221ci fuel flow?

[ajmac]

I would like to know the fuel flow requirements for a 221ci 81A. I am fitting an electric pump with output pressure of 2.5-3.5 psi but in that range there are various specs of pump for various fuel delivery rates, I need to know which will meet the V8s requirements and I can't see anything in the original manuals about the spec of the original mechanical fuel pump.... I will be fitting a British SU diaphragm pump and have made a steel plate to replace the diaphragm in the mechanical pump and removed the valves so that the engine will look stock with mechanical pump still attached.

 

[deuce lover]

Max 2.5

 

[BUBBAS IGNITION]

Typical fuel volume delivery is .5 us gallons per minute or a pint in 15 seconds.
Just about every thing will operate well with this spec..

 

[Bluebell]

Alastair, go to Vanpelts tech site. Have a look at "fuel and carbs" another good one is"I.D.your v8 carb"
During the warit was found that "fan wash" effected the float level in the carb, so the vent was moved to the other side of the carb. Later it was internal.

 

[Mike in AZ]

fuel regulator and gauge to make sure of pressure??...good luck....Mike

 

[Bluebell]

A friendly piece of advice to a patriotic Britain.
as sensitively as I can, ditch the S.U. pump. Leave it to the Austin Morris Jag fraternity. I have rebuilt a few, years back, but would skirt around them in this day and age.
I recall you are not going to run with the original Solex, because the commercial carb performs much better. Why then would you run the Skinners union pump?
There are many modern electric pumps.
In line with what Mike said, I will be running a pressure regulator, in my carrier.
Just my humble opinion.

 

[JWL]

Although our Flathead engines are among the least efficient from a BSFC(Brake Specific Fuel Consumption) viewpoint, it is safe to figure 1/2 pound per hour, per HP. The 221 engine will make something less than 100 HP at maximum output. So any pump which supplies 50 gallons per hour at 2 lbs. pressure, at the carb float, will easily and safely handle the requirements.

 

[G.M.]

You can pump all the fuel you want but the flow into the carb is controlled by about a .100 hole in the needle valve inlet. It makes me laugh when I see people recommend 5/16 or 3/8" fuel lines. I happened to buy some heavy wall copper tube with a .125 ID. I discovered this when making a pump to carb fuel line. I decided to try it and it's been on the engine 3 or more years and never starved for fuel. 1 1/2 lbs pressure is all you need BUT with this new gas boiling in the pump increasing to 4 lbs COLD pressure from the stock pump is required. Why, the pressure comes down as the pump gets hot from the intake manifold and excessive heat at the rear of the engine from exhaust manifold and very little air movement. As the pump heats the pressure drops and vapor lock starts with this gas that boils at 130. The little extra pressure pushes the fuel, when the pressure drops below 1 lb fuel delivery problems start. Running at highway speeds the problem is reduced because more fuel is running through the pump. This cooler fuel cools the pump, in real hot weather fill the tank when you start on a trip, not the night before.
Don't run the tank below 1/4 and refill. The gas buried in the ground tank is cool. G.M.

 

[FlatheadTed]

Stay with the proper Ford pump I have just removed the electric pump pictured on the running board ,of this imported car ,it didn't work I believe this is a common conversion I can see why you need the tank above half full as it needs a gravity feed .I personally prefer to set my pressures at maximum 3lb other wise it could possibly overcome the needle valve .

 

[FlatheadTed]

These have been modified with hand tickler you will find plenty over there

 

[ajmac]

Thanks for all the replies but I still find it hard to believe that the original mechanical diaghphram pump supplied 50 gallons per hr. is there an original spec for the pump?

Lynn,
SU pumps are 10 a penny in the UK an with the solid state mod kit from Burlen fuel systems its perfectly reliable - gone those troublesome points!

 

[FlatheadTed]

The stock mechanical pump at idle pumps One pint a minute = 7/1/2 gal an hour .

 

[Bluebell]

GWL, with all due respect, I would disagree with some of your statements. In particular, I wouldn't use copper pipe as a fuel line on a flathead, because it conducts heat so fast. I guess it all depends on the climate you live in. I thought in Florida, it would cause you problems.
Alastair. I'm obviously out of date with the S.U. I didn't know they had gone solid state.(I started avoiding them, about 30 years back)
Ted, the war time pump, for military Fords, had a priming lever, and drain **** as original. (As you say the ones you show are common in N.Z and probably in the U.K.)
Different Ford flathead v8 carbs, have different maximum pressure specs. (listed in the above mentioned Vanpelt info)

Alastair, I have no doubt that you know all this stuff, but will mention it for the benefit of others:

The reasons for going away from the original pump:
1.Risk of Vapour lock.
2. the risk of diaphragm failure, leading to oil dilution (and subsequent engine failure. (this is my main reason, with the high aromatic fuel)
3. slight drop in horse power.

I would install an electric pump, for the above reasons, along with ease of starting (after sitting)

Mechanical fuel pump volume is dictated by the pump stroke.
Delivery pressure is 100% dictated by the spring under the diaphragm.
To get a different delivery pressure, change the spring