Compression too high.

Aaargh. Well unless it's a JCB and decided to run backwards :-)

No, the rise is due to the much larger inlet time. Original Compression*(1-sin(45))/(1-sin(60))xK where K will be greater than 1 as there's nowhere for the heat to go. Substitite whatever the relevant numbers for your engine are.

That's what I thought, but the guy reckons not.

The head was reconned and fitted within 2 weeks of the belt breaking.

Apart from the compression readings, all the info I have is what I've been told. I've never actually heard the engine running, or seen it smoking. The car is in the w/s next to the toolroom where I work, but most of the work on it has been done in the evenings after I've gone home.

If the engine is still in one piece, I might ask him to start it up today so I can hear it and see the smoking problem myself. I'm with you. What I'm being told doesn't really add up. Mike.

The obvious answer would be that one engine has the combustion chamber in the head the other in the pistons, were the pistons changed due to damage from the valves if you have the same head?

It doesn't seem necessary to postulate unlikely solutions such as the wrong type of head having been sent back and that A) actually fitting the block and B) the son not noticing the difference when the symptoms are easily explained by a simple fitting error.

We don't know exactly what engine type but the 8v had a CR of 9.8 and the

16v 10.5. Normal cranking pressure for an engine with about 10:1 CR in good condition could be up to 200 psi. Advance the cam timing until the inlet valves close at BDC and that would rise by about 20% to 240 psi. Add in a head skim and excessive oil in the bores and the rest of the gain in cranking pressure is explained.

If the inlet manifold is full of oil then the answer is obvious. Recheck the cam timing, clean out the inlet manifold and the block breathers and it should be fine again. No conceivable fault with just the valve guides or stem seals would possibly explain such a large rise in cranking pressure so the problem has to lie elsewhere.

I can see someone screwing up the timing when fitting it once but doing it twice? It's not like Vauxhall keep this information top secrete with an armed guard. Ockham's Razor dose say the simplest solution is normally the best (ok that's not actually what it says but we know that it's close enough) and I guess numpty fitter is a simple solution.

Twice is easy if you time up from the wrong mark. BTDTGTTS.

If you're doing something wrong and don't realise you're doing it wrong it doesn't really matter how many times you check it. You'll still get it wrong. About ten years ago I came across a similar case. A Lord somebody or other had taken one of his rare car collection, A Lancia Gamma flat 4, to a dealer for service and cambelt change. It ran ok afterwards barring a slight tapping noise but before he had time to take it back to get that checked it expired and had to be trailered home.

Not trusting the first garage to own up to any mistake and fix it for free he took it to a Lancia specialist who removed the engine and sent it to me for an independent expert opinion on what had gone wrong as it all looked likely to end up in court. Wasn't hard to spot. The cam timing on both banks had been set up relative to the ignition timing mark on the flywheel and not the TDC mark. Result was cam timing about 30 degrees advanced and the inlet ones were just tapping the pistons. Not enough to stop the engine running initially but after a while the stress broke a rocker and then it did all grind to a halt. An easy enough mistake to make if someone was rushing or not very familiar with what was admittedly a rare engine. I'm sure someone could arrange to do the same on an Astra without too much difficulty. If they maybe plumbed a breather hose or two in wrong to boot you've got all you need for the OP's symptoms.