2.25 Petrol driving me mental

I keep getting (what I think is) oil over plug no.3
I took the head off, replaced the valve seals with good quality seals, lapped the valves in etc and cleaned up the head.
Here's a photo of the plugs just taken out in order: http://www.ledgard.co.uk/images/plugs.jpg

• Valve guides do not appear worn
• Compression test= 1)122 2)129 3)131 4)123 (my comp tester is the cheapest money can buy and has been dropped a few times)
• I put oil in the cylinder and tested again - no compression increase
• Have tried two different dizzys (electric and one with new points etc)
• Have tried two different coils
• Have swapped plugs/leads around & the fault stays at no.3
• Have tried both LPG and Petrol

After five minutes idling it starts popping intermittently and missing on no.3

Any suggestions!? What am I missing?

get a leak down test done on it; you may have a crack which opens up when hot.

I hadn't thought of that. Don't suppose you can rent them?

dunno, yer might or you can make one. i seen the plans fer one somewhere and i think it involved an old spark plug and a tyre valve avec pressure gauge

ok I googled it..I reckon I can knock one together for £15!
Forgot to mention there is no pressure when I take the rad cap off, never has been while I've owned it. It doesn't lose water though.

When I took the head off again there was oil all over the back of the intake valve for no.3

Took the head in for a crack test yesterday..got it back and there is nowt wrong with it.

If it was the rings would I have oil over the back of the valve? and if that is the case wouldn't it be on the back of the exhaust valve too?

how about the valve guide? Oil passing the rubber covers and running down the valve guide?

The Mad Hat Man said:

how about the valve guide? Oil passing the rubber covers and running down the valve guide?

Click to expand...

The guide doesn't seem worn & it's no different to any of the others.

Have you put the head back on and tried it again ? with particular attention to valve clearances

You say you've swapped the leads around etc, but are you deffo getting a constant spark at no 3?
Mine was intermittently missing on no3 and I eventually tracked it down to a distributor cap minus the central button. How it worked at all, i'll never know!

If you have oil behind the valve head it has to have come down the stem surely? If it's an inlet valve though surely it will be contaminated with petrol? Unless it was majorly leaking oil it should have been burned off. I wonder, was the crack testing on the face of the head only or was it over the whole head, ie the valve stem surrounds which couldn't be accessed because of the valve stem oil seals?

More questions than answers I know, but I look forward to hearing how it turns out and how you eventually sort it!