Which Carb set up Twin HS2SU or twin HS4

[Holiday97]

Hi everybody, Searching for ideas, I have a 1300 dolly featured in this months mag. My engine has had a lot of work, Head planned 50thou, fully ported and polished, larger inlet valves, new valve seats and bronze guides, stronger valve springs 4 branch exhaust manifold , stage one cam, electronic ignition. at the moment I have a rebuilt set of HS2 SU's, AAQ needles and red piston springs on a spitfire inlet manifold. I have been reading some reports that twin HS4's might be better as they breath better. Any thoughts.

[cliftyhanger]

A pair of HS2s will be good for 100bhp or more. You may need to change to yellow springs, but a rolling road session is needed.
I have no idea what your "stage 1" cam actually is. So it may be something akin to a mk3 spitfire cam, the rest of the engine sounds as if it similar.
Have you modified the distributor to match the engine spec? Again a good rolling road should be able to swap advance springs around to optimise things, the distributor doctor can also advise, especially on the vac advance.

[cleverusername]

Find yourself someone with a rolling road and have it tested with both carb setups. I say this because it is very easy to lose power when tuning engines, instead of gaining. There was an article years ago, compared tuned cars, I think they were TR6s. They found the most powerful car was the one with the standard factory setup.

Unless you know how much power is reaching the back wheels, it is very difficult to tell whether your work is many any difference.