Technical fuel pressure regulator install question

I am running 4 Weber IDF 48's on my 1960 Merc ragtop i am building. I see that Weber only wants 3-4# pressure. I don't think the regulator will be able to feed 4 carbs as far as volume goes. The regulator I have has a very small orfice for the fuel to go through. I an contemplating putting the regulator AFTER the carburetors in a return line. That way their will be plenty of volume to the carbs and the pressure will be maintained by the regulator.

pump--------carburetors -------- regulator ----------------fuel tank

 

If a town is trying to prevent flooding, they typically don't build the damn downstream. But I am no engineer.

 

You only need to flow as much fuel as the motor needs regardless of how big or how many carbs you have. What horse power are you expecting.

 

You could put the regular after the carbs. You didn't mention what regulator you have. In most cases a bypass regulator before the carbs would be better.

 

you could get a better regulator, like the Holley low pressure

https://www.summitracing.com/parts/hly-12-804

for example

 

I do have the Holley regulator. Can I just mount it before the carbs with no return? I'm using a 14# electric fuel pump

 

Yeah, it's a dead head regulator.

I have the higher pressure version (the only difference is the strength of the spring) in Plan II, which makes about 700 hp. I don't think it'll be too restrictive for you.

 

It's a 4.6 Lincoln 4 valve with 4 webers and twin turbo with a t45 transmission. thank you for the help

 

The specs for regulator are
Notes:
Maximum inlet pressure is 7 psi.

John

 

The last thing you want on a boosted motor is to have a fuel supply issue. If it was mine, I'd want a regulator with a return line - that would be the best way to go. I'm not sure Holley makes a low-pressure regulator with a return line - seems when I researched this before, I had to go with another company???

 

I've never worked with Webers on a boosted application - are they upstream of the turbos? Can you even do blow-through with them? The configuration can change how you have to think about fuel-pressure regulation.

 

Make sure to buy the GOOD holley regulator. The cheap ones and just that, cheap. I just had to bypass one of the cheap holley regs on my 60 f100. They make a billet one that has really good reviews.

 

Sure can!

 

this is how I set up my 3 holley - 1&1/16” - Fuellab bi-pass regulator set up how they say to set it up,
Edit : but I don’t have twin turbos and missed that point in the original post.

 

Yes you can, a return line is not required for these low pressure regulators.

 

@Birdman

There’s some good info right there and should looked into before just using the regulator suggested.

 

Holley 1-4 lb regulator doesn’t want more than 7psi pressure into it according to Holley website.
Malpassi make a good fuel deadhead/ blocking regulator. - although I am unsure of their upper limit requirement for pressure. It was recommended to me by our local Weber specialist for my situation, although my ‘stock’ replacement fuel pump was only putting out 9-10 lbs - edit I don’t have turbos.

 

I still haven't heard about the actual boost configuration? Is this a blow-through or*****-through usage of the Webers? Given that he's boosted, you have to know the answer to this in order to recommend a fuel-pressure regulator.

 

First time I've heard of putting the regulator after the carb(s). It's early, haven't had any caffeine yet, but I'm not getting how in the hell that is going to work. WTF???

 

This is typically done with a 'return line' type of regulator - not a "dead head" one like he currently has. Though I've usually seen this shown with EFI type systems with fuel rails.

On carb systems, the return style regulator is usually plumbed in before the carbs. It doesn't make a lot of sense to me to take a dead-head regulator and turn it into a return device (where the outlet port that usually supplies the carbs is now a return line) . . . but I'm sure some have done it.

 

With electronic injection most OEMs originally used a return line and the regulator was mounted AFTER the fuel rail/injectors. It has since changed but not because it did not work well. They also worked at a higher pressure.
Putting the regulator after the carbs would subject the carbs to whatever variation occurs in the pressure before the regulator can react. Working with such low pressure and with the induction system you described, my concern would be possible starvation of fuel and a subsequent lean condition under boost. Personally, I would want to use some type of fuel system that had higher pressure and possibly an ignition cut off if pressure dropped below a certain level. Thats hard to do when working with a minimal fuel pressure. You could run a higher pressure electric pump and then have the regulator reduce the pressure and have a larger volume orifice on the output side. Plenty of volume that way and less chance of starvation/lean condition.
Also, be sure that the regulator you use is an authentic one and not a knock off copy thats not reliable. Also, you need to check and see how many gallons of gas you need to pump so you know if your whole fuel system is capable of doing that.

 

Remember . . . . going lean under boost . . . . is bad JuJu . . .

 

OK, after a little caffeine and a little time it starts to make sense. You could place a regulator in a fuel rail or log and have it relieve excess pressure from the rail; it could also be used to ensure a minimum pressure is retained in the rail. This would have to be a regulator with a return line to return unused fuel back to the tank. This is really not "after" the carb, it would be more of parallel to it, maintaining a small reservoir of fuel within a range of pressure settings.

 

ShuGotIt Brother!

 

We "sort of" did this on an O/topic V8 carbed touring car, where vapor lock was a major issue.

Dead head lines reduced the life expectancy of the electric fuel pumps, so we used an EFI pump with a "full loop" return line to the tank.
The pressure regulator was basically a bypass check valve that dumped the excess pressure. The EFI pump usually pumps at 43psi but we adjusted the fuel to dump at 20psi which gave good flow and enough pressure to prevent vapor lock.
Up at the carb end we Tee'd off a very short line to another 7psi deadhead regulator adapted directly to the side of a 600 VS Holley [a controlled component]



The best aftermarket pump [at that time] was a Mallory gear type, but hooking this up to a 7psi deadhead resulted in very short life expectancy. [14psi minimum line pressure was needed for preventing vapor lock]
If we used a standard bypass type regulator, to lower the pressure to the carb, it also lowered the whole line pressure below the vapor point of the fuel.
So we needed 2 regulators [one for the carb, and one for the whole system]

All this drama ^^^^ was needed because the "Almighty Powers To Be" decided to ban Avgas for a National Series.
It wasn't fun when your car spluttered and stalled at the start line [and wouldn't start]

 

I've worked on some systems where the fuel pumps utilized controllers to reduce their speed/volume when it wasn't needed (stop n go traffic, etc.). Also, the idea was to reduce the amount of return cycle volume back to the tank - to reduce the heat soak from the constant "loops" to the front and back. I'm not sure if anybody is doing this today (may not be necessary), but I'd probably contact a good supplier like Weldon and discuss your ENTIRE system. You want all the correctly matched components - front to rear. Also, talk to them about boost referencing - whether or not it is needed with your setup.

 

I run the 12-804 and I mounted it on the back of my blower before my three 97 Stromberg's on my flathead. I run 2.5 psi to the carbs and it works well. However (there is always a however) my in tank pump (tanks inc) was producing far more pressure than the Holley reg can handle so in my case I had to run a carburetor, return style, reg to reduce the pressure to 5 psi and then use the 12-804 to further reduce the pressure to the Stromberg's. *****s buying 2 regs but in this case I could not find a single reg to knock down the pressure to 2.5. Also, in the case like mine the return line and delivery line should be the same diameter.

 

There are back pressure regulators...think relief valve and you can return the fuel to the tank...bit it is a different animal than a PRV....but you got the basic picture

I am in the Malpassi camp...that is all I use now and have been nothing but ecstatic with their performance and if you think of it they have a much larger diaphragm than the other mentioned regulators....bigger amplifier for the signal....and they look traditional

 

I have a Malpassi "Filter King" on my 32 Cabriolet - works great. The only thing to note is that you sometimes have to adjust the pressure in Summer or Winter (if it gets cold) - probably because the diaphragm performs differently depending on the temperature extremes. The other nice thing about them is that they have a fuel-filter onboard.

They have both a dead-head style and a bypass style - though their fuel ports are small (1/8" NPT). They are fine for a lower-horsepower situation, but I would not want to be running a single one on a high-horsepower situation - volume could surely be an issue. As we don't know much about the OPs engine, blower, carbs, etc - still can't try to recommend which setup is best for him. He seems to have gone away . . .

Depending on the horsepower of his engine, would still go with the bypass (they call it a converter) style - so you're not dead-heading the electric pump.

Converter - Bypass: 30048CONI67 (officinamalpassi.it)

Here you can see one mounted - between the oil filter and the fuel pump stand:

 

this, I didn’t know.
I bought a dead head one, but which looks like the one that you posted above.
Are the bi-pass ones the same or different shape ? - thanks !

I also tried to re-clock mine, but couldn’t get the top off, - guessing that the screws are glued in with locktite or similar.