[M30B35] Triple weber 45 DCOE installation

jc971 said:
so if I understand the carbs in 40 with 34 chokes for my engine to have the maximum torque
and maybe 36 chokes to get the horses higher rpm
Click to expand...

I don't think it's quite that simple, but I'm no authority.

the m30b35 making its maximum power at 5700 rpm
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OK, well the numbers I ran in post #17 used a lower RPM figure, so perhaps 36's would be better if you plan to regularly run at 5,700 RPM. But for normal street use, I suspect you'd get a better idle, and plenty of torque & HP with 34's. For a race engine, with a cam that won't let it idle anyways, larger chokes might be preferable.
 
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jc971 said:
Hi guys
thank you for the informations
so if I understand the carbs in 40 with 34 chokes for my engine to have the maximum torque
and maybe 36 chokes to get the horses higher rpm
the m30b35 making its maximum power at 5700 rpm
i will try to install an afr gauge for the set of the jetting
but i will start with the formula for it
Click to expand...

Be careful a out going too big.

With larger verturis you are not reducing max torque, but are instead moving the torque curve upward relative to rpm. At any given rpm under 2500 rpm, the engine will not pull as hard, which will make the car feel slower. The engine will not pull as hard from a standing start, you will want to run it up higher in the rev range before shifting into second, and you will be downshifting sooner at higher rpm.

And you probably will need to get above 4500 rpm before you feel your hp gains. Most street cars don't spend a lot of time running above 4500 rpm.
 
Remember that changing chokes will affect the rest of your jetting which means time, frustration, cursing, and more $$$. Get a set of jet drill bits from Pierce Manifold, download the Weber Tuning Manual and read it, and start with smallest recommended jet and air bleed sizes. Then you can drill out until you like your AFR. I’d say start with 34 and commit your jetting to that, like mentioned above, you won’t spend a lot of time at the redline so jet for torque it is much more sensitive to jetting that the high rpm horsepower number. You’ll notice the lack of acceleration from too big a choke before a few extra hp.
 
Ok i understand

after what i read on dave home page
what I could note for my engine: 3.5 220cv 5700rpm
caburator: 40
venturi: 34
main jet: 136/138
air corrector: 190
emulsion tube: F2
idle jet: 45f9 or 55f8
 
and what do you think about this configuration :
carburetor :40
venturi : 35
main jet : 140
air corrector : 190
emulsion tube : F2
idle jet : 45/55 F8 or F9

I know I would not have much opportunity to use my engine in high rpm but I'm afraid it lacks power at high rpm
I think the B35 already has power at low rpm
 
jc971 said:
and what do you think about this configuration :
Click to expand...

I think you should try it and see how it feels. Use an oxygen sensor to measure how it delivers fuel under a variety of conditions. Make adjustments accordingly.

It's pretty tough to just look at a list of specifications and advise you how it will perform - Weber jetting depends on your altitude, the octane of gas you use, your engine's cams, compression ratio, model of 40 DCOE that you're using, phase of the moon, your height & weight, etc. etc. etc.
 
The 35 will affect your torque and progression more than it will noticeably affect your horsepower. If you want a place to start, start small and drill up:

carburetor :40
venturi : 34
main jet : 130
air corrector : 180
emulsion tube : not sure yet, where did you get F2?
idle jet : 50 F9 (F9 is richer than F8 so can be drilled leaner)

I suspect this will be overall a little lean but can always go richer on fuel bores and leaner on air bleeds with a drill. In order to take advantage of larger chokes you'll really need a hotter cam and some headers.
 
I have a camshaft of code 3 which means that it is a 272 degree in my stock
I hesitate to make the change in my b35 cylinder head this will allow me to mount my original ignition system without modifications, and maybe a power gain ?

I quote a conversation I found on this forum

Identifying Stamp

I believe the camshafts all have the same part number, but the grind is identified by a number stamped on the back end or the camshaft. This is edited from a previous discussion:

Remove the Cover on the backside of the head and look at the number that is stamped on the cam.

1 = 260° (2500) lift 6.8471mm (8.9mm at valve)

2 = 264° (early 2800) lift 7.4228mm (9.7mm at valve)

3 = 272° (late 2800 and all 3.0) lift 7.4228mm (9.7mm at valve)

For comparison, the milder Schrick grind has 282º duration and lift of 8.4/10.9mm. There are differences in the lift figures quoted on the various websites, but these are based on a 1.3 rocker arm ratio.
 
i don't think changing the cam will do anything to the ignition system unless you get the cam for an old school distributor ... which would change things. i would think that a schrick would make the webers come alive
 
Good morning
I bump this topic
I mounted my weber with the following configuration:

carburetor :40
venturi : 35
main jet : 140
air corrector : 190
emulsion tube : ?

but I did not change the emulsion tubes, they are the ones that were delivered with the carbs
I don't know which emulsion tubes to choose
I find that this configuration chokes the engine a little it pushes well up to 5000rpm then it makes a lot of noise for nothing
 
jc971 said:
Good morning
I bump this topic
I mounted my weber with the following configuration:

carburetor :40
venturi : 35
main jet : 140
air corrector : 190
emulsion tube : ?

but I did not change the emulsion tubes, they are the ones that were delivered with the carbs
I don't know which emulsion tubes to choose
I find that this configuration chokes the engine a little it pushes well up to 5000rpm then it makes a lot of noise for nothing
Click to expand...
Pull an emulsion tube and see what it says, if no writing post 2 pics of the sides rotated 90 degrees apart. Do you have an AFR gauge installed?
 
When you say makes a lot of noise for nothing, do you mean the car doesn't continue to pull, or does power actually drop off?
 
I might humbly suggest that if you want the best, most trouble-free, great looking side draft linkage system, you might look at our system designed specifically for the E9/E3s:

www.2002sonly.com

Weber Triple Side Draft M30 | 2002s Only

The M30 Triple Side Draft System is based on the same rock-solid, low maintenance components as the M10 system. It includes everything from the bell crank to the triple Weber throttle shafts. It is $285 plus shipping. Please select either Weber DCOEs or Dellorto DHLAs. NOTE: DOWNLOAD THE...
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I had thought that changing emulsion tubes is very complex and that you need a dyno to make a proper comparison.

Consider that air correctors have a more pronounced effect higher in the rev range, and that is where you are having problems. I would move to smaller correcters as the next step here.
 
JC971,
It could be too rich, too lean.
I had a stock 3.3 liter m30, which pulled very strongly up to 6400rpm with 34mm aux venturis, so I think your 35mm is not likely the problem.

I would start by changing the air corrector (1 step smaller or larger), and then try the main jet. In my experience, most drivability issues can be fixed without changing the emulsion tube.

A $200 wide band air fuel meter is very helpful when diagnosing carb setup problems. If you can’t afford one, ask around to seek of a local friend has one they can loan you. I use this one and have a tail pipe adapter for cars that do not have an O2 sensor bung in the exhaust system. Innovate

When I got my current E9, it would not accelerate beyond 4200 rpm. A wide band AFM showed the problem in one short drive (much too rich). I changed a few parts (idle/main jet and air corrector), but not the emulsion tube. Now the same engine pulls to 6000 in a smooth linear fashion.

John
 
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I do not have an afr gauge but I will consider installing one I understand its usefulness
i read f11 on the emulsion tube
I have to try smaller or larger air jets depending on if it runs too rich or too lean
i have a 123ingition lighter
it's a great feeling to hear the engine rev up with the webers but it's even better when it pushes hard up to 6000 that's what I want for my car
8B6D24F7-2E66-45E0-82A5-6C9E8A471176.jpeg
818AA598-92A0-4175-85FC-35F61F0D5043.jpeg
 
A full setoff jet drills used to be available from Weber. When I had my Etype with 45's on it, iI had a rough time dialing them in. So I would drive down the freeway, stop every now and then to pull a plug and see what was going on and got the jet drills out.. I never got them lean enough and went back to the SU's which were modified. However it still went "quickly" So, yes get a set of jet drills they shouldn't be expensive
 
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