If you were to run a single sidedraft weber what would be the best size carb and what choke sizes for a worked a14?

Im currently running twin Su's and just wondering how a single 40mm weber would go in their place. Im not looking for extra performance. The same performance with less fidling around. The Su's are abit old now and need a real going over. I have tried a few things yet their still running rich mainly at idle. Even Ian Stewart has no real idea unless I give it too him for the day. Possibly more dollars than worth.

Cheers

Freak, sorry to divert the thread at this early stage, but what size SU's are you running? I have an old pair on a L series manifold and I'm trying to work out if its worth doing them up and finding/ making a manifold.... Im running a mild A15.

Cant say that I actually know, but thinking about it logically, your throat size should be the same regardless of single or twin sidedraught webbers. Unless you have a wild cam, won't each of the two throats only ever be filling one cylinder at a time?

i.e there is very little time when cylinder 2 inlet is open at the end of the inlet stroke and cylinder one inlet is open at the start of the inlet stroke (for the next cycle)

Therefore you shouldnt need a bigger carby

Yeah im running 1 1/2 Hitachi Su's (38mm) They honestly work great. Provide really great driveabilty with very responsive throttle. No flat spots at all and do provide good performance. Much smoother and pulls alot harder in the above 6000rpm range. I just have some teething problems that are starting to get to me. As the revs increase it seems to run the correct mixture. I still get good mpg. 260miles out of close to 36L. Just the damn idle. It runs friggin rich.

Heres a question for those in the know. It continues to run even with the mixture screws wound right up. I put a basic kit through them, shafts feel good, and floats are set correct and i have even chaged to much leaner needles. Possibly jets?

Yeah I see what you mean about the carbs vs airflow now. Might give it ago yet.

Cheers

i ran a 45dcoe on a stock a12,but this is over 20 years ago,so i honestly can't remember.i don't think i even changed chokes from what it cam with.if you can find any mini racers,try to pick their brains,as my carb came straight off a mini.so,a 1275 or a 1310 mini motor should be close.maybe a browse of 'how to modify your a series' by david vizard would help.maybe the local library would have a copy so you don't
have to buy the book.or maybe someone else on the site has this book & can have a look for you.

su's suck dcoe all the way 40mm or 42 mm weber dcoe or dellorto is the go but they are quite thirsty if tuned for performance can be good on fuel if tuned for economy

What do you think about a 40dcoe jetted and choked correctly on a worked A14/A15 reving to around 7000-7200. Basically im after a comparison between the Su's and a single 40dcoe. Id be happy with even performance I just dont want to go backwards.

if it was me i would go a little bigger say 45mm and jet and choke down because the fuel bowl is bigger and at sustaind high rpm is less likley to run out of fuel but i think a 40-42 would be ok the trouble is finding an absolute guru on webers they are getting rather scarce luckly i know a couple