couple of nice pdf descriptions of how a Stewart vacuum tank operates on a Hudson site which may be similar enough to help.hudsonterraplane.com/tech/stewart/StewartVacuumTankModel113-UBooket2039.pdfhudsonterraplane.com/tech/1927/StewartWarnerVacuumTank2-11-27.pdf

Here are some photos I took of mine during cleaning. They are very simple devices.

packardpaddock.com/page2/page4/page4.html

Some related discussion here:

forums.aaca.org/f125/using-electric-fuel-pump-vacuum-tank-299045.html

Dear KTS68:

I like the vacuum tank system and strongly advise against putting any electric boosters in the system because they pose a huge fire risk.

The only time I would bypass the vacuum tank with a pump is when the motor has insufficent vacuum due to mechanical wear or when someone has destroyed the original equipment. In such cases it is best to have the carburetor overhauled and refitted with a needle designed for pressure.

Most likely your V-tank was bypassed because one of the seats for the valves in the tank broke loose from the pot metal and disabled the unit.

There is an outfit in Arizona "Classic Carburetors" that has been recommended to me as a good place for such work. Maybe they can help you out.

One feature of the vacuum tank is the fill plug that precludes the need for a pump to prime the motor after long storage. The plug is on the top of the tank and you fill the tank prior to starting. The plug only gets tightened slightly more than finger tight(snug). The Packard manual claimed this was not necessary. They claimed the motor need only be cranked for 10 seconds to fill the tank. I never tried this because it strains an 81 year old starter motor.

Also, on the timing cover of the 7th series Custom 8 is a vacuum assist pump. This unit is probably in need of serivce as well. It can be tested with a vacuum gauge.

Good Luck.

Thanks everyone for your sage advice.

I took the carb out and replaced the fibre washers in the mixture control valve and the chamber supply strainer / elbow.

Of course this required the use of metric washers and a whole load of filing and cutting to get them to fit, with gasket sealer to make sure it all went together properly.

After reassembly I pulled the choke and cranked the engine and fuel sprayed everywhere out of all parts of the carb! A quick call to the previous owner reveald that the choke is very much a "steroid injection" and it floods immediately. He said it was hardly ever needed and even then only for less than 1 second (ie push it back in while still cranking......)

15 minutes of drying-out time later and I tried it again "sans choke" and hey presto, fired up straight away and no more fuel leaks!

So first job done and 100% success rate. This Packard ownership thing is a doddle!!!! (famous last words!?)

The previous owner revealed that it actually has two electric pumps fitted with a three-way switch - belt and braces apparently. He also said that there is nothing wrong with the vaccum pump but he found it unreliable at times.

I hear what you guys say about the fire risk, and I agree so as soon as I have checked the vaccum pump over, I intend to revert back to it. I'll keep the electric pumps as backup until I'm happy that I can get it to run as nature (Packard) intended.

Thanks for your help