Webber Fuel Regulator

The round chrome ones that you dial the pressure by clicking the dial up and down are leathal.

They are just a spring loaded diaphragm and tend to stick wide open BESIDES developing leaks through the case.

I use the Holley red regulator. It is factory set at 3-4 psi so you just install it and leave it alone.

In an interesting and related thread I was following on factory 289 FIA and USARC Cobras, Shelby didn't use a regulator. They ran a single fuel line from a single mechanical pump to a fuel block with four nipples and then an individual fuel line to each carb.

That sounds scary to me but apparently works because the pump under those conditions can't pressurize the carbs to the point of flooding.

I think once you introduce an additional pump like a electric fuel pump, you need to show caution and monitor the fuel pressure at the carbs as well.

This guy here, http://www.timsroadster.com/html/tuning_webers.html, took a different approach.

I've run his set up by a few knowledgeable engineers and they are concerned that this set up is using the fuel tank to cool the fuel in the system by returning hot fuel to the tank.

It just so happens that it would be relatively simple to plumb it into a Pantera using the original integral fuel pick up as a return and using the new type of pick up that is on the fuel gauge sender as the supply/pick up.

Having said that I don't want to be the one to test my fuel tank as a "heat sink."


The Holley works ok for me, so "if it isn't broken, don't fix it."

Here's a picture of it with the carbs out on the "bench".

Here it is on the car. Changed the orientation slightly but is located well there. Very accessible. Tucks in well away from the headers.

Thank You PD, that's what I needed to know.

I am with you on the heating of the fuel. The exhaust next to the tank is already a good start.

PD, does the red holey use a return line?

Is this the right one?

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

That's the fancy polished one. Just remember it's set low.
The Holley system is red for low, blue for high pressure.
No return line necessary.

See that link on tuning Webers. It turns the tank into a heat sink.

I guess it's ok with a full tank but what happens when there is only a couple of gallons in there and you are shooting "hot" fuel in the tank?

Answer: I don't want to find out.

All I can find is the adjustable regulator. Do they still make the fixed regulator? Do you have a part number?

You found the right one. It is going to come preset for European carb pressure which is the 3-4 psi range.

It is stating the range in which you can adjust it is 1 to 4 psi.

Just hook it up. Pressure the system and check it. Should be right at 3 with one pump 4 with 2 pumps.

You can run the Webers up to 4.5 or so with no issues. That is usually what the pressure gauge will show as soon as you shut the hot engine off. The fuel pressure rises because of the heat sink effect through the engine, into the manifold and up through the carbs.

I would recommend highly though changing out the original needle and seat to the Gene Berg glass ball needle and seat. Those are good for over 10 psi so they add a needed safety margin.

They also virtually eliminate the peculating of fuel and carb fuel boil over this set up is notorious for on a hot engine that has just been shut off.

They are not cheap though. $20 each last time I bought them.

This is a better shot of the regulator installed.

Doug are you running an air/fuel ratio gauge? I see you have an O2 sensor plumbed into that right header collector

Yes. That WAS the plan. Problem is they are close to useless with Weber carbs.
They seem to defy that type of analytic logic?

It will constantly read crazy rich. It won't agree with the plug readings and the response of the car.

I probably will just plug the port in the collector but I am stubborn and have not given entirely up on that yet.

It has to get in line with other priorities though. It does not have a high one.

As a result, and this is just my opinion and I am not lecturing, people that say the Webers were dialed in on the dyno I have serious doubts about their functionality.

Particularly after being approached by owners saying that they paid a small fortune for it and the car doesn't run for crap.

I had a guy come to me with a 427 Cobra Continuation car that was tuned by Hoolman-Moody and ... you've got to be kidding? He was right. It ran like crap.

No Webers are old old school. You go at them with a enough jets and air correctors to fill the upper deck at Yankee Stadium and a good clear sunny spring weekend and you'll get them where they should be.

Then if you want to measure what the oxygen sensor says, be my guest, but it won't make much sense at all.

Interesting PD. I have an O2 on mine plumed to the dash. The O2 is closer to the heads though and is running off individual runners; not the collective. There is a port on each primary.

When I ran the engine on the test stand I worked on getting the carbs balanced and the idle tuned. I was able to use the O2 with believable results. I'll see what happens when I get it on the road and actually run it under load.

I don't know really. Judging by previous experience, probably misinterpretation of the data on my part.

What I saw is that what shows as being the correct idle mixture on the "machine" does not work on the car.
I think it is that the idle circuit is also the middle circuit all the way up to about 2,800 rpms.
That makes that entire 1000 to 2800 range to lean if you try to clean up the idle.

All that was important "back when" is that the car ran at idle. That's all. It is a racing setup. It is t unable enough to make it streetable within a loose interpretation of the term streetable.

I have a dyno test result somewhere here that was done by Shelby on a 289 comp engine with Webers. Their idle is the same as mine and the main is much heavier.


If too lean at idle the engine will backfire incessantly at either the opening of the throttle or closing of the throttle.
I have blown out mufflers on closing the throttle because the idle circuit was too lean.

Mine idles leaner that a Holley 4779 but not a whole lot less.

The Holley will smart your eyes at idle. The Webers don't. Maybe they do and I'm just getting insensitive to it now?

I do want to try a 60f/80a idle combination and see what that does. I am told that it works but I have not tried it.

The last time I tried 60's was when I blew out the muffler baffles.
The case looked like a bomb went off in them with the seams split open.

I'm at 67/120s now. It's a heavy idle but the power is right all the way into the transition. The 67s have to be drilled out of 65s.

I hate playing with the idle circuit too. When you increase or decrease the size of the idle fuel jet, it effects the idle rpm. The idle set screws become unresponsive at some point and you can't get the car to idle under 1,000 to 1,100 rpm with 70 idle jets.

One thing with these carbs is that I am always influenced by what someone else has said they tried and thought worked and you can always go back and try another combination.

So far I always seem to come back to where I started off though.

You really have no collectors on those headers.
I don't know how that effects everything at this point. Also where you read the richness in the exhaust will likely effect the level. The collectors do have an effect on that just from scavenging alone, even at idle.

I don't know which is better to read. Probably doesn't matter as long as you use a constant location.

These are also carbs. There are some variables you are just not going to be able to tune out unlike with fuel injection.

It is an analog system vs. digital. Apples and oranges.

I reflect on life and what gets me up in the morning; the things I enjoy in life. It is rarely the ending but more the process and discovery.

I need to run it in the car to really know more which is still a little ways off. I am looking forward to playing with it albeit good information or useless.

One thing I do remember from when I ran it (and I have noted this in everything I put the O2 in), it was not so much the actual F/A ratio was relevant as much as it was learning where the targets are for the application.

For instance, on the MG it shows a lot richer then I would have expected but it's irrelevant. I know not only where it needs to be based on how the car runs but I can also see trends which cause the engine to fall flat, lean or rich which allows me to address the problem.

So I guess what I am saying is, and I know I am preaching to the choir here, the actual number is different for application and engine and said numbers don't hold true across the board, but discovered numbers do hold true to the application.

I have run my hand held on the tractor, misc. cars, all run something different. I have one installed in the MG behind the radio delete plate and I love it. I am looking forward to playing with it in the P car:

What? No radio?

Nope.

Panteradoug , you are a brave man running Webbers

It's a thin line between bravery and foolishness. Who's to say which is which?

... better late then never ... I always use the Holley Regulators ... their electric fuel pumps ? well they leave something to be desired ... but that's a conversation for another day ... I sold my webers and Ir EFI intake probably a too soon ... before i ever got to use them ... but personally I like the EFI FUEL set up where you have a regulator and then run the fuel across the rail and then at the end another regulator to dump fuel back to the return to the fuel tank, but this is with high pressure 50 - 60 psi. I guess the low pressure you would be running with webers 4 or 5 psi ? would require very precise regulators with a differential of 1-2 psi. In theory a return back to the tank should not be needed ... with either because with the absence of flow pumps dead head ? But I think on the webers ... correct me if I'm wrong ... some fuel seems to leak past the needed valve and seat and flood the motor ? A very fine precise regulator .. low pressure and a return line to the tank would work ... i'm not sure where you would find something like this ?

Ron

aeromotive makes top of the line parts
;


http://aeromotiveinc.com/products-page/regulators/

quote:

Originally posted by accobra:
But I think on the webers ... correct me if I'm wrong ... some fuel seems to leak past the needed valve and seat and flood the motor ?
Ron

Yes, you are correct BUT JUST with the stock needle and seat. With the Gene Berg glass ball needle and seat, no. They will hold I'm told 20 psi.

What happens with the Webbers is that when the engine is running it will hold 3.5 psi. When you shut the engine off, the pressure will rise to 4.5 psi. At least that's the highest that I have seen.

That seems to be what the issue is with the stock needle and seat. It can't hold that pressure and the carbs overflow.

In that situation, they seem to peculate the fuel like a coffee pot on a stove.

The pressure regulators seem to have a +/- of at least 1 psi. They all use a spring loaded diaphram as far as I know.

Even on the EFI engines I have here the pressure varies according to the pressure gauge. On the FI cars my pressure varies 10 psi or +/- 5 psi.

What is effecting that I think is the variation of the bi-pass valve that returns fuel to the tank.

This guy is using a return line to the tank from the Webers and the pressure regulators is at the end of the carbs before the return to the tank.

http://www.timsroadster.com/html/tuning_webers.html

He has 5,000 miles on the setup and it hasn't self destructed yet but it defies logic of my thinking. Good thing I don't need to make a living doing plumbing and risking my reputation on it?

Aeromotive ... nice stuff.

The plumbing part is inherently in my blood ..

.... So the pressure increases .. from the heat ?

A simple relief valve with a return line to the tank ?

Ok i checked out the Link ...exactly .. setting it up like and EFI system ... perfect.

these are the fuel lines on autolite inline on my 429scj ,the brass cylinder is a pressure regulator w/ bypass jet /pill from rons racing products. designed for carbureted engines w/ belt driven pump. i am using it w /a holley mechanical fuel pump. maintains 4 psi, unused fuel returns to tank . helps keep fuel cooler under hood.

OK. This discussion brings up two more subjects that I see.
1) on Tennessee Tims plumbing system with the Weber carbs and a return line to the tank, how do you protect the carbs from receiving more than 3-4 psi of fuel if the regulator is behind them and not in front of them?

2)considering that we are returning hot fuel to the tank with the return line, how do you protect the tank itself from being susceptable to a flash explosion? Particularly considering that liquid fuel under pressure is going to have a tendency of atomizing, i.e., mixing with the air into a combustible mixture?

This is what I was saying about using the fuel tank itself and it's contents as a heat sink.

I understand that the EFI systems use this but I don't just go and presume that all is well and good.

What happens when the tank is nearly empty and you are spraying hot fuel back into the tank? The Pantera tank is in VERY CLOSE PROXIMITY to the exhausts?

quote:

Originally posted by PanteraDoug:
OK. This discussion brings up two more subjects that I see.
1) on Tennessee Tims plumbing system with the Weber carbs and a return line to the tank, how do you protect the carbs from receiving more than 3-4 psi of fuel if the regulator is behind them and not in front of them?

2)considering that we are returning hot fuel to the tank with the return line, how do you protect the tank itself from being susceptable to a flash explosion? Particularly considering that liquid fuel under pressure is going to have a tendency of atomizing, i.e., mixing with the air into a combustible mixture?

This is what I was saying about using the fuel tank itself and it's contents as a heat sink.

I understand that the EFI systems use this but I don't just go and presume that all is well and good.

What happens when the tank is nearly empty and you are spraying hot fuel back into the tank? The Pantera tank is in VERY CLOSE PROXIMITY to the exhausts?

I guess I would question where the additional heat is coming from? The engine? If the regulator is away from the engine would it make much difference?

It could give you the opportunity to run a fuel cooler to reverse the process?

quote:

Originally posted by comp2:

quote:

Originally posted by PanteraDoug:
OK. This discussion brings up two more subjects that I see.
1) on Tennessee Tims plumbing system with the Weber carbs and a return line to the tank, how do you protect the carbs from receiving more than 3-4 psi of fuel if the regulator is behind them and not in front of them?

2)considering that we are returning hot fuel to the tank with the return line, how do you protect the tank itself from being susceptable to a flash explosion? Particularly considering that liquid fuel under pressure is going to have a tendency of atomizing, i.e., mixing with the air into a combustible mixture?

This is what I was saying about using the fuel tank itself and it's contents as a heat sink.

I understand that the EFI systems use this but I don't just go and presume that all is well and good.

What happens when the tank is nearly empty and you are spraying hot fuel back into the tank? The Pantera tank is in VERY CLOSE PROXIMITY to the exhausts?

I guess I would question where the additional heat is coming from? The engine? If the regulator is away from the engine would it make much difference?

It could give you the opportunity to run a fuel cooler to reverse the process?

In the case of the "Webers" when the engine is shut off, the heat rises out of the engine, through the runners in the manifold, then up through the carbs.

Draw a schematic. You will see that you have just drawn a heat sink.

How hot does that fuel get? Don't know. It does effect the fuel pressure reading in that it goes from 3-4 while running to about 4-1/2 psi right after the engine shuts down.

I do not think that my set up is unique.

If there is an issue it is with the stock Weber inlet valves. They are not consistently good.

This entire subject was a dead one as far as I was concerned until Tennessee Tim brought it up and decided a return on his kit Cobra was the solution.

In my case, "if it ain't broken, don't fix it", but it is something that caught my interest "as a point of interest".

I don't see a huge difference between a Pantera with a metal fuel tank and having a return added and a current production vehicle with EFI a return and a high impact plastic tank BUT I have never seen this discussed and there is a difference.

Thus is the point of my post.

I will have to look at his post again. My regulator set up was with a return line but the regulator was at the top of the tank so it did not get the heat of the engine.

I would say you have a regulator before the carbs sending 3psi in and a reg or relief valve connect somewhere after the primary reg set at 4 which returns back to the tank.

I would says since your running low pressure and consuming the fuel and very little would be returning to the tank ... ( remember we are not circulating fuel like a closed loop system like the Cooling System) so I;m sure mixed with the rest of the fuel in the tank the temp difference would be minimal ? Instead of metalic lines use braid lines to reduce the heat transfer from the engine to the fuel ?

Do you insulate the tank to prevent heat transfer in or do you use it uninslated to disapate the hot fuel coming back ...

Seems we need to use your car DOUG as a test car ... LOL


Ron

quote:

Originally posted by accobra:
I would say you have a regulator before the carbs sending 3psi in and a reg or relief valve connect somewhere after the primary reg set at 4 which returns back to the tank.

I would says since your running low pressure and consuming the fuel and very little would be returning to the tank ... ( remember we are not circulating fuel like a closed loop system like the Cooling System) so I;m sure mixed with the rest of the fuel in the tank the temp difference would be minimal ? Instead of metalic lines use braid lines to reduce the heat transfer from the engine to the fuel ?

Do you insulate the tank to prevent heat transfer in or do you use it uninslated to disapate the hot fuel coming back ...

Seems we need to use your car DOUG as a test car ... LOL


Ron

My car is a rolling test bed already. So far it is successful. I am still here to talk about it all!

How does Tennessee Tim's system work? The carbs need to be protected from excessive pressure. How can you do that with the pressure regulator on the exit, not the entrance?

The return I think will bleed volume off of the system at full load. I can see benefit to it as a pressure relief to the system with a major restriction to it. Probably some type of an internal pill like on mechanical fuel injection system.

quote:

Originally posted by PanteraDoug:
OK. This discussion brings up two more subjects that I see.
1) on Tennessee Tims plumbing system with the Weber carbs and a return line to the tank, how do you protect the carbs from receiving more than 3-4 psi of fuel if the regulator is behind them and not in front of them?

2)considering that we are returning hot fuel to the tank with the return line, how do you protect the tank itself from being susceptable to a flash explosion? Particularly considering that liquid fuel under pressure is going to have a tendency of atomizing, i.e., mixing with the air into a combustible mixture?

This is what I was saying about using the fuel tank itself and it's contents as a heat sink.

I understand that the EFI systems use this but I don't just go and presume that all is well and good.

What happens when the tank is nearly empty and you are spraying hot fuel back into the tank? The Pantera tank is in VERY CLOSE PROXIMITY to the exhausts?

I don't know if this is of any help at all but on my fuel injected setup a large amount of fuel (enough for maximum speed and maximum load) is always being fed to the injector rails all the time.

Most of it (99%) when at idle and driving slow like city driving will be returning to the tank.

This returning fuel is hot. it has just traveled through all the pipework, pumps and filters in the engine bay and it picks up a lot of heat.

If you feel the fuel tank after a drive you can feel it is quite warm. The tank is being used as a heat sink to remove that heat from the fuel.

Is this dangerous ?

Hot returning fuel would vaporise in the tank producing vast amounts of gasoline vapors, there would in fact be so much fuel vapor the "air" in the tank would consist mostly of that and there would be almost no oxygen. The "air" in the tank is so rich it will not burn.

Fuel vaporising in the tank both makes the atmosphere in the tank extremely rich and also pushes any air that was in the tank back out the breather to atmosphere.

I use one of the fuel tank caps that has pressure relief valves in it rather than just a straight breather hole. It allows air in only if the pressure inside the tank falls to a certain point.

I find it does not let air in while the car is running. That is because the vaporising fuel is actually pressurizing the tank and it does not require outside air to replace the volume of the fuel being used. the volume of fuel being used is being replaced by fuel vapor !! If the pressure gets too high (1 psi) it allows vapor to escape to atmosphere.

When the car is switched off and is left to cool down the gasoline cools and the vapors condense and the valve in the cap does allow air to enter the tank from atmosphere. This would allow oxygen into the tank but now the car is not running and is cold. When it is started and warms up the fuel once again heats up and the fuel vapors push the air back out and the "air" in the tank becomes super rich with fuel vapors again.

This is just an area that never required thought on the subject by me before.
Obviously with current production vehicles running EFI the return line is an important component of the fuel system.
As you point out, the hardware of the fuel supply system all adds engine heat to the returned fuel.
Whether or not it is an intended feature of the sysetem, in effect it works as a heat sink and the fuel in the tank is the major component of the heat absorbsion consideration for the system.
As you point out, then tank venting becomes a significant component as well.
I've already come to these conclusions.
Now the thought is, "if it ain't broken, don't fix it" theory, do I need a return line? What benefit does it offer? What issues will it create?
That's the point that I am at now.
I'm thinking that unless I get the tank ventilation correct now, will I be creating unexpected vapor lock for one thing?
Where do I get a pressure re leaf valve/regulator for the the return that is somewhere around 4 psi? Most are going to be around 30 psi for existing manufactured vehicles.
What do I do with the tank ventilation valve in the tank? What do I do with the filler cap?
All worthy of consideration for just a simple thought of adding a return line?
Thanks for all of your inputs.

I think along PD's concerns the heat of the fuel in the tank is a concern 2 fold. First cooler fuel is better for running the engine and it helps to keep it more consistent for tuning purposes.

But second, the Pantera fuel tank is next to the engine already making it hotter then stock tanks on other cars by default. Adding heat creates a lot of fuel expansion, gassing and other dangerous issues.

Combustibility inside a tank isn't the issue. You can't ignite anything inside the tank; case in point the millions of cars which run fuel pumps inside a fuel tank which when removed spark like a night sparkler.

However expanding gasses throwing the fuel vapor into an oxygen rich environment around the engine and headers is a real concern.

I do think however if cooling the fuel system is a real need then a cooler on the return line could actually help.

If you don't mind using a electric fuel pump, Carter make a vane pump with a internal pressure relief valve that does not require a return line to the tank.

Pressure is set at 4 psi. The part number is P4070.

It also has the advantage of not supplying the fuel in pulses like the mechanical diaphragm does.

I have used this pump before with carbs and as a booster pump on efi systems and found it to be very reliable.

I'm using two pumps. A Holley mechanical and a Holley electric.

The Pantera-Electronics Ignition controller ramps the electric pump to vary the pressure as required by the engine.

As a result the pump is not on all of the time.

The pump has a built in pressure relief valve also. This is the low pressure (red) pump set at a 4 psi limit.

The pressure gauge is plumed 1/2 way into the system.

I haven't had any problems with pressure, fuel delivery or any issues as is.

I'm just investigating the pros and cons of adding the return line to the tank since it is so easy to do in this car.

I don't have any plumbing of the tank vent check valve and presuurizing of the tank via a return line to the tank may be creating an issue of fuel fumes in the engine compartment from it and in a Pantera could be a very bad idea.

My fuel filler is the outside neck type not the early filler inside of the engine compartment.

I was just looking for feedback on what Tennessee Tims fuel plumbing design does.

His remarks and his claim that he needed it to keep the carbs from boiling over indicate other issues with his installation that he has not dealt with correctly from what I know about these systems and I have never seen anything like it or the need for the return line in the thirty years that I have been dealing with Weber carbs.

Looks like he is the only one to have done this?

One additional thought on the rise in fuel pressure after shutting down the engine hot, is that the floats in the IDAs are the old style brass ones.

As of yet, I have not had a Weber float colapse, but I have had that on Holley carbs. They Holley carbs should be converted to the sold nitro fill floats to eliminate that possibility.

That would be a good idea on the Webers too but those floats so far have been elusive at best. It is something that I need to do to have confidence in driving the car on 1500 mile jaunts. Webers definitely make you paranoid about absolutely everything. Worrying about what you might have missed is always there, but then I have had SO MANY issues with Holleys I worry about them also.

I suppose the end result is the return line is a trivial detail, but one that could come back and bite you...and lethally too?

quote:

I was just looking for feedback on what Tennessee Tims fuel plumbing design does.



but then I have had SO MANY issues with Holleys I worry about them also.

Tennessee Tims fuel system set up is essentially the same set up as for fuel injectors.

In injection you have a pump feeding two fuel rails, then these rails are connected to a regulator (or pressure relief valve) that once a preset pressure (say 50 psi) is reached in the rails allows the extra fuel to escape back to the tank thus maintaining the preset pressure very accurately in the rails and to the injectors.

Tennessee Tim has a pump feeding a fuel line that delivers fuel to each carb (like injector rails deliver fuel to injectors) and then at the end of that line he has the regulator (or pressure relief valve) that allows the pressure in that line to only reach 2.5 psi and then allows the extra fuel to flow back to the tank.

This type of setup can cope with a much larger quantity of fuel being delivered from the pump and still maintain the pressure setting very accurately.

So if you have a very large pump to supply huge amounts of fuel to a engine that requires huge amounts at WOT (maximum speed, maximumum load) then that very large amount of fuel can be hard to regulate accurately when engine demand for fuel is low, like idle or cruising.

But if your pump is variable volume, such as controlled electronically to vary it's speed with actual fuel demands, then the pressure relief valve system with the return line back to tank is less necessary and the more simple system of a pressure regulator with no return line can work ok.

There is a trap here for the unwary.
In the Fuel injection system and Tennessee Tim's system the "regulator" is in fact misnamed, it is actually a pressure relief valve because it maintains the system pressure by allowing excess fuel to escape the fuel system and return unimpeded to the tank. This works like the pressure relief valve in a hydraulic system.

A regulator works a completely different way.
It creates a restriction to flow from the pump to drop the pressure on the outlet side of the regulator to the preset level. Like the regulator on a gas cylinder.

This basically deadheads the pump so the pump needs it's own mechanism to prevent over pressure, ie it's own internal pressure relief valve. Such as in Holley or Carter electric pumps.

Pressure relief valves work best with liquids and regulators work best with gases.

What tends to happen when you use a regulator with liquids is at high flow rates the liquid will flash off into vapor as it passes through the restriction that produces the pressure drop. Like the expansion valve in a refrigeration system. Minute bubbles of vaporized fuel in the fuel going to the carburettors may not be very desirable. The pressure relief valve set up does not produce that problem.


Holley carbs ?? I have had SO MANY issues with them too. That's why i went to EFI.