Carb trouble

[damien]

Hi all,

I have recently restart my 2.0 67 coupe after massive engine maintenance.

New mechanical advance, float height at 48,5mm (40 DCN).

Engine works great but at stabilised rpm, around 3000/3500rpm (on the road), there is an hesitation, instability. No problem when I press gas pedal.
Only at stabilised rpm, cruising on flat road.

Thanks.

[Dinoswede]

This "classic" hesitation is probably just depending on too small idle jets. To work well with our "modern"
ethanolmixed fuel, the original 0.50 or 0.55 are too small.
Try 0.60 or even 0.65 instead. That, and strong ignition sparks from a working Dinoplex or MSD ignition
usually makes a big difference!


Dinoswede

[Ribolla_67]

Hello Damien,
modern fuels have approximately 7-10% less caloric value than Super gasoline from 1970.
As Dinoswede said, try one number larger idle jets - and then increase the main jets slightly.
I must check my current values during the weekend…

[Stefan2000]

In this video is a reply with my jets settings on the 40DCN's
It was finetuned to get rid of the lean spot and also for peak power.
https://www.youtube.com/watch?v=SC0bA_vHZZM

[ThomasK]

I Drive since years on my 2,4 Coupé with 0.55 Idle jets and a little richer idle adjustment without any hesitation issues…if float level is right check fuel pressure…

[damien]

Hi all,

Thanks a lot.

I ordered 60 idle jet and a fuel pressure tester.

Do you have an "how to" ajust idle mixture screw?
I'm not very good at this game.
Throttle valve synch is ok.

Thanks.

[Fanalone]

Hi, youtube is sometimes a good source, take a look at this video from Weberology:
https://youtu.be/dBs7GzSLLCc?si=MURYX261oIPjj2Em

BR
Erik

[Ribolla_67]

Hi Damien,

The best instruction is from Roberto Calisi - you can find it in his blog:

http://dino246blog.blogspot.com/2014/08 ... s-and.html

[damien]

Thank you all.
Work in progress

[Gaelicguy]

Thanks to all responders, there is a lot of good information that you will not find anywhere else without the willingness of our members to share our value of keeping our nearly 60 yr old cars on the road.
Thank you
Michael