cam pulleys
 

is there a special way of undoing the bolts on the pulley or is it just put a spanner on the cam and a allen key in the end as this is what i done on three os them and it went fine but the last one wouldnt undo wat so ever even had someone else to hold the spanner still

the strange thing is that on the head there is a mark which looks like where someone has tried before and dented the head

i cant get it undone and need to to get the head off

any help would be great
cheers

put the other pulley on wrap the cam belt round them both and around a free wheel/pulley and clamp with molegrips so cam belts really tight.