So long as the oil cooler is in sound condition and not sans fins. Then its

Thrash
heat
Thrash
more heat
Thrash
expand
Thrash
partial seizure
Thrash
busted rings
Thrash
broken piston
thrash
bang
death

Stay conservative and your engine will last forever. You need to understand metal, friction, lubrication and heat. Most don't which is fine but ignorance have killed many A model engines prematurely.
So please continue to drive like an old man. Don't forget to put a hat in the rear window.

+1 to Viking's advice ^

I guess that, like me, he's had to put the pieces back together after someone's believed that the only way to drive an A series is with right foot buried in the bulkhead.

Some of the sweetest engines (and also gearboxes) I've known have belonged to drivers who don't thrash the machinery constantly.
Contrary to certain rumours, as and when asked to, those engines would usually outperform the ones that had been caned without mercy.

ken.

Ah the "kill or cure" pilosophy

Usually the former, rarely the latter without some mechanical intervention.

Sean

I think i'm going to take a bit easy and have the odd blast now and then

right back to the compression readings - so, choke off, throttle open

and i got 155psi on the OS & 180psi on the NS

so, better compression but i'm still concerned about the difference.

smells like oil seems to be burning for half a minute after a cold start, not after that though.....it's an old engine i guess...

cheers
Will

Have you done the tappets? they can affect the compression.

if you have it looks like its quite tired

still new rings and at worst barrels and pistons and should be a happy bunny

in the meantime beg steal or borrow an engine so you can get the cars one stripped for a look inside

Sean

Cold start with blue smoke is common in older engines. Worn valve guides and valve stem seals allow small amounts of oil to enter the combustion chamber after turning the engine off. Starting cold, after a few minutes the oil is burned off and hopefully no more blue smoke. If it continue maybe piston rings are also worn allowing oil from the sump to blow past. The only way to fix it is to take heads and barrels off. No need to take the engine out. OK its an Ami but all guards off and voila easy access.
The compression test to me show too much variation but just on the limit. If the 155 psi drops below 145 psi soon, I would investigate. For the moment, I wouldn't worry too much.

Not sure I agree.

Some of these old M4 engines (if this is what is fitted) don't have valve stem seals (like other Citroens of the period eg DS) so will by their very design smoke a little bit on startup and on the over-run.

Anything over 125 Psi is fine. I've seen cars running with less than 100psi, not brilliantly mind but still running. If Willami is running the original engine these only have 7.75:1 compression anyway.

Is usual that the exhaust valves burn out on these M4 engines if you are using them everyday with the high octaine fuel available now, so keep an eye on the exhaust valve gap.

Maybe right. I had the M28 9.0:1 in mind due to the 180 psi. Didn't think that M4 would reach 180 psi being an old engine.

will's ami is M28, i think.