Webers for the e type

Good evening Jag lovers, does anyone knows of a good Weber jetting for the e-type. I have a Weber set-up that needs the proper setting. this is the setting on my set-up :

Main Jets: 145

Idle Jets 65 F9

Fuel Pump Jets: 40

Air Correction Jets : 190

*This is on my Triple Weber 45 DCOE set up. thanks…

What size chokes? What size secondary venturis?

Which emulsion tubes?

  1. Don’t try to use triple Webers on an E type. It will cost you your soul.

  2. Just. DON’T. Triple SUS are better and tunable.

  3. Take your Weber setup and burn it. Then douse the flames with holy water.

  4. Randomly pasting stuff from my archive.


Weber carb setup recommended in the Haynes carb manual for s1.5 E Type:

Choke = 38

Venturi = 3.5

Emulsion Tube= F2

Main Jet = 1.65

Air Corrector Jet =1.90

Idle Jet = 0.65 F8

Accelerator PumpJet = 0.40

Accelerator Pump Inlet Valve with Exhaust Orifice = 0.50

Needle Valve =2.00

  1. Garth. Just. Don’t.

Be aware that fuel density is very different country to country, a set up that is a baseline start in the US will be a long way out in Australia and vice versa.
Find an expert with all the parts and a dyno and pay them.


Um… if the altitude density is X, at Y meters, it’s not gonna matter what country the Webers run in…:grimacing:

Our atmosphere ain’t that much different!

That said, ay my elevation–1600 m–I found that F2 emulsion tubes didn’t work as well as F11s, certainly for a street setup.

I am not sure of Garth’s elevation.

Couldn’t agree more.

I’m talking about the density of the petrol itself.It varies greatly country to country.


Sorry I missed the fuel part, but I’m not entirely sure it’s going to make that big a difference, wrt to pump gas. It certainly is a small factor when it comes to setting up the carburettors.

Do you have data, showing this alleged disparity? Wrt to the density differences between 100LL avgas and pump fuel, yes, there’s a marked difference, but in pump gas?

only my personal experience with an ex team principle of a factory Honda super bike team who tuned one of my bikes.
He correctly predicted how far out main jets from a US based bike would be when when it arrived in Australia, can’t remember the exact figures but it was huge. His take on it is that international advice is useless. People can feel free to do their own research, believe what they want and set up their carbs how they want, I know what I do works…hand over my keys and comeback with my wallet.

Heh… I may be looking at that scenario, if/when anything major goes Tango Uniform on my Maverick!

For sure, the density of my wallet will be much less.


I can see how disgusted anyone can become when the challenges of making these carburetors performing correctly as seen on track or a smiling owner showing them off at a car show. The reason I purchased these were because the previous owner could not make them work and consequently his car sat for over fifteen years.

I have other cars that I’ve installed Webers that were challenging but I enjoy a good challenge especially if it’s known to work for others. The Maserati Lamborghini Aston Martin’s and Ferrari all used these carbs as standard feature.

The Jaguar V12 uses the IDA Webers three sets on each bank and I’ve not heard anyone upset enough to rip them off or use a hammer to to relieve themselves from the anguish caused. I love the looks of the carbs and I’m thinking of installing them on my coupe or my MK2,

Abowie had me cracking up “burn and dousing the flames with holy water” :joy: :joy: :joy: :joy: that’s funny! I have however learned a few things about fuel density and I’ve been aware of elevation but I did not think it mattered where I am in New Jersey 1200 ft above sea level and not the mile high state like Colorado? If the carbs become too challenging I will seek more professional help or shelve them for a later date pr wall art. Have a great day :pray: PS Thanks Wiggles and others for your thoughts…


I wonder how many people here HAD Webers, the traded them for SUs. I know it’s quite a few. Always the same problems - they never run right, and gas mileage is terrible. SUs work just as well, provide the same real-world power, and MUCH better mileage.

More Weber hate. You guys should b ashamed of yourself. Perhaps it’s not the webers and more to do w operator error :smiley_cat::cat2::joy_cat:


I do believe the webers would perform better than the SUs. The limiting factor in our average mechanic lives is one of experience and access to the required equipment and parts.

Webers require a lot of the aforementioned to get them right.

I had a set on my car, loved them but it was an uphill battle to get them set correctly. The problem was operator experience and as said, access to equipment and parts.

IMO, wrong to blame the carbs when the real problem is owner/driver experience.

This sounds a bit like blaming carbs, any carbs, when the problem lies elsewhere in the engine and it’s support systems.

Hi les, what was your biggest challenge with the carbs and do you remember the changes that were made?

Nothing wrong with Webers, but in 50 years I’ve never seen anyone get them running really well without a dyno, a huge collection of jets, etc. and someone who is very experienced in tuning them.

The V12, if not fuel injected, used four 175 Strombergs. It is possible to retrofit the engine with 6 IDAS.

I owned an XJS race car with IDAs. The current owner is still trying to get it tuned and running properly. It’s nearly there but several grand and hours on the dyno later it’s still not perfect.

My ex boss Chris has seen one V12 E type with IDAs catch fire, and here is a picture of a set of IDAs removed from another V12 because the owner got sick of trying to tune them. I’m sure Chris would sell them.

I agree that it is not impossible to tune triple DCOEs for an E Type, but it is a lot harder than SUs and the performance improvements are really only going to be right at the top of the rev range where an E Type engine very rarely goes.

running really well without a dyno, a huge collection of jets, etc. and someone who is very experienced in tuning them.

Precisely my point Ray!

Therein certainly lies much of the angst about Webers: wrt the process of getting them correct, this author suffers none of that.

I am, however, seared by the experience of having set up many of the beasts, and it would be foolhardy of me to make light of the work and time it takes to do it properly.

Can they be set up to perform well? Yes. Can they set up to give virtually the same performance and economy as SUs? As the Japanese famously say… verrry difficult.

Are they wonderful sounding eye candy? No argument whatsoever! Are they worth the extra time and money?

Personal choice.

My only motivation in this recurring, Jag-Lovers soap opera is this: don’t count on a Weber conversion to be easy or a huge improvement in performance.

On a stock engine, they will not deliver large increases in either horsepower or drivability, over SUs, but can easily deliver the opposite, w/o expert installation.

Little operator error here, but simple and informed life experience, and I’d be remiss to not frankly share that experience. No “hatred” here, but simply a pragmatic and realistic background.

As for ‘burning them then dousing them with holy water?’

Water only works to extinguish the flames if alcohol is chosen as fuel…:stuck_out_tongue_closed_eyes:


The challenge the vast number of permutations possible with the mixing and matching of jets/chokes/fuel levels/progression settings and holes/spill jet/pump jets etc etc. and you can do this for each cylinder!

Fuel level is set per pair of course and the pump jet but the rest are, to the best of my recollection, infinitely variable.

When I got mine, already on the car, they didn’t even have the same size auxiliary Venturi on each cylinder. For where the car was, St Louis, it was probably correct??

My biggest annoyance was the idle, just couldn’t get it nice and smooth. Once the car was rolling though it ran great but very rich.

Not sure how much I spent on parts and books but it was a lot. On my car the std solid throttle linkage didn’t operate very well with them either and I got it converted to cable. Much better!

If I had to do it again, and of course with hindsight, I’d find a specialist and ship it off to them to set it up, then never touch it again.

The std carbs in our cars are very forgiving, this is not the case with Webers, but when they are right, they are awesome……YMMV of course.

Bottom line, if you have the time/patience/money, go for it but find someone who has the parts/experience and equipment (read dyno) to set them up.

Might want to try someone in the classic car racing fraternity.

My carbs were 45DCOE. They had two progression holes, got it changed to three, that helped moving off from idle without a stumble.

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That is true, and in my experience, though a complex bit of work, many overthink the scope.

What absolutely is needed is a VERY big set of parts drawers.

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