Hand fuel pumps - can anyone tell me why?

I see those hand fuel pumps in a lot of the traditional "Rodder's Journal" cars, but I got to thinking about it the other day:

I see all over the place how critical it is that 94s and 97s (and other similar) be run at 2-3 psi. That being the case, how do/did the hand pumps help anything? I would think all it would do is overflow the float bowls. What am I missing?

 

The hand pump replaces a mechanical one.

I suppose if you use a hand pump to replace a mechanical one you will need a gauge to tell you how much you are pressurizing the system. As you said, the old carbs don't like much more than a few pounds of pressure.

I have an Eelco pump that's flanged so it can be dashboard mounted.....with a gauge mounted alongside.

 

The cars that ran hand fuel pumps, model T:s, A:s, sprint cars, had the fuel tank in the cowl and gravity feed to the carbs, which will give hardly any fuel pressure at all.

If you change the model A updraft carburator to a downdraft or put in an v-8 with a high rise manifold you will have almost no pressure height left. Since you can have trouble getting enough fuel to carbs even at 2-3 psi the problem is even bigger on race cars that ran alky.

The hand pump put air pressure in the fuel tank increasing fuel delivery capacity.

/Mikael

 

How often would you have to "pressurize" the tank? Every few seconds, every few stops, or everytime you drive?

 

Makes sense for those engines that had no fuel pump provision, but what about the V8 guys who did? I can't believe a mechanical pump uses enough power to justify erratic fuel pressure and having to pump it every few seconds in a race...

 

If you change the model A updraft carburator to a downdraft or put in an v-8 with a high rise manifold you will have almost no pressure height left. Since you can have trouble getting enough fuel to carbs even at 2-3 psi the problem is even bigger on race cars that ran alky.
/Mikael[/QUOTE]

Not totally true. I have a flathead V8 in a Model A with the original tank. I have an electric pump because there wasn't any room for the stock pump due to the firewall interference.

A couple of years ago I was on the way to a show when the pump quit working. I by-passed the pump with an extra piece of hose I had in the trunk. I didn't notice any difference in performance even though my engine has a Thickstun hi-rise manifold. I did an experement the next day. With a spare can of gas, I drove the car until it quit running on gravity feed. When I looked into the tank it was bone dry. The next experiment was to get on the highway and open it up. Took it up to about 80mph (speedo only goes to 80) and it ran fine.

I still have the electric pump, but it's nice to know if it fails, I'll still get home.

 

The way I heard it is that on a midget sprint car, if you forgot to pump on the straights the car would stutter at the end of the turn. On the other hand they have very small tanks.

 

I'm not sure....I ain't that old

I used it on my dragster for awhile because the Hilborn pump drive was located under the magneto at the top/rear of the engine and the car was hard starting as a result. The Eelco tank was mounted low, between the frame rails, ahead of the engine and I thought it might help to prime the pump.

 

The hand pump doesn't pump fuel........it fills the tank with air. The air displaces the fuel in a sealed tank. The last thing you want on a race car on a fair grounds dirt track is a vented tank spillin fuel on your lap or in your face BUT!! you want the float bowls damn FULL when you punch the button comming outta the corner and REMEMBER the track is a horse track There is shit flyin everywhere You bog at the corners exit YOU WILL GET RUN OVER
So you punch the botton and shoot down the back straight PUMP a couple times and Back that sucker IN! STAND ON IT AGAIN! Look for that pretty girl screamin in the stands and PUMP
If you are in front you have a chance to smile at her before you toss the whole f'n mess into t-one

If you fast and lucky your there out front with time to take a berath. If not the wolves are biting at you and sliging shit all over you

THIS IS A WAR!!!!!!!

Do this 25-50-100 times !!!!!!

Your overalls are full a dirt at the waist your face full a OIL and FUEL and the adrenline makes you feel like your ten feet tall!
Now think about that trophy girl and hope the your lady in the stands don't get madd when you hug and kiss her

Get the idea.....that's what tghe hand pump is for!!!!!!!

 

Nice story Bluto. It's always cool hearing from someone who know how things were back in the day. That's probably why most of my friends are in their 60s and 70s.

 

yeah - great story Bluto - got me all pumped up - i need to go do some donuts right now

 

These things entered rodding straight from Bluto's race cars, but did slightly change function in the early fifties or so--the hottest street rods of this period were dual or triple purpose cars, and ran gas on the street and alcohol at the lakes or drags. The manifold was usually swapped out entire for one with alcohol carbs, and the weekend juice was fed from a WWII aircraft surplus or Moon type tank with the help of the hand pump. Aside from the need for a complete second system, alcohol required volume beyond the capacity of a normal flathead pump, and was not kind to standard diaphragms and such either. The handpump delivered the goods with no problems, especially since drag and lakes runs didn't last long. These pumps were used on many pre-WWI stock autos as well, and elderly Caddy pumps were the source before Moon and Eelco started making them. I think but don't know for sure that they were used as boosters on these OEM applications, keeping the fuel moving from low tanks on steep hills but not used in most driving.

 

So it's a sexual thing, no?

I read once where the Gar' would pump his like crazy so it filled the carbs, submerged the floats and made the nitro overflow... no, make that inject into the motor!

Sam.

 

Funny how time has a way of distorting things, coupled with numerous re-tellings and you have a quite different idea of how things were.

The hand pump DID pressurise the tank, but not on any stock automobiles that I have seen/studied.

They were used extensively on VERY early racers (think the naughty auties and teens) because gravity feed was inconsistent on a bumpy race course with fairly high cornering loads, and the vacuum tanks were never very reliable at all (these were the favoured methods on factory stock cars).
If you are conversant with your early race history, you know that there was always a riding mechanic, until Ray Harroun, in a Marmon at Indy in 1911, ran the winning race without a mechanic on board. (This started the trend toward single driver's, but it didn't happen overnight.)
The mechanic's jobs were numerous: he was the rear view mirror; navigator; mechanic; tyre changer; as well as the fuel pump!!
The driver had his hands full with actually driving the thing, those early race cars being a real bear to drive at all, never mind at speed.

Of sprint car history I know less, but I believe that the hand pumps were used as an auxillary, if at all.

Certainly race organisers would have been aware of the many fires both started and fed by pressurised fuel tanks, fuel gushing out of broken lines fed by pressure in the tank that could not be bled off easily. Which would make me think that pressurised tanks would have been outlawed by either organisers or common sense well before the fifties, bro.

Cosmo

 

Bluto's only a kid in his 50's... but he's been around....don't age him too fast!

 

Well, here's three drag cars that ran at NHRA events in '56 and '57. Pumps all. I believe Moon was selling the pumps into the sixties.


Mutt

 

So can anyone explain why this pump has a spring-loaded, 2-piece handle and how it is designed to be used, please? Trying to work out the fuel system on an old sprint car.

 

If you get a copy of Don Garlits autobiography there is an interesting
fuel pressure pump reference. He explains about his fuel buring
Chrysler motors laying down at the 1,000 ft or so portion of a run.
He talks about pumping air into the fuel tanks to build pressure to
make it to the lights under maximum power. This was in the early
days when he still ran carbs on the race motors. I have an early
hand pump that came with a 392 Chrysler race boat motor featuring
6 stromberg 97s It was still plumbed in to the tank which fed the motor.
It appeared to be the only fuel delivery system for the motor. I could
not be certain. When pressured up it had no problem pushing gas to the motor on an engine stand for short duration runs.

 

When we ran flathead V8s, we used the original fuel pump to push air to the sealed fuel tank to push Methanol to the carbs : that way we could do away with the hand pump & also have a fairly even fuel pressure : higher RPM = more air/ lower RPM = less air, so it was pretty much self regulating , & did away with something else for the driver to worry about during a race.

 

Thanks. That could be the deal with my car - it has a mechanical fuel pump on the side of the motor but there is no fuel pipe going into it. The outlet goes back to the tank. Then there is a rubber pipe coming out of the tank straight to the carbs with the cowl-mounted hand pump Tee-d into it.

 

Some early cars, like Cadillac, pressurized the fuel tank instead of using a fuel pump or vacuum tank. They had an air pump attached to the motor, and a hand pump in case you needed it to start the car. Race cars used the same idea, sometimes with just the hand pump. If your tank is half full it will hold pressure a long time and slowly go down as you use up the fuel.
There were also hand operated oil pumps on some early cars and motorcycles. The oldest race cars had a riding mechanic for a reason.

 

I remember cars with blowers having those hand pumps with the fuel pressure gauge..

 

Great to see a post from Bluto...

I've got a brass hand fuel pump from Cessna I'm going to fit to a spare fuel cap. I will carry it the Modified as a get you home device if the electric Carter pump fails.

 

In the early midget & sprint car world ,guys would run the factory engine driven fuel pump outlet to the top of the fuel tank to pump air in to pressurize the fuel. it would keep up with the fuel getting lower as the race went on.they used a check valve on top of the tank set at the pressure they needed for the carbs. It was made for crop dusting air planes,spraying liquid on crops .it worked great till the stack injected cars came in.

 

Keep in mind the reason you don't see them as much anymore, a vessel filled with gasoline and vapors under pressure is literally a bomb. Not that I am a safety jackass, it is a little edgy, even for me. And, I'm a guy that will drive with no brakes or with 120 degrees of slop in the steering
Mike

 

Hello,

When my brother and I started our 1940 Willys Coupe build, there were plenty of racers with the Moon Tanks inside of the passenger’s footwell area. It was an approved way to mount the small capacity gas tank. The pressure hand pump came with most of the Moon Tank set ups. The run to the motors were short and the pressure added more even flow of gas to the carburetors or the injectors.

Since the tanks were set up strictly for the drags, not a large amount was necessary. Our 2.5 gallon Moon Tank was perfect for several runs before we had to fill up the tank. Where was the original gas tank on the Willys? (In the back area where it normally resides.) Most coupe racers filled up the tank with water and shut off the gas outlet line. The full tank gave extra added weight to the rear of the coupes/sedans for better traction. But, only if the weight was necessary to fit into the specific class.

Not only did we have the water in the stock gas tank, but we also welded in some steel plates over the rear axle inside of the trunk. The welded in plates gave the coupe less flexible movement during the hard acceleration and some rigidity to the whole structure. Legal only if welded to the trunk floor, not just bolted in place.

The Moon Tank in the passenger footwell area gave the driver direct access to the hand pump, just prior to the final staging on the line. A couple of pumps was all that was needed for the 12 second runs in the quarter mile distance and back to the pits. The 58 Impala always followed the 1940 Willys Coupe to the starting line. It went down the return road to tow the Willys Coupe back to the pits, but, it was fun to drive the Willys Coupe back into the pits with a satisfied smile on our faces, too.

Jnaki
Yes, when we went cruising around after the initial build and fire up, it was a little cramped for the passenger during the 12 mile circuit we created. It took two full gas tanks to complete the trip on our cruises. After all, it was a street legal coupe. Everything was DMV approved for So Cal, including headers capped and run through legal mufflers/exhaust pipes.


Picture this Moon Tank set up inside of most drag racing cars of the late 50s to mid 1960.

The photo shows the Moon Tank and pump inside of the compartment.


But, after August 13, 1960, the tech committees of most drag strips and the Standard 1320 ruling committee decided that the high possibility for in cab explosions would do more harm than good, so it was doomed. The requirement was for a two week time period to move all interior gas tanks and pumps to the rear trunk or to the front of the motor, behind the grille. This took place after our clutch explosion and resulting fire, destroying our 1940 Willys Coupe 671 SBC motor set up.

Most moved the Moon Tank into the trunks with access to the final pumping to be done prior to rolling up to the starting line. But, there were some that liked the access of Moon Tanks sitting outside of the grille shell for direct access by the pit crews or the driver prior to making his run. A silly place for a street legal coupe or sedan used for daily driving. A gas tank for the day to day bumper action on the city streets was not the most logical place to put a gas tank. (looks wise or functionality, certainly not for safety.)

A whole new generation took that “ruling” and created an awful location and look for the next generation of Gas Coupes/Sedans. Drag racing changed in the late 60s and the street legal classes, all got folded and eliminated in the drag racing circles. But, the awful look of the front area gas tank, continues to this day.

As one person’s look and definition of the tank in front: "It looks like a bomb attached to the front, to ward off the traffic… and explode on impact. YRMV

 

How often you have to use the hand pump varies with tank volume, and how much gas is in the tank. The fuller the tank is the less pumps it takes to reach pressure. But that also means you'll need to pump again sooner as you drive and the level gets lower. A lower gas level takes more pumps to reach the same pressure, but because of more air space in the tank it will hold the pressure longer before needing more pumps again.

 

The pressure required raise the fuel is actually very small, perhaps 2-5psi? If you want to do it properly it should be easy to set up a failsafe which vents excess pressure to atmosphere, in addition to a pressure-regulated supply. This kind of system was not uncommon in the 1920s and early 1930s: some manufacturers even used exhaust pressure without incident.

I've developed a fascination with this history, all the cleverness which was applied to getting around the practical unavailability of a reliable electrical system. In 2021 there is something hugely satisfying about designing around the idea that electrics are going to be dodgy and best avoided, especially if we simultaneously embrace the state of the art in materials science as regards seal materials and such.

 

In our local shop, a 1932 Bugatti, 8cyl, 1500cc w/a blower had one. Mounted on the dash.

 

Would suggest looking at 282doorUK’s thread ‘Made A Fuel Tank Pressure Pump’
This is what I was working on just yesterday just need to add some check valves and mounting brackets
Will someday be on my AV8 speedster special