When I bought the car it has a hif44 but the acceleration was abit delayed. The dellorto I have is great but I want to go for a mk1 single speedo and I cannot do that with the caeb box. Now that doin a full rebuild and changing cam from a kent 544 to a kent 266 cam I was thinking of maybe going for a twin hs4 set up. But I have never have never experienced what they are like. I'm trying to aim for more torque if possible.
For the street, I feel to get anything better than an SU, you need to go to Injection. If you felt that the SU was 'lethargic' than that would only have been from an incorrect set up, which a Delorto or Weber can equally suffer from, but more often than not, with those compound carbs, the symptoms are more masked due to the 'course' way in which they work at lower air flow rates.
Why I am drawn to an SU for the street is that type of driving needs the widest range of outputs from an engine than any other, with much more time spent at the lower end of the rev range than the upper end. In competition, it's a different kettle of fish where it's almost 'on or off' type of driving and with the way these engine deliver their power, always at the upper end of the rev range.
The wide range of needs for street driving does mean that air flow rates are also wide but mostly at the lower end of the scale and that's where and SU stands head and shoulder above any other Carb out there. These Carbs have good atomisation at just about any air flow rate and even when an over sized SU is fitted, they still drive just fine with little poor effects from this.
A real down side of Delortos and Webers is at these typical street driving speeds, the air flow rate through them is quite low and they have very poor, if any, fuel atomisation at these rates, so they are always going to be running richer than an SU at this lower end. I can always tell when lifting the head off an engine when it's been running a Delorto or Weber that the 2 centre cylinders are clean and lean and the 2 outer cylinders are black and rich. That comes from the weight of the fuel mix and it's distribution that's further compounded by the necessary shape of the manifolds needed when these carbs are fitted. It's also why engine life is much shorter with these carbs too, with the outer cylinders suffering from bore wash.
Compare this to a Single SU, which looks to have a 'worse' manifold, yet fuel distribution between all cylinders is very even, so when tuned, there's not compromise, which is impossible to get away from with a Delorto or Weber.
