Hey guys can some ome give me a start point, iv'e got a pair of 40 dellorttos, car has a ported head big valves, cam etc what size jets vent etc to start with thanks

To start with, use the jets that are already in them. Standard jetting will run 1.2 liter to 2.0 liter the same. But because your engine is not stock, you'll want to evaluate the A/F ratio and then adjust the jets to suit.

Big valves & cam? Start with the Dellorto venturis. For a 1.2 liter at 8000 RPM, use 36mm venturis. Every other jet/air sizes follow from the venturi choice.

I've had a look at the carbs they have 31mm venturis,so can I order 36mm and a set of standard 1.2 liter to 2.0 liter jets. thanks

To be honest, if you are going to go as far as 36mm chokes you moght as well get a set of DHLA45's instead. It'll run like a pig down low, not what you need with a smaller engine that struggles for torque anyway.

The chokes only limit the effective power band, if they are to small it will "hit the wall" and just not rev much harder.

SSS's only ran 28mm, 31/32mm should be fine for a good A12, my 1300 ran with 34's and even then could have gone smaller for more down low but it did rev well to at least 8k.

Bottom line, find someone who has experience tuning carbs, talk to the classic rally guys as they will have the contacts..

thanks for that yea my old datto ran 40's and it went fine but that was a number of years ago and i don't know what they ran.