Took the head off today and didnt see anything obviously wrong.

I've searched this forum and found a topic about how high the pistons should project out of the block and mine dont seem to be any different than maybe up to 2mm over the block face. The valves, spings and rockers all seem fine. When i take the rockers off, the guides dont seem to have any play in them so i dont imagine the valves wobbling.

The head gasket was mounted correctly so it couldnt be that either.

How hard are the followers supposed to be? i.e i can push a couple of them down maybe a millimetre but the others are solid. Is this because they are only compressible until they fill with oil?

I roughly measured the height of this EFI head against my old carb head and it seems to be about 1 millimeter or so shorter in height. Surely this isnt too much material taken off?

Can anyone tell me what the uncompressed height of a normal spring is?

When i first ran the engine (before knowing it had 2 bent valves in the head) it obviously sounded like a lawn mower but i switched it off after 2mins messing max. Now taking the head off today i can see that the bent inlet valve had been hitting the piston causing a very slight i.e about 2 millimetres across mark. Could this have damaged either the small or big end bearing? I only ask as all i can think of is that the piston is able when revved to rise much higher out of the bore and actually is hitting the combustion chamber.

I think my next plan is to mock re build the engine but not tighten it up fully and use some plastercine on the crowns, put the belt on, use 19 mm on the pulleywheel for afew turns and see if there are any imprints.