Additional electric fuel pump setup

[Saltcityslant]

Hello,

I've installed a /6 in my classic truck, (1936 Dodge truck) and I am building the fuel system. I have my float, hard line to an inline filter, and then I was going to run it to a fuel pressure gauge right before the carb of the slant. Should I add an electric fuel pump in-between the filter and the block fuel pump? Should I just make a plate of steel to cover where the block pump goes, and use a regulator and gauge at the carb, and use an electric pump to power the whole system? I'm curious if it would increase my reliability or if it's an unnecessary modification. I have a cam to break in on this motor, and I would like to avoid as many cranking cycles to get it to started as possible, so I don't accidentally wipe a lobe in the process. I don't know how long the factory pump takes to get fuel from the tank to the carb. If anyone has any advice to make this work better, I'd appreciate the input.

Thoughts?

Thanks,

Edit: On a slant six, what is the factory line width? I was just going to go as small as possible, I'm not reaching for super high horsepower numbers. I've got a big lift cam, with four barrel intake and carb, crank and rods are balanced from the previous owner. I'm running a 3.40 rear end with 33 tires and an 833 OD. If that makes any difference. Thanks pros

 

[67Dart273]

Many guys don't like electric. With today's fuel an electric PUSHING which they ALWAYS should do, AKA mount it low near the tank, helps prevent fuel boil/ vapor lock

You could leave a mech in there but in today's world, obtaining QUALITY mech pumps is difficult. What happens when it leaks into the crank case?

This is my personal opinion, I would research and buy a decent electric pump that does NOT require a regulator for a carb, and mount it near the tank. If the carb protests, you can add a regulator

I used to think Walbro pumps had a fair reputation.

Using your head and mounting the pump on rubber helps silence the thing. All metal lines to and from the pump will transmit noise

 

[Saltcityslant]

Many guys don't like electric. With today's fuel an electric PUSHING which they ALWAYS should do, AKA mount it low near the tank, helps prevent fuel boil/ vapor lock

You could leave a mech in there but in today's world, obtaining QUALITY mech pumps is difficult. What happens when it leaks into the crank case?

This is my personal opinion, I would research and buy a decent electric pump that does NOT require a regulator for a carb, and mount it near the tank. If the carb protests, you can add a regulator

I used to think Walbro pumps had a fair reputation.

Using your head and mounting the pump on rubber helps silence the thing. All metal lines to and from the pump will transmit noise

This is excellent. Thanks for the detail and timely response.

I will go with an electric setup, I think it'll make my life easier, I already did the 12v alternator conv on the slant. So, does anyone know roughly what GPH the slants prefer? I assume it's probably like 1-3. Thanks for the tip, it didn't occur to me that those fuel pumps can leak into the engine, and that's the last thing that I need.

 

[MadScientistMat]

Whatever I would do, I would only use one fuel pump. My preference for an ordinary carbed slant six would be a stock type mechanical pump.

If I did use an electric pump, I would put it close to or inside the tank. Run a pre and post pump filter, and my preference would be an external return style (bypass) regulator. A pump with no regulator - unless it's built in - means the needle valve at the carb is the regulator, and it doesn't do nearly as well as a purpose built pressure regulator. Bypass type regulators do not work the pump as hard as deadhead regulators.

 

[toolmanmike]

This is excellent. Thanks for the detail and timely response.

I will go with an electric setup, I think it'll make my life easier, I already did the 12v alternator conv on the slant. So, does anyone know roughly what GPH the slants prefer? I assume it's probably like 1-3. Thanks for the tip, it didn't occur to me that those fuel pumps can leak into the engine, and that's the last thing that I need.

The mechanical pump worked on Billions of cars for a century. Install an electric if you choose but it really isn't necessary. Make sure you install a regulator somewhere near the carb and no more than 5# pressure. Make sure the circuit is fused and think about installing some kind of a rollover switch just in case.

 

[sabre67]

If you go electric Carter P sreies pumps are nice and quiet,good quality

 

[French demon]

The mechanical pump worked on Billions of cars for a century. Install an electric if you choose but it really isn't necessary. Make sure you install a regulator somewhere near the carb and no more than 5# pressure.

Hi
Little related reflexion :
My old (read : original) mechanical fuel pump still delivers between 5 and 5.5 psi.
You're right, I also think that an electric pump isn't necessary to feed our old good /6

 

[TT5.9mag]

For reference, when you fire the engine for the first time, don’t rely on any of the fuel pumps to fill the carb while cranking. Get yourself a small bottle of fuel and fill the carb bowls through the vents.

 

[Oldmanmopar]

Do yourself a favor and put the regulator on the return line to the tank using a bypass style regulator.

Holley 12-881 Holley Carburetor Bypass Style Fuel Pressure Regulators | Summit Racing

 

[toolmanmike]

Hi
Little related reflexion :
My old (read : original) mechanical fuel pump still delivers between 5 and 5.5 psi.
You're right, I also think that an electric pump isn't necessary to feed our old good /6
View attachment 1716377979

Nope, not really needed for a slant 6.

 

[slantsixdan]

Use one or the other, but not both. Mine's another vote for a thoughtfully-chosen stock-type mechanical pump. If you choose to use an electric pump, read this. If you choose to use a mechanical pump, pick it carefully. New \6 fuel pumps tend to be much poorer quality than we used to be able to get. If you go too far the other direction, old fuel pumps pose risks as well—rubber doesn't react well to age, and some of it doesn't react well to alcohol in the fuel. There is no guarantee, but I had consistently fine results buying and using NOS AC № 6972 fuel pumps, even with ethanol in the gasoline. Cheap and easy on eBay, such as this.

 

[Bewy]

Use the Carter P4594 elec pump. And use it on it's own.....It has a built in regulator; just a single line from pump to carb needed.
The most reliable of the aftermarket elec pumps because the fuel circulates through the elec motor section.....which lubes the brgs & keeps the motor cool.
With most of these cars no longer daily drivers, & therefore sitting for long periods without starting, the elec pump is the way to go. I know of a person who had a 4594 on his daily driver for 19 yrs! He replaced it.....Not because it failed but because he thought it had earned it's 'retirement'.

 

[RustyRatRod]

There's absolutely no need for an electric pump on a slant 6. Hop on ebay and search part number 4880. Those are good pumps. You'll only find them NOS or used, but I wouldn't buy used.

 

[Dave999]

standard here
if you have vapour problems fit a phenolic spacer and heat shield under the carb...
i have both because i have carbs where the base of the fuel bowl practically sits on the header pipes, not had a problem since i put 1/8 inch of phenolic spacer in and a metal shield under.
its potentially a lack of fuel in the business end of things. nothing in the bowl no starting until it fills.
any vapour in the line to the carb compresses and vents under action from the pump pretty quick. vapour compresses, liquid fuel does not, the pump shoves any vapour through quickly, what looked like a fuel filter full of vapour quickly fills .
so keeping the bowls full is key.

a standard pump is a good sucker and a good pusher, self regulates based on RPM...i wouldn't want to give that up...

id need a regulator and a return if i went electric


if you are vapour locking in the line from the tank
how close is it to the exhaust? or is it clamped to something that is heated by the exhaust?
do you have a tank vent or vented cap missing from the set up?
vacuum on this side of things promotes evaporation makes the fuel gas off more...

the standard pump will pump vapour with little detriment to its life, it will do it quite well considering its not designed to really do that. It will eventually suck fuel from the tank. that's the beauty of essentially two 1 way valves and a rubber bellows.....
an electric pump will quickly overheat if left to pump vapour for long enough.. it uses the fuel for cooling and lubrication it it will not, when trying to pump vapour provide much if any incentive to get fuel flowing from the tank again.
there is a reason the OEMs went to In tank pumps......can't pump vapour if its submerged and less likely to overheat.

a standard pump can make an unvented tank start to buckle and collapse, you will hear the air suck in as you loosen the cap, fix that problem if you have it .... they suck good...

Dave

 

[Bewy]

The Carter external elec pumps [ except for # 4601 ] do not need an external reg, they are internally regulated. I have used Carter elec pumps on all my cars since the 1970s. The pump on my current ride has been on about 25 yrs, driven weekly.

The decision on an elec pump should depend on two factors:
[1] Do you want to put up with vapour lock? You do not get VL with a pusher elec pump.
[2] The usage pattern of the car. I would say if the car gets driven up to 3 times a week, mech pump is ok. If driven weekly, or longer periods between drives, use the elec pump. The fuel evporates over time & with a mech pump, you have to crank the engine to fill the float bowl; while you are doing that, the pistons are going up/down in dry bores...& bearings getting minimal lubrication; not good for longevity. 'Course, you could prime the engine the engine by removing the air cleaner lid & pouring fuel down the carb bore, hoping that is enough to get the engine started......might be a bit inconvenient on a freezing cold winter morning....
On the other hand, you get an instant start with an elec pump....

 

[slantsixdan]

Also review the fuel line mod with respect to your engine-bay fuel line configuration.

 

[slantsixdan]

Hop on ebay and search part number 4880. Those are good pumps.

That number was used for a lotta years by a lotta brands; there is no guarantee that a pump under number 4880 is good, bad, or indecent. Y'gotta be a lot more specific and p'ticular and picky than that.

 

[RustyRatRod]

That number was used for a lotta years by a lotta brands; there is no guarantee that a pump under number 4880 is good, bad, or indecent. Y'gotta be a lot more specific and p'ticular and picky than that.

I don't know what brand they are, other than they were in "Blackstone" fuel pump boxes and each has cast right into it "Made in USA" and are the rebuildable style pumps. I have like 4 of them I got in Blackstone boxes a couple of years ago. Got them for like 15 bucks each.

 

[BillGrissom]

I have an e-pump on my 1964 slant. I recall the block-off plate is the same as for SB and BB, so easy to source. Might have had to slightly grind off one side to sit flat, at least on one of my Mopar engines (also have SB and BB, all w/ e-pump). I installed an EFI-type pump since hope to someday convert from carburetor to TBI or MPFI. For that, I will install the Corvette filter/reg (outputs 56 psig), but for now have a filter w/ return which has close form factor and same quick-release fittings so could easily swap back to the filter/carb. I have just an open line running back to the fuel tank from the filter vent. That is a 1/4" stub at the tank level-sensor, which builds 10 psig back-pressure at the pump flowrate. Too much for the carb input, so I also have an inline "pressure-reducing" regulator (Mr. Gasket type rotary dial) to drop to 3 psig and a pressure gage to read that.

Could also use a "back-pressure regulator" (think "relief valve") at the carb, which has a return (overflow) to the tank. I have a Holley one on my SB. That is the type of regulator the Corvette filter/reg is and also the regulator in a power steering pump.

I mounted the e-pump in the engine bay in all 3 of my 1960's Mopars, down low on the front sub-frame. My first pass was a Holley Pro-jection TBI on my 1965 Newport 383. I first did as Holley suggests, mounting it close to the fuel tank on the rear frame rail. It made a bothersome noise there which you heard thru the rear seat, even after trying to isolate it on rubber mounts. When I tested the flow out of the supply tube in the engine bay, the fuel just pours out, so hard to imagine that could cause an appreciable restriction for the pump suction. It is also only ~4 ft further than at the rear frame rail. Even less concern since I ran 3/8 tubing for supply since used the existing 5/16 tube for the return. If a smaller "carb pump" (not positive displacement like an EFI pump), you don't require a return line, though many do since they like a vented filter to send any vapors back to the tank. I can only barely hear the pump mounted on the front frame rail with engine off, which is good to assure it is running before turning the key to "crank". Actually not on my slant since I installed the 1970's Chevy oil-pressure sensor which is wired to only actuate the pump when oil pressure is up or the starter is actuated, for safety to turn off the pump when the engine dies.

Photo of my slant. The e-pump is near the firewall. The filter w/ return is mounted where the OE coil was (use GM e-core coil on inner fender). If using an EFI pump, you also need a rough filter on the suction side. I use a 3/8" metal carburetor type. 2nd photo is my 1965 Dart w/ similar fueling. The Corvette filter/reg in that photo.