I thought it was a good idea to question the collective wisdom of the bb in order to understand if what I observe is a inevitable/expected issue or if there is a fix that has been already found by others.
I checked in many bb threads but I didn’t find a straight answer.
I run a modified ‘fast road’ 1.8 litres carburetted twin spark on my GT Junior step front.
The carbs are the 45 DCOE 152 ‘Spanish’ Webers with the 36 standard venturis. They are brand new and carefully balanced.
I checked all the car’s settings, advance, cams timing etc and the engine pulls strong with no high end problem whatsoever.
I have installed a AEM UEGO meter to keep things in check.
With several years of practice and long readings of the expert’s texts I learned how to get rid of the infamous stomping just off the idle, the flat spot at 2000 rpms that we usually have with the modified/high lift/longer duration cams.
In my case this involved the drilling of the forth progression hole, and the use of somehow rich idle jets, like 60F9 for example, and a lot of road testing.
Now the issue is that if I set the car for strong acceleration with no ‘flat spots off the idle’ I get over rich mixture at cruising, for example at 120 km/hour.
This is around 4000 rpm with the gas JUST opened. The car runs at 10 ratio and it shows the typical hesitations we see at over rich steady driving.
If I fix the issue, for example by going to 55F8, I have a nice driving experience, no over rich mid range cruising and by the way, better mileage. But the flat spot in acceleration just off the idle is back.
I understand Webers are not designed to distinguish between a status where the butterfly valve is just opened because the light became green in town or because you are calmly driving on the highway.
Nevertheless I wonder if someone has found a fix to this issue that could be circulated here.
I checked in many bb threads but I didn’t find a straight answer.
I run a modified ‘fast road’ 1.8 litres carburetted twin spark on my GT Junior step front.
The carbs are the 45 DCOE 152 ‘Spanish’ Webers with the 36 standard venturis. They are brand new and carefully balanced.
I checked all the car’s settings, advance, cams timing etc and the engine pulls strong with no high end problem whatsoever.
I have installed a AEM UEGO meter to keep things in check.
With several years of practice and long readings of the expert’s texts I learned how to get rid of the infamous stomping just off the idle, the flat spot at 2000 rpms that we usually have with the modified/high lift/longer duration cams.
In my case this involved the drilling of the forth progression hole, and the use of somehow rich idle jets, like 60F9 for example, and a lot of road testing.
Now the issue is that if I set the car for strong acceleration with no ‘flat spots off the idle’ I get over rich mixture at cruising, for example at 120 km/hour.
This is around 4000 rpm with the gas JUST opened. The car runs at 10 ratio and it shows the typical hesitations we see at over rich steady driving.
If I fix the issue, for example by going to 55F8, I have a nice driving experience, no over rich mid range cruising and by the way, better mileage. But the flat spot in acceleration just off the idle is back.
I understand Webers are not designed to distinguish between a status where the butterfly valve is just opened because the light became green in town or because you are calmly driving on the highway.
Nevertheless I wonder if someone has found a fix to this issue that could be circulated here.