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