cosworth engines are prone to leak oil .
they are shitty when it comes to the design of the front oil seals,i mean there is an o ring,sim ring,rocker cover casket,,and the half moons..i mean..herrooo.stupid design.buuut...
make shure all the surfaces are clean and straight..maybe do a slight reface on the rocker cover.
im gonna try out a new sealer that i bought at my work.its supposed to be verrry good.