Leave the A470 at the derelict Cross Foxes pub onto the A487, a very quick road for 4 miles then a turning on the right the B4405(easy to miss turning).This road is a real tester if taken at speed,plenty of good bends on an excellent road surface,especially around the Tal Y Lyn lake. When you hit the main road(A493) turn left and head toward Tywyn. Just before Tywyn on the left is an icecream factory,well earned rest,and the best icecream in Wales.
From Cross Foxes to icecream factory 16 miles voted by a group of seven as the favourite road in the area, due to lack of traffic and quality of corners.
Turn left onto the B4405, heading East-ish. This is a nice road up a valley, and near the end there is a very pretty lake with some cafes on the edge.
At end of B4405, turn left onto A487 heading north toward Dolgellau.
When i took this route, around 11am in late July 07 it was practically deserted.