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> Webber IDF 40s, Help with tuning
Chad911sc
post Sep 11 2025, 09:18 AM
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So I finally finished every aspect of my restoration and I’m on the final step before really being able to break my new 2056 in. I have the idle circuit close enough to where it needs to be with idle jets of 50. My problem is my transition from idle circuit to the main circuit. I had purchased a set of Gene Berg venturis that were a 30 idle circuit and then with wide open throttle they would increase the flow to 34. I thought this would be good with better flow at the top due to the web cam (86a) which is supposed to be more mid and top range power. I have ported 2.0 heads and 96mm pistons and cylinders. It also has the 123 distributor set on setting #3. The timing is set at 5 degrees base timing and 28 degrees total.
The problem is that if I even try to open the throttle more than an inch or so, the AFR gauge slams over to 16 or higher. So I’ve only driven it a few times after adjustments, and it does the same thing everytime.
I took out the fancy dual plain Venturis and put in a set of stock functioning 30 vents and just took it for another spin. It does the same thing with the 30s.
Current set up:
ET F11
Idle 50
Mains 130
AC 180
Vents 30
My float level is set at 10.5 with the gasket.
I’m at sea level in Florida.
As long as I just ride the pedal gently, the AFR stays in the 12-14 range all the way up to 4000 rpm. It idles at 10.5-11.5.
The carbs have been rebuilt and are synced and balanced.
I am ordering a set of AC and mains so I can adjust further as needed.
Should I try to go down on the air correction jet first to fatten it up on the top?
Or maybe something different with the float height to provide more fuel in the bowl?
Thanks in advance for all your advice. Can’t wait to be able to run this thing!!



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Chad911sc
post Sep 12 2025, 03:44 PM
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Perfect…
Excellent idea. I will change those out in the am and see what results I get. There is so much information out there that contradicts itself. So many ways to tune and get to the desired results. I have read so many posts that lean towards the 28 vents on a 2056. Then the people who make the parts (Webber), say that I should be running a 32 vent with cam and heads. So I settled in the middle at 30 after removing the fancy dual plain ones.
Will report back tomorrow with the feedback.
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porschetub
post Sep 12 2025, 07:53 PM
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QUOTE(Chad911sc @ Sep 13 2025, 09:44 AM) *

Perfect…
Excellent idea. I will change those out in the am and see what results I get. There is so much information out there that contradicts itself. So many ways to tune and get to the desired results. I have read so many posts that lean towards the 28 vents on a 2056. Then the people who make the parts (Webber), say that I should be running a 32 vent with cam and heads. So I settled in the middle at 30 after removing the fancy dual plain ones.
Will report back tomorrow with the feedback.

Hawk said it all about fuel mixture screws they must be set right spec and even before doing carb vacuum balancing ,28 mm vents are the best for Weber /Dellorto ,great transition and good response off idle due to improved vacuum signal and again as he mentioned you can most likely use existing jets .
You could pull your fuel pressure back a bit too 2.5 psi is fine or a bit less.
Good luck ,think you will be closer to the "sweet spot"soon.
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Posts in this topic
Chad911sc   Webber IDF 40s   Sep 11 2025, 09:18 AM
densible1   I'm also at sea level with my 2270 (2256) buil...   Sep 11 2025, 12:01 PM
densible1   Wait, correction I meant 5-7 static advance on the...   Sep 11 2025, 12:04 PM
Chad911sc   After re-reading my post I forgot to add that the ...   Sep 11 2025, 01:13 PM
Superhawk996   How about some homework? Suggest you read this t...   Sep 11 2025, 01:52 PM
Chad911sc   I still have a set of 28 vents, so that is an opti...   Sep 11 2025, 02:16 PM
Chad911sc   So after reading the material you sent me, I thoug...   Sep 11 2025, 05:22 PM
930cabman   So after reading the material you sent me, I thou...   Sep 12 2025, 04:59 AM
Superhawk996   :trophy: :popcorn:   Sep 11 2025, 08:07 PM
Chad911sc   After the test drive today, it is tuned better tha...   Sep 12 2025, 10:55 AM
Superhawk996   I’d normally say increase the idle jet since you...   Sep 12 2025, 02:20 PM
Chad911sc   Perfect… Excellent idea. I will change those out...   Sep 12 2025, 03:44 PM
Superhawk996   Perfect… There is so much information out ther...   Sep 12 2025, 06:52 PM
porschetub   Perfect… Excellent idea. I will change those ou...   Sep 12 2025, 07:53 PM
930cabman   my experience has been, I get them close (no AFR g...   Sep 12 2025, 06:28 PM
Superhawk996   I think it’s probably also worth posting this fr...   Sep 12 2025, 07:16 PM
Superhawk996   And one last item food for thought. The Zenith ...   Sep 12 2025, 07:22 PM
cgnj   I am a Dellorto fan boy. Bought my first set in th...   Sep 12 2025, 07:27 PM
brant   I run big venturis on the race car for 8000 redlin...   Sep 12 2025, 08:24 PM


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