Thread: Inspecting cylinder block for wear - whats this?

Hi

looks maybe like a squashed lifter hat to me.check to see if any are missing.

Originally Posted by 91ramjet

Hi

looks maybe like a squashed lifter hat to me.check to see if any are missing.

the caps that sit on top of the lifter springs right? Thats what I thought it looked like - most likely. They are all accounted for but last time the head came off it was at the mechanics workshop. Maybe when they put the rocker back on they thought they were missing one and didnt realise it had been knocked down - or couldnt be bothered to undo the head again to fish it out!!

yup X2 for an old valve lash cap.

JC

ok so squished valve cap sitting under pushrod of an exaust valve would raise the pushrod higher than normal and cause the valve to not shut properly therefore creating the potential for extra smoke out the tailpipe?

a good guess? I sound convinicing

As for the cylinder walls and piston crowns whats the basic check for wear?

i'm no expert but i think i saw some crosshatching (sanding marks in a sort of diamond formation) in one of the photos which means it has hardly worn at all and if there is no lip at the top of the bore it will all look good

cross hatching is evident so assuming the greaser (or swarfie) who built it up was paying attention to best principles (he wasnt doing best practice or you wouldnt have found a valve cup in the donk)

you should be right leaving the bottom end alone.

what you can do to gauge the pot condition is to grab a piston ring, put the piston at BDC and then using a tube push the ring down the bore in small increments and measure the ring gap with a set of feeler gauges.

you can also do the same thing with a set o bore gauges if you have them and a decent set of micrometers.

the images arent up to the quality needed for an over the net diag BUT... I suspect that the problem has been nailed, the remnents of the valve cup was stopping the followers action and preventing correct operation of the exhaust valve.

the question is how far are you prepared to go to prove the engine?

Originally Posted by manic

ok so squished valve cap sitting under pushrod of an exaust valve would raise the pushrod higher than normal and cause the valve to not shut properly therefore creating the potential for extra smoke out the tailpipe?

a good guess? I sound convinicing

As for the cylinder walls and piston crowns whats the basic check for wear?

The would be mechanic who left a lash cup under your pushrod, I assume would have adjusted the rocker arm to suit. So your valve would have worked as normal, check the adjuster on the rocker arm and see if it similar to the rest, Regards Frank.

Originally Posted by Blknight.aus

cross hatching is evident so assuming the greaser (or swarfie) who built it up was paying attention to best principles (he wasnt doing best practice or you wouldnt have found a valve cup in the donk)

you should be right leaving the bottom end alone.

what you can do to gauge the pot condition is to grab a piston ring, put the piston at BDC and then using a tube push the ring down the bore in small increments and measure the ring gap with a set of feeler gauges.

you can also do the same thing with a set o bore gauges if you have them and a decent set of micrometers.

the images arent up to the quality needed for an over the net diag BUT... I suspect that the problem has been nailed, the remnents of the valve cup was stopping the followers action and preventing correct operation of the exhaust valve.

the question is how far are you prepared to go to prove the engine?

Happy that there is crosshatching, no lip to be felt, ran finger around all the walls and they all feel smooth didnt notice any scrapes.

On the piston crowns I realised that the faint marks I could see were circular and evident on all crowns, some a bit more than others but all positioned to match the valve openings on the CH. Is that normal for the valve openings to mark the piston tops slightly?

The ring gap is with feelers is a good one, but yeah your right I'm about as far as Im prepared to go to prove the engine. I'm happy that it all looks normal.

I'll use a blade to scrape any gasket remnants and wipe down with some meth spirits, put the gasket on dry and get the head back on.

Thanks.