how long to bake a 5 egg sponge for?

[mausmaus]

used the 'weigh the egg' method for a 26cm round tin.
in the oven now at 160 (conventional)

That's way too low. Turn it up to 170 or even 180, since it's a big tin and check after 40 minutes.

thanks, have turned the heat up.
low and long like a big piece of meat