Tony- There are a number of on line spoke calculators. I often use the DT one, linked below. Depending on the spoke nipple washer you might add 1mm to the rim's ERD.
http://www.dtswiss.com/
> All,
>
> I need to lace a pair of ('50's) Campagnolo Gran Sport large flange hubs
> to a pair of Weinmann Scherens tubular rims. They are 32/40 spoke pattern.
> I plan to use washers under the nipple heads. Where can I get the proper
> spoke length information?
>
> Many thanks.
>
> Tony Taylor
> Manchester, NH
>
>
>
> _______________________________________________
Andrew R Stewart
Rochester, NY