OK, one of my other cars is a 1972 Spitfire 1300cc. Got the head reconditioned about 3 years ago. She is now burning oil and getting a bit emulsified. Compression is down by 40 psi on all 4 cylinders (pretty much the same on all four which I think is a bit odd) . With your collective knowledge is it time for a recon/rebuild engine, or could it just be lapping the valves in? Or cylinder head gasket?
Thanks for any advice.

Could be a number of things. Give it a service, check the gaps etc and that might thow the problem to light.

Assuming its doesn't do Startrek mileage top end sounds OK -I'm guessing you will have redone valves etc with the head, oil will be from bottom end - worn bores/pistons engine will be ageing andshagged out.
Most unlikely for head gasket to drop all 4 cylinders in my opinion.
atb
Mike

Sounds like piston ring problems, was it also rebored or had new piston rings fitted ? if so it sounds like the rings never bedded in.
it might be an idea before tearing the engine down to check the valve clearances as this would explain the low compressions.

These engines do get a bit of mayo in the cold weather, so I doubt that is an issue.
As all 4 readings are down, it could be the gauge which is playing up? check on another engine? and I take it you are doing the check with WOT?
The head torque has been checked, and it was retorqued after a few hundred miles (I forgot to re-torque mine, I was amazed when I did remember how loose the head nuts had got )

Are there any other symptoms?

EDIT re-read OP, rings could well be the issue, a hone and set of rings may well sort that. And while you are there a set of tri-metal BE/Mains and some thrusts......

[Edited on 25/2/12 by cliftyhanger]

Think about it over lunch: valve seat recession ?

was going to suggest the same things, did the head have unleaded seats fitted when it was done?

Drop of oil down the spark plug hole, if compression goes up its the rings

Yes the valve seats were replaced for unleaded ones. Would this cause a problem. I must admit I didn't check compression when I refitted the head so I don't know for sure if it has gradually got worse. I have used 2 different guages and they read the same.

possibly incorrect valve gaps or as said above drop some oil down the plug holes & recheck compression, if it gos up its rings, whip the head off & have a gander & turn the head upside down on the bench, poor petrol in the valve chambers, if it leaks away the seats need re lapping or at worst recut!

when does the engine smoke, startup/ tickover/ general driving or just under accelleration???????

To be honest it isn't that smokey. But it does seem to blow quite a bit when I take off the oil filler cap.
I tried the oil in the spark plug hole then retried compression and it wasn't that much higher (maybe 10psi higher).
I think it is time to take the head off and have a look see.
Thanks for the advice chaps.

hi there, pop over to the triumph dolomite club site loads off help there. try and find jod clark. he did have a few engines going for free. and he does know his ohv engines

terry

Update on the Spitfire.
After worrying about compression oil etc. the old girl started doing some very strange things, including stalling when going down hill.
Had a bit of a chat with West27 (lives round the corner) and decided something dodhy on the fuel front. She only managed a few pathetic squirts into a jam jar with the engine running. Fitted a new fuel pump, stripped and cleaned the Weber DGV carb and tuned her up on the 4gas tester....And she runs very nicely again.
Thanks to all for the advice and help!! Another 'classic' can stay on the road for another year.