Mini manifold

Twin 1 1/4s generally do perform better than an HS4 (I seem to recall Vizards results also pointed in that direction). But a single HIF44 is the best bet short of a DCOE or DHLA.

Either way, carbs alone don't make huge improvements on their own with out other mods.

Yes and no.an HS4 has the potential to flow more air than an HS2 (obviously). The only reason twin HS2's usually give a (marginally) better result than a single HS4 is because of the manifolds. A decent twin manifold gives the carb a more direct shot at the port (conversely a bad twin manifold, and there's plenty, will butcher any potential)However a good HS4 manifold gets this right as well and will outperform smaller twins.

On a hot small bore I'd go for an HIF44 on a good long manifold, or a DCOE 40 if the firewall wasn't an issue.

I suspect the OP is not after all out power though, and might just be after some bling/bragging rights. In which case, go for it!

sorry for delayed reply. Ive thought about it, ill probably go with extractors now if i am going to do my twin carbs, ive found a cheap set of extractors that someones willing to let go of, ive already got the bigger exhaust piping in place. the carbs are in pretty good order and the inlet manifold is reasonable too, they came off an old 1275 engine and worked well ive stripped them back and checked it all out.

the main reason why i wanted to switch up was because my single carb was giving me many problems, i swapped it out with another one in better condition but wasnt running so flash still but livable (did plugs, leads, points, timing and coil, made it bit better) so i thought perhaps ill stick the twins on

thanks for all the feedback guys.

If you cant get a single running right, how on earth do you think you can get twins running better!

If you can't get a single SU running, then assuming the spring, needle and jet is correct, it can only really be lubricatiion (dashpot), mixture, or wear and tear.Heck, there is nothing much else to them!

Got the gear/knowhow to balance the twins I hope.If you can't get a single to work I wish you lots of luck with 2nd hand twins.