Help (please)! My partner had a problem with his 1968 Volvo Amazon Estate car at the weekend. It started to feel lumpy, like it was running out of fuel & it started to make a funny noise by the filler cap? Anyway, we pulled over & he managed to go a bit further up the road but then the engine cut out & we had to call out the recovery service. He & a neighbour have tested the points etc & have just changed the coil but it's spitting out through the carbs & he thinks it might have dropped a valve? Any ideas what to do next? I guess a compression test is needed but is it terminal as far as the engine is concerned? It has been using a lot of oil recently... : ( Thank you! 

No reason to rebuild the engine if it is only a bad valve....just rebuild the head, faster cheaper.
BUT poor compression on one cyl is not always a bad valve/valve seat, could be a worn cam, bent pushrod (unlikely) bad piston etc....a full rebuild will catch all of that of course, but if you can work out exactly what is wrong a little head/valve job etc will get you back on the road faster, with less disassembly and less $$$. Good luck.
--
Patrick, '68 220 (used to drive 240s) '53 GMC 4104

regardless of the condition of the lower end of the engine I think you will find the valves badly receded into the head and in need of valve seat inserts.

It's been a long time. Check that the phenolic timing gear hasn't been stripped of some teeth. Easy to remove the timing cover from front of engine for visual inspection & replacement. Follow the manual for alignment and orientation of the timing gears. Did this, oh, about 32 years ago.

Thanks for all your help with this. The compression test showed that the 4th valve is down & my partner therefore suspects it's faulty valves or piston rings. He's decided to SORN the Volvo, buy a small van & eventually use it to get the engine rebuilt by a relatively local garage.

Please pull the valve cover and do a visual of the valves. A broken valve is easily detected and fixed.
--
My name is Klaus and I am a V ♂ lv ♂ holic

Another reason for spitting through the carburetor is a bad exhaust lobe on the camshaft.
You can check for this by measuring the lift of each valve (difference between open and closed)
from the top surface of the head. If one or more is different, time for a new cam.
Normally this would NOT keep it from running but would make it run poorly and spit through
one of the carburetors.
It is NOT detectable by a compression check.
--
George Downs Bartlesville, Oklahoma

Some of these symptoms could be caused from the motor being out of time. Was the timing checked? If that is okay or if you can't tell because it won't run at all, make sure the distributor isn't loose. Meaning the clamp that holds it in position is tight.

If that seems in order then a compression test will tell you a lot. Near equal compression in all 4 cylinders is more important than a high numberin any one or all. A broken valve floating around in a cylinder is going to be obvious. There isn't normally room in there for anything except fumes. A bad reading in any cylinder is more likely a burnt valve, bad valve seats or maybe a broken spring (easily detected by removing the valve cover). Spitting out through the carbs is another hint that there may be a bad intake valve somewhere, although trouble usually comes from the exhaust valves first. Heavy oil consumption can be a sign that your valve stems are not sealing correctly. Heavy damage can occur to the seats if they are still the type that require a coating of lead or a lead substitute to protect them.

Removal of the cover, then the head will give a good visual on the condition of the valves. Things should be clear then. This will also give you a chance to inspect the cylinder walls for any obvious scoring. The head is probably the easiest thing to repair and replace. Damage to the cylinder walls, cam shaft or crank-piston assembly is a much bigger problem.

Oh and just for fun, check the oil at the dipstick to be sure there is no water in it. That will be obvious as water and oil don't mix. Water there means a crack in the block or head somewhere. Not Good.

Any repairs to the head should begin with it being checked for cracks by the shop doing the work. Any new seats installed should be hardened to allow for the use of non leaded gasoline.