Fuel pump
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Hotrod46
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I have 3x2's on both my 350 powered T(5 years) and the 383 in my 46(15 years now). I run electric pumps and pressure regulators on both cars.
The main reason is to be able to prime the carbs after they have been sitting for awhile. Today's gas seems to evaporate quickly and I find my cars get dry in just a few days. Grinding and pumping on 3x2's is a super quick way to flood the engine. Remember, what you really have is a mechanical secondary 6 barrel triple pumper and they can dump a lot of fuel. The old "hold it to the floor and grind on it" trick to clear a flood doesn't work well with trips, too much air to be able to start. At least it's never worked for me on these cars, not even once. If I do screw up and flood one, I just walk away for awhile and let it evaporate.
I also have electric chokes on both cars. My starting procedure is to prime the carbs and tickle the throttle just enough to set the choke. Usually starts right up with no drama.
I did have a mechanical pump on my 383 when I first built it and it certainly worked fine. I didn't like it for for the starting dry issue and because it was very difficult to get to on that car if it needed to be changed on the road.
If you're running Rochester 2G's, you don't need more than 4-5 pounds of fuel pressure. I'm running 4 1/2 on both cars. What you do need is plenty of volume. I run a Holley red on the 383 and a Carter on the T. I know neither one is listed as needing a regulator, but I wanted to make sure to keep the pressure under control.
BTW - I have oil pressure safety switches and Ford inertial cut-off switches on the pumps in both cars.
Mike
The main reason is to be able to prime the carbs after they have been sitting for awhile. Today's gas seems to evaporate quickly and I find my cars get dry in just a few days. Grinding and pumping on 3x2's is a super quick way to flood the engine. Remember, what you really have is a mechanical secondary 6 barrel triple pumper and they can dump a lot of fuel. The old "hold it to the floor and grind on it" trick to clear a flood doesn't work well with trips, too much air to be able to start. At least it's never worked for me on these cars, not even once. If I do screw up and flood one, I just walk away for awhile and let it evaporate.
I also have electric chokes on both cars. My starting procedure is to prime the carbs and tickle the throttle just enough to set the choke. Usually starts right up with no drama.
I did have a mechanical pump on my 383 when I first built it and it certainly worked fine. I didn't like it for for the starting dry issue and because it was very difficult to get to on that car if it needed to be changed on the road.
If you're running Rochester 2G's, you don't need more than 4-5 pounds of fuel pressure. I'm running 4 1/2 on both cars. What you do need is plenty of volume. I run a Holley red on the 383 and a Carter on the T. I know neither one is listed as needing a regulator, but I wanted to make sure to keep the pressure under control.
BTW - I have oil pressure safety switches and Ford inertial cut-off switches on the pumps in both cars.
Mike
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Thanks to all for the info. I'll probably go with the electric pump.
Screaming Metal
Active Member
What HotRod said! Yes, I have a tendency to run electrical also, that rubbing on the cam just grates on my nerves, its bad enough to have lifters rubbing....While it isn't necessary to have one on a stock motor, if theres any kinda motor reving going on, go with a fuel log, too. While 4 or 4 1/2 won't flood things, its barely able to keep fuel in the line during a really hard launch, as motor rpm increases, lets say, a 1/8 or a 1/4......ooooops......1000ft., romp down the asphalt, so your mainly running off whats in your float bowls.
Run a regulator to keep the pressure to a manageable level, fuel log by carbs, besides looking cool, it gives you a place to mount a pressure gauge so you can see it....
I also run a Hobbs switch with a level sensor(rollover sensor), that way your protected during a wheelie, but will cut pump of car is rolled over, when the motor is off, the fuel pump is off too. I also run a bypass press button to prime the system with, all fused of course.
Use a spring loaded primer button, so you'll have to hold it to work. It left on a toggle, you can forget about it and have a accident....
Run a regulator to keep the pressure to a manageable level, fuel log by carbs, besides looking cool, it gives you a place to mount a pressure gauge so you can see it....
I also run a Hobbs switch with a level sensor(rollover sensor), that way your protected during a wheelie, but will cut pump of car is rolled over, when the motor is off, the fuel pump is off too. I also run a bypass press button to prime the system with, all fused of course.
Use a spring loaded primer button, so you'll have to hold it to work. It left on a toggle, you can forget about it and have a accident....
Do you have to run a return line with an electric pump?
Screaming Metal
Active Member
I'm with Potvin and all those guys, its not worth running the risk of possibility of leaking fuel into the crankcase from a ruptured diaphram.... besides, you can wire up the hobbs switch, helps keep you from flooding when sitting still with the motor off. If you should loose your oil pump, god forbid, it'll save your motor from serious damage....which is a definite plus in my book. No oil pressure, no fuel.
You can do the same thing with the mech. pump, just wire the hobbs to a fuel shutoff solenoid between the pump and carb. I just don't like the mechanical pumps.
They're dependable, and cheap, but I can't get past the rubbing part, since I'm also building motors....also I've seen the weep holes squirt fuel and burn a car down....
You can do the same thing with the mech. pump, just wire the hobbs to a fuel shutoff solenoid between the pump and carb. I just don't like the mechanical pumps.
They're dependable, and cheap, but I can't get past the rubbing part, since I'm also building motors....also I've seen the weep holes squirt fuel and burn a car down....
No return line with carbs. Just an electric pump that puts out at 5-8 psi. No regulator needed unless you use a pump with more pressure, like 15-20 psi. I've had good luck with Holley.
Screaming Metal makes good points; I've seen torn diaphragms on mechanical pumps.
Screaming Metal makes good points; I've seen torn diaphragms on mechanical pumps.
Hotrod46
Member
I've seen a couple myself. Both times gas went into the crankcase. Thins the oil down real good.
As far as the regulator goes, that's just a Rochester issue (pretty much all of them). They just don't like much pressure. Edelbrocks don't either in my experience.
Mike
Screaming Metal
Active Member
As all of us said, yes, its best to have only a 'X' amount of pressure to keep from overwhelming you seat and float. I always run a liquid filled PSI gauge on the log by the carbs on all my motors, where I, the crewchiefs and the driver can see. Or a electrical pressure readout on the dash.
The Mr. Gasket regulators don't cost alot, and sometime don't work as well as expected, but thats what the gauge is for. Sometimes you might have to go thru a dud before you find a good one (regulator).
I run mostly Mallory stuff, since I like their spin on fuel filters ahead of my pumps. On my motor stand I have several regulators mounted, all different colors that way I know which one is set at what pressure. I set them, then leave them set.
On your T, mount a good 5/10 micron filter AHEAD of your pump....this will save it from trash at the service station. And watch for the ethanol laced stuff at you local 'Go-Juice' place....
The Mr. Gasket regulators don't cost alot, and sometime don't work as well as expected, but thats what the gauge is for. Sometimes you might have to go thru a dud before you find a good one (regulator).
I run mostly Mallory stuff, since I like their spin on fuel filters ahead of my pumps. On my motor stand I have several regulators mounted, all different colors that way I know which one is set at what pressure. I set them, then leave them set.
On your T, mount a good 5/10 micron filter AHEAD of your pump....this will save it from trash at the service station. And watch for the ethanol laced stuff at you local 'Go-Juice' place....
Mike
Well-Known Member
Except the fuel in the floatbowl/s, which can keep the engine alive for a lot longer than you might expect.
In this situation, I would recommend using an oil pressure switch to simply ground the ignition. Then, if you lose oil pressure, the engine shuts down, rather than running itself dry. A momentary bypass button for the system can be a bit of a pain, but I still think that is is a much more reliable means of shutting things down. And then you don't have the additional expense of an electrical fuel solenoid, on an engine with a manual fuel pump.
Electric pumps are a lot better than they were a few years back, but I still have to lean toward the convenience of nearly every parts house having a mechanical fuel pump in stock, if you should happen to break down on the road. A bit of a coin toss, to be honest.
Not necessarily true. Regulator design will determine the need for a return line or not. A bypass regulator, which is much quicker at reacting to system pressure changes, will require a return line.
Hotrod46
Member
One reason is to keep the fuel cooler. The gas gets circulated back to the tank and has less time to pick up heat than if it just moved slowly through one line to the carb.
Also some of the big electric pumps rely on fuel flowing through them constantly to cool and lubricate the electric motors.
Mike
Screaming Metal
Active Member
Hahaha....Mike is correct again....usually I wire the hobbs not only to the relay to the pump, but if pressure loss, it kills power to the ign. ;-)......my boo-boo.
Yes, going down the road at 3400rpms and losing the oil pump, yes, you can run 1/2 to2 miles before it starts sputtering, well into spinning a bearing territory or loosing a rod. I usually do both on my own rods. But the oil press. switch mostly helps with flooding, and having to toggle the pump on and off manually, starting and stopping.
Yes, going down the road at 3400rpms and losing the oil pump, yes, you can run 1/2 to2 miles before it starts sputtering, well into spinning a bearing territory or loosing a rod. I usually do both on my own rods. But the oil press. switch mostly helps with flooding, and having to toggle the pump on and off manually, starting and stopping.
Screaming Metal
Active Member
Oil pumps are so reliable and simple, they just don't go out much, but when they do, its expensive. Alot of times, it isn't the oil pumps fault. Most of the failures are the pump mounting bolts vibrate loose, shaft between the distr. gear and pump shearing or twisting,
loosing a oil plug on the front of the block, stopped up pickup screen, pickup falling out of pump body, (not installed correctly),
oil pump bypass spring or pressure spring failure....all of these plus alot more that'll cause your motor to loose oil pressure. Even trying to tighten up a loose distributor shaft can cause downward pressure on the pump shaft and cause it to fail.
Theres not a whole lot to go wrong with the pumps; a housing, 2 gears or rotors and a shaft, 2 springs, and cover plate. When I blueprint a motor, the oilpump is a major component. You gotta have those clearances just so-so, if you do, you'll almost never have a failure.
Most oil pressure related failures are at low enough speeds to avoid too much damage, but once you've had it happen to you, you'll NEVER want it again. The breaking of a crank, a rod, or a hole thru the side of the block is a very sickening sound. The little Hobbs switch that used to be used on the Vega's are perfect, and are not expensive at all. And all you have to do is feed your ign. POWER IN to one side, and OUT the other side to the ign. and your protected. Simple....
But when you wire it to your fuel pump, use a relay. Some of those pumps will pull alot of juice. And if you run both...your very well protected against a myriad of problem....
loosing a oil plug on the front of the block, stopped up pickup screen, pickup falling out of pump body, (not installed correctly),
oil pump bypass spring or pressure spring failure....all of these plus alot more that'll cause your motor to loose oil pressure. Even trying to tighten up a loose distributor shaft can cause downward pressure on the pump shaft and cause it to fail.
Theres not a whole lot to go wrong with the pumps; a housing, 2 gears or rotors and a shaft, 2 springs, and cover plate. When I blueprint a motor, the oilpump is a major component. You gotta have those clearances just so-so, if you do, you'll almost never have a failure.
Most oil pressure related failures are at low enough speeds to avoid too much damage, but once you've had it happen to you, you'll NEVER want it again. The breaking of a crank, a rod, or a hole thru the side of the block is a very sickening sound. The little Hobbs switch that used to be used on the Vega's are perfect, and are not expensive at all. And all you have to do is feed your ign. POWER IN to one side, and OUT the other side to the ign. and your protected. Simple....
But when you wire it to your fuel pump, use a relay. Some of those pumps will pull alot of juice. And if you run both...your very well protected against a myriad of problem....
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Mike
Well-Known Member
Along with the fact that a bypass system recovers much more quickly from a pressure drop, because all of the fuel in the system is all still moving.
In a dead headed system, when the regulator reaches its pre-set pressure, it closes, the fuel column stops moving and then the pump starts bypassing fuel internally. In most vehicles, the fuel supply is located at the rear of the vehicle, so under acceleration, not only is the fuel trying to over come the regulator pressure setting, but it is also trying to overcome its own mass. People always want to run larger supply lines from the pump to the front of a car, but the larger the line, the more fuel in the column and the more fuel in the column, the more mass it has. It's Newton's Second Law -
With a dead headed regulator, you pull to a stop, the motor drops to idle, the fuel pump catches everything up to fuel demand, the regulator closes and the pump starts bypassing. If you stand on it, there is a pressure drop, the regulator opens, the fuel column starts trying to overcome its own mass, whilst the pump stops bypassing and starts moving fuel forward again. The fuel that was bypassing within the pump has picked up heat in that process, so it has also lost density, which will play a small effect in your carefully designed fuel metering, up at the business end of things.
None of those things occur in a bypass system, since the fuel column is always on the move. Yes, mass of the fuel column comes into play, but now we are leaning back onto Newton's First Law -
So the mass of the fuel must overcome the unbalanced force of acceleration, but since motion is already established, the mass of the column is working with you, rather than against you.
And I suppose whilst being here and in the thick of it, now is a good time to clear up another common myth and misunderstanding. Joe Schmoe has a single Holley 4 bbl on his engine and he decides to swap that out for a dual-quad combination. More carbs will mean more fuel supply is required, aye? Johnny Tiresmoker is sitting there, nodding his head, because there is no way that same fuel system can keep up with double the carbs.
But Johnny doesn't know beans. Actually, Joe has just reduced the load on his fuel system, because his engine now has four float bowls (think: reservoirs), instead of just two. The mere act of bolting on another carb didn't change the motor's fuel requirements by a single ounce. One carburetor or twelve, the motor has a finite fuel requirement, so there goes another fallacy on the fly.
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