Right its probably just tappets your hearing at 0.25 they can be quite alarming to people used to hydraulic and OHC bucket and shim. 0.2 if you prefer a quiet life.

Score will hold the oil so thats consistent with the blowing smoke

The brown is Varnish from dirty oil and worn rings and is nothing unusual to see on a 2cv, usually 2 rings on the pin. The varnish can make it difficult to get the gudgeon out. polish it off with rubbing compound and make sure the well cleaned pin is not loose in the small end. If there is black deposits on the bearing surface ( ie where its inside the little end) then that's going to need further investigation.

Dave,
with the heel of your hand ( gloved if you're a wimp ) and listen for the 'clack' sound which a worn big end would make.

Ah yes,I remember now .Forget the hammer

I have disregarded the old barrels and pistons as I have new 9.0:1 from ecas going in. I will post some pics if what I have found in the week as I'm off for roast lamb in a bit round the in laws gutted about the stud, the detonation area of the head with the scored barrel is BADLY coked! I rekon it's been burning oil a while, the piston has bits missing where the gudgeon pin goes through the circlip fits into the piston.

Dscf0205 by Sean602, on Flickr

thats what pinking does to the head


Dscf0208 by Sean602, on Flickr

and piston

Many thanks and that's exactly what mine looks like!

Do not understand why the pinking has got between the joint of the head and barrel in top photo... Do the pitting on the piston match (same area) as the head? Both pistons and heads the same? Bottom picture shows the piston has pick up on it below ring (temp seize)???

its always opposite the spark plug as thats where the un burnt mixture is when the volume reaches critical pressure.

dont know why it gets in the crevice but once it starts it acts like a plasma cutter. possibly due to the localised heat build up the head warps and the increasing pressure finds the weakpoint in the joint. well spotted piston skirt "wiped " on the barrel due to heat breaking down the oil film "Partial seizure". Note the land between top and 2nd comp ring both rings had been trapped and so the blowby was phenomenal.

yes piston and head are the matching pair the piston is off the engine and resting on the pushrod tubes of the head on the post mortem table while the rest of the engine is still going round Snetterton as the pic is taken

all because the engine builder had listened to the pearl of wisdom "you can advance the ignitioon by5* for extra power" -half an hour in to the 24hrs and all that extra power had the car limping home spewing oil.

My old barrel and piston above ! Looks like someone has covered the top of my piston with "soul glow" (a childish defence to an 80s Eddie murphy film called coming to America I think) in other words a wet look Afro. And the scored barrel