27-01-2022, 12:12 PM
Hi Tom
I think that for LCES the car must be unmodified. A pre 1931 Chummy would have an updraft Zenith. So I think that for an easy swap between carbs you would need to either turn the manifold upside down and have a down draft SU or as you surmise a custom made manifold.
Alternatively you could always “doctor” the Zenith. I believe Robert Forman described this somewhere on the forum. I’ve got a “doctored” carb following his description ready to fit on my RK. It involves a wider Venturi, thinner butterfly, jet alterations and a bored out manifold. I’m not sure if this mod would be allowed under LCES rules but it would be hard to detect
.
Cheers
Howard
I think that for LCES the car must be unmodified. A pre 1931 Chummy would have an updraft Zenith. So I think that for an easy swap between carbs you would need to either turn the manifold upside down and have a down draft SU or as you surmise a custom made manifold.
Alternatively you could always “doctor” the Zenith. I believe Robert Forman described this somewhere on the forum. I’ve got a “doctored” carb following his description ready to fit on my RK. It involves a wider Venturi, thinner butterfly, jet alterations and a bored out manifold. I’m not sure if this mod would be allowed under LCES rules but it would be hard to detect
.Cheers
Howard