misfiring

[iddy]

I've been pulling my hair out this morning.
My wife told me "the car's not right". Sure enough she is only firing on three cylinders (and my wife ). Nothing happening when I remove the plug lead on No2, engine still ticking over, but lumpy.
Thinking it was a quick fix, I changed the plug and lead for known good parts, but still no joy. I then changed the dist cap and rotar arm - no luck.
I swapped No2 lead and plug with No 1 lead and plug, just in case known good parts were'nt good - same problem. Then like a dolt I unplugged No2 lead and tried to put a new spark plug in while engine was running - why I did such a stupid thing I don't know, probably down to frustration.
Anyway, still not firing. Is it something serious? Any help appreciated.
Iddy

[iddy]

I should also add the plug isn't oily.
Iddy

[alfrednewall]

Hello, Im a little fustrated this morning with my morris as well. When I try and start there is just a whering slightly grinding noise from the distributor and it wont start. Any ideas.

I had the same problem as you, running on three cylinders. I replaced all the spark plugs and she was back to normal.

[chickenjohn]

If you've gone through the ignition (plugs, leads, points/dizzy cap, etc) try a compression test on all cylinders. Might be a burnt exhaust valve.

[cliff]

have you tried one of those little yellow sparking thingies that you plug between the ht lead and the plug - it gives you a visual indication as to the strength of the spark.
otherwise as chickenjohn said, try a compression test.

[iddy]

Well, (finally ) did as suggested and bought a compression tester.
Have now changed duff head gasket and all is well. So a belatedly thank you for the advice.

When setting the valve clearances I could'nt use a ring spanner because it kept catching on the rocker arms so made do with an open ender. I'm going to grind down a ring spanner to fit because I'm always worried about rounding nuts off.

Iddy