fluffyninja

Something that occurred to me after discussion earlier. Why isn't the engine starting? Is it because the cam has lifted due to the cracked caps and you aren't getting valve lift or is it because the cam isn't turning because it is seized? Might impact on the state of the bottom of the engine.

I'd taken that black marking at the #3 position as being just a streak of dirty oil from somewhere but possibly not.

My hunch and really am in the realms of guesswork now is that it has been tightened in the order #5 => #1. That's why #1 is so black. It is still clamped properly but they've progressively lifted from #5 forward and hence distorted the loading in the bearing, caused lubrication breakdown and seizure. An awful lot to infer from a photo though!

lower

There is also the possibility that the plug loosened and the coil pack over heated because of over heating of the camshaft bearings.

oxhouser

If you dropped a valve and it contacted the piston it could do that kind of damage
Check for witness marks on the piston crowns and check for play and uneven piston position at TDC if that's ok then you need to check the head, chances are its mullered as the cam journals are bored as a set so just fitting new caps might not work

fluffyninja

That'd be sudden catastrophic though. The heat signs on #1 journal show it has been running in some distress for a while
100% correct about the cambores/matched set thing

unclefester

It does start, it does run but it sounds 'strained' at tickover. The noise sounds like very severe TCT as opposed to anything overly mechanical.

oxhouser

Could be a blocked oil feed to the effected cam journal, can you see signs of pick up on the bearing surface, I'd be surprised if it got hot enough to do damage by just a loose coil pack as long as the oil feed was ok

eSeM

This was the coil pack that failed:

eSeM

Need any bits sand blasted?

fluffyninja

That suggests the bottom end is free but top end is doing its best to seize. If the top end goes solid there's a good chance it'll twist the cam sprocket off. The tct you think you are hearing may be the chain loading going through the roof as the top end is being forced around against its will

unclefester

Yep that was my thought based on the noise it made - still you'd not have thought the noise would equate to the physical damage.