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Vacuum fuel tank question


vergil
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Thanks to the encouragement of some of you out there I finally have the vacuum tank on my '16 all hooked up and functioning.

With the old electric fuel pump I was able to climb hills at a steady 30-35. How should I tackle long, gradual or steep hills with the vacuum tank without losing pressure?

Also, I was advised that it isn't necessary to warm up the engine, but I'm finding that it does help in getting it past a rough idle.

Many thanks!

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Vergil,

Welcome. I have not tried this but years ago I had an English Ford that had vaccuum wipers which I found out continued to operate long after the engine was turned off. The secret was a quart can sized tank up under the fender tied into the system. One could fasten a similar tank up under the dash and tap into the vaccuum line. That should allow continuing up most hills without problem. Let us know if it works for you.

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Engine warm up is very important, especially in older cars. The internal parts of your old motor are designed to fit well, when they are warm and expanded.

The idea of not needing to warm up is based on marketing and modern engines. They do have short warm up times, but try marketing that to a soccer mom.

An engine will run more efficiently at full operating temperature. Further, moisture in the crankcase will not burn off until the engine is hot and running for a while. If the engine is not warmed up and/or runs for short periods, the oil will oxidize and more sludge will form in the crankcase.

At about 70F, my '25 takes about 10 minutes at fast idle to warm up...that's without a thermostat. I'm installing a thermostat now to improve things.

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I have never had that problem on a car with a vac. tank. You will still be pulling a vac on the tank even when going up a steep hill. On cars like a Model T where the feed was gravity you had to make sure your tank was full or back up a hill. Not what you want to do in a model T with its quick steering. If you want to try Rogers solution look for a VW which had a series of plastic balls located under the hood that stored a vac.

Jan

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Thank all of you for some really great suggestions. Not sure I want to go with Rodger's solution just yet.

Mich, yesterday I installed an auxiliary electric pump snd would like to connect it to the main line with shut off valves but can't find valves. As it is, I have to disconnect the vacuum line and then connect the electric pump.My idea is to be able to reach underneath and just turn a valve should it ever become necessary.

I'm fairly certain the problem I had recently was due to the length of the grade and the 30-35 speed.

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I have used vacuum tanks on my cars for 50 years and have never had that problem. If the tank is working properly it will only draw vacuum to fill the inner tank, the needle valve then closes the vacuum and won't open again until the gas drains down by gravity. When the vacuum opens you will lose some power but only for several seconds, this is usually only noticable at idle. When you use an electric fuel pump you are putting more pressure on the needle and seat. The old carburators were not designed for this and could flood.

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Over the years I have noticed large capacity vac tanks at swap meets, they apparently were fitted to trucks of this era perhaps you might find one of these.

The other thing I have observed is the number of engine fires where electric pumps have been fitted. Typically a backfire has initiated the fire, and the electric pump which continues to work just fuels the fire.

As to going uphill or pushing into a headwind with the throttle wide open, you will lose vacuum and eventually lower the vac tank level to the point where the carb will starve for fuel. My 25 Maxwell vacuum is drawn by the engine oil pump so it doesnt suffer these problems, makes me wonder why other manufacturers didnt follow this practice, plus if the oil pressure failed then the engine would run out of fuel and stop thus preventing further damage; lateral thinking perhaps ?

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When my Mom was alive I had to climb a very long steep hill to where she lived. I would always stop at the same place Just before the top of the hill. Took me a long time to work out that the vacuum tank had run out of fuel That's why I installed an electric pump I put it in so it would pump into the vacuum tank to top it up works fine as long you don't leave it turned on to long. Mick

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I have a 20 DB touring that came with an electric pump on it and a funky vacuum tank/carb float modified mess. I removed that stuff, replaced with good vacuum tank and left the electric pump inline. It draws thru the electric pump just fine so I do not have to run it unless the car runs out of gas or something, then I can turn the pump on and fill the vacuum tank, but I DO NOT leave it running. I was surprised that it drew thru the electric with no problem.

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If you have a diaphram pump it will draw thru the pump but not if it is rotary. If you want to put a pump in then you also need to install a push button switch that is normall open and you close the circuit and hold it when you want to run the pump. I used to do this on engines that required a priming circuit. With all that said I do not believe in installing accessory electric fuel pumps as they can overwhelm the rest of the system and cause leakages.

Jan

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<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: hchris</div><div class="ubbcode-body"> My 25 Maxwell vacuum is drawn by the engine oil pump so it doesnt suffer these problems, makes me wonder why other manufacturers didnt follow this practice, plus if the oil pressure failed then the engine would run out of fuel and stop thus preventing further damage; lateral thinking perhaps ?

</div></div>

My 29 Dodge Bros P-U has the vacuum/oil pump that works the same as the Maxwell, if you lose oil pressure the fuel shuts off, saving your engine. I thought all the Dodge Bros vehicles had that. It also keeps vacuum to the tank even on long grades so the tank doesn't empty due to lack of vacuum.

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