no it still runs the same when you take those 2 leads off, my friend who is a mechanic said that it sounds like bent valves because there is marks on the pistons where they hit when it snapped a con rod. i will try n borrow a compression tester.
cheers

some sort of spark issue or some serious head problems,

get a compression test done this should help you out a little more!

doesnt affect it when you remove both plugs at same time?

sounds like its running on 2 cylinders

yeah i re built it, one of the pistons on my old block frew a rod so ive got another bottom end re built it its misfiring dosent affect the way its running if you take both the middle spark plug leads off, hard to start dies when you rev try to rev it throwing loads of black oily petrl out of exhaust.
cheers

woudl be no compression onf the affected cylinder.

did you re-build it? what are the symptoms?

what are the symtoms of having bent valves on a 16v corsa im having problems with my re built engine and ive been told it could be bent valves.
cheers