Triple 45 weber static base settings need help

Can anyone help assist in the base settings since I just fit triple Weber’s to a 4.2.
I got it running although rough and prefer to start with resetting screws rather than attempt anymore by ear.
Thanks in advance,

There are some helpful Weber setting videos on You Tube which I have used successfully.

I have two Weber DCOE 42 on my Cosworth Vega and know the idle mixture can be adjusted with mixture screws but I thought off-idle had to be done by installing proper jets and such to match the engine. My Weber set up came as a kit from specialist with the Cosworth Vega engine so I have been very careful to not mess around with any changes to mine except for idle mixture and occasional seal replacement, cleaning and synchronization with a Unisyn tool. Mine have been very reliable for 30+ years but have heard that getting them dialed in initially can be tricky since I think you must have a good selection of jets and such to do the job. My 2 cents and I have no experience with them on an XK.

68 E-type FHC

It is very difficult to determine a “base setting,” given the vast number of settings.

Generally, on a stock engine ( assumption), I’d say:
-chokes = 30 mm
-emulsion tubes = F11
-main jets = 110
-air corrector jets = 200

The rest will need to be done on a chassis dyno, and/or hours of on-road testing, and a pile of expensive parts.

Ok thanks 4 advice wigs. All I got is an ear, a synchrometer, and a screwdriver. No hours of on road testing or expensive parts.

It would be good to list the parts you do have, and to make friends with someone who has lotsa Weber parts.

What kind of weber parts?

What does the carbs have in them, per my list?

Agree. Many years ago when I had triple 45 DCOE on my E Type, they needed to be setup on the dyno. Once they were done this way, the car was an absolute rocket.

45s are more tunable than 40s, which is why I preferred them.

Do you recommend 30mm chokes b/c you live in Colorado, high elevation?
Would you say the same at sea level?
Michael Caro

Hasnt got a lot to do w/altitude: has to do with driveability/throttle response on the street.

Remember, on an E, a 2" SU feeds two cylinders, plenty.

I got them running fairly well at the moment. Luckily I befriended a local to me who has an e type race car who will be coming over to help me tune the car properly. This was first start last week

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When r u going to fly out to give me a hand Wigs?

Not setting foot in an airport, or on a plane till herd immunity is reached.

Look for me in 2022.

Sounds all right but you need to see how they go on the road and they will also shift a bit as the heat gets up to normal and then again when above normal!
In a non stock engine at more or less sea level… For an engine with stock cans an exhaust then 36mm chokes possibly better.

Main Jets 160
Air Corrector 190
Idle Jet 65F9
Emulsion Tube F16
Main Venturi 38 mm
Aux Venturi 3.5 mm
Pump Jet 0.45
Pump Exhaust jet 0.40
Needle valve 2.00 mm

If they are 152 Webers then the recommended idle mixture screw off the base is 2 (2.25) to 3 turns out. More or less than that then change the idle jet. I use Colortunes to to see what is going on in the absence of O2 sensor which is still averaging depending on where the sensor is.


One other point on the 152’s is do you have 3 or 4 progression holes?.
The idle circuit supplies fuel until the main circuit kicks in which is usually in the 2500 to 3000 rpm range. If only three progression holes then it will run rich at “idle” to avoid the dreaded Weber hesitation on acceleration.

Hello Keith,
30 years ago I bought Weber’s for my 1969 FHC, stock engine B/C I thought more of anything anywhere is better. I have since learned. Since then the car has been totally rebuilt (took 25 years due to life).
The engine totally redone years ago, but first start on 12/11. Bored +.030, Iskendarien XM2 cams, Weber’s are 45 DCOE 152, & JT-5 tranny. What is the difference W/O 152 # ? I have a friend (previously owned the car) who 1/4 mi. races , won nationals in his class 3 years ago & helps me (really I help him) W/my car. Hey’ll say “too rich, too lean, top end, bottom end” etc. Here are my current settings:
Main. 155
Air correct: 200
Idle: 60 F9
Needle valve body: 250
Needle valve: ? Didn’t want to pull floats b/c friend set them.
Accel pump jet: 40
Accel. pump exhaust valve: 45 (can’t read #s) I say this b/c I have a bagW/ 40
From the days of everything bigger if better).
Chokes: 38
Aux. Venturi not sure. Can take out if necessary but last time I changed chokes
to 36 to experiment I reversed 2 aux Venturi; yikes figuring that out!
Emulsion tubes F2. There are 4 diagonal holes top of collar above above main.
8 holes above rim on top of collar.
2 holes above the 8. And 2 more above that.

I also have a set of F16 w/ 4 diagonal holes top of collar above main.
8 holes above rim on top of collar. Nothing above them.

The car runs really good & pulls very hard. But from your mains & air correct it’s possible they might provide more top end pull? I have both in my tool box.
I live at sea level. Thanks, still experimenting.
Michael Caro

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I started where you are now, a pig in poke,screwdriver, no dyno, no parts.
3 great books: The Weber DCOE manual- really a booklet.
Weber Carburettors Tuning & maintenance, John Passini.
How to power tune Jaguar, Des Hammill.
Sometimes I think these carbs are like getting a college degree on their own.
Start W/what wiggles wrote esp, chokes on a stock engine. Then read,
read, read. 2 of these books have SO Much info. Some unnecessary. But a little reading & the pros on Forum (I’m-not one of them)once you learn what questions to ask will put you far ahead.
Weber parts to buy &play around.
Michael Caro

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Thank you Michael, I will surely be reading and may even order those books you mentioned. Looking forward to making headway.