does anyone know how to tune twin webbers?
its on a 4 cylinder.

Yeah. You need a carbie balancer to adjust idle and fuel mix between the two carbies.

First you need to make sure that the jetting and emulsion tubes are correct for you application. Most carbie tuners would have a chart with the recommended jet sizes and emulsion tubes for a given engine size.

I used to run an 82 KA Laser 35-75 Cam, 10.5-1 comp ratio,with a single 45MM DCOE Weber instead of the twin hitachi carbs and that used to blow VC commodores!!!!

I'll have a dig around and see if I can find the Weber manual that I used to setup carby.

Do a search with google or yahoo.
I found some docos on there a few years back.