Thread: Cylinder 3 not behaving

Hi
Sounds like the plug lead has died. Try swopping #2 and #3 leads at both the plugs and dist cap. If the miss is then on 2 it is the lead. If it is still on 3 it could be the plug. Try changing one thing at a time though so that you eliminate one thing at a time.
If neither of these changes finds the fault inspect the inside of the dist cap for arching or cracks. Change if necessary.
After all that check the compression on all cylinders to see if #3 is low.
Hope this helps.
Phil

If the above comment don't work pull the plugs out and do a compression test. if a fault is there then first check ur valve clearances. if ok be ready to do some major surgery.

Cheers Rod

Timj had the same problem @ skinfull trip a few weeks ago, turned out to be a head gasket problem, had bugger all compression on 3 when we used the crank handle.

The 2a wouldn't start at all since not long after my initial post. However, I got it started today.
Sounded a bit rough when I started it but it settled down to a good sounding purr with no miss.
When I took it for a drive everything was fine when travelling along but would start missing again when under excelleration.

Could this be a carburetter/fuel issue?

If it's consistently misfiring on only one particular cylinder, you can rule out carburettor or fuel as culprits.
Could be ignition or compression, as stated.
Check the easy things first (golden rule!). Spark plug, lead, cap etc.
Then see if there's enough valve clearance, if OK then do a compression test - could be a burnt valve.
Some engines get sticky valves that stay open so no compression.

If it wouldn't fire at all the problem is getting worse, so it is probably the ignition system given that it was only No. 3 earlier.

What type of rotor arm is in it? There are cheap and nasty ones on the market, which cause problems. If you have an old Lucas one, try substituting it.

Give the whole low-tension circuit a thorough inspection including the earth wire on the contact-breaker base-plate; check for loose wires; broken strands, etc.

Check the colour of the spark at the plugs; it should be strong and blue any tendency to yellow, or weakness could mean a dodgy coil.

When you are satisfied that the ignition system and the compression pressures are OK, then investigate the fuel system,

Cheers Charlie