Engine missing when cold.

[wanderinstar]

Until about a week ago I had no problems with engine. Apart from headgaskets. Would pull choke out about 1/2" engine would start first time and pull spot on. push choke in after about 2 miles . Hunky dory.
Then about a week ago the engine started missing every so often, not all the time. When engine warm, no problem. But why is it missing when cold?

[mike.perry]

Intermittent misfire. It doesn't seem to matter whether it is hot or cold. I find the only solution is to replace everything one at a time until you find a cure.
Suggestions, run the engine with the bonnet open at night in a dark garage to check for faulty HT leads or anything that sparks where it shouldn't. Don't stay there too long you might start to feel sleepy!!!!
Loose HT leads in the dizzy or the plug caps, loose plug caps on the plugs (I just had this with some cheap caps)

[MoggyTech]

Also check carb dashpot oil viscosity and level.

[bmcecosse]

I would also suspect HT leads/rotor arm/cap etc.

[Alec]

Hello Ian,

as it doesn't miss when warm, I would look at mixture, try playing with the choke a bit, and certainly ensure, as was said earlier, that there is sufficient oil in the dashpot.

Alec

[wanderinstar]

Hi Alec,
But it started doing it immediately, it wasn't a gradual thing. Lo and behold it didn't do it at all this morning. I do really hate intermittent faults. They really make my blood boil.

Roy , new leads, cap and rotor arm when new Aldon dizzie fitted not that long ago.!!

[Alec]

Hello ian,

the only reason I went for fuel was that it is OK when warm, and often electrical problems are worse when warm. I take your point about it happening suddenly, and another possibility is a sticking valve that frees up as the engine warms? Rare, these days, I know but it can happen.

Alec

[Alec]

Hello ian,

the only reason I went for fuel was that it is OK when warm, and often electrical problems are worse when warm. I take your point about it happening suddenly, and another possibility is a sticking valve that frees up as the engine warms? Rare, these days, I know but it can happen.

Alec

[bmcecosse]

Could still be faulty HT parts Ian - it happens - try swapping some for even 'old' spares. I was thinking dampness on the electrics which dried out when warm. Maybe try another set of plugs - maybe the plug contacts have been burned away ? I also considered sticking valve - but unlikely as Alec says, although I suppose just possible. Mixture is way over rich when choke is out so I doubt it's that.

[dalebrignall]

there have been some dodgy rotorarms check its clean

[wanderinstar]

Well whatever is was it seems to have gone now. I wondered about damp in dizzie cap? Started and ran ok on Monday morning and the same coming home tonight. Thank you for all suggestions though.