Hi All
I have a 37 Opal, Thinking to fit a 1 inch SU carburetor
Will it make "any" difference to the car ( when i go to santa pod)
Or if its not broke don,t fix it

There has been a huge amount of discussion about SUs; available thru search.
My experience and the general consensus is that an SU makes a notable difference cf 26VA. I found to be as beneficial as a later head. Apart from the later non period semi downdraft models, the horizontal 1 1/8 with dashpot ex some Series E and following sv Minors is probably the most available. Innards same as 1 inch so performance presumably the same on a normal car. All/most 1 inch originally no dashpot, the device a very desirable improvement.

Location: Auckland, NZ

As Bob mentions, there has been much discussion on the Forum about SU carbs. I have used both 1" and 1 1/8" on my 1931 saloon and have found the 1 1/8" to be best. The 1 1/4" is probably too large for a road going car. The beauty of the SU is that it is easily adjustable and bits are interchangeable and readily available. You also have a big needle constantly poking through the jet so you are unlikely to suffer from blocked jets. With my set-up the car will do 40 to 45 mpg driven quite hard up hill and down dale.