Mgb misfiring and spitting fire!!!

[gt67]

Started my mgb this morning. After a minute it started to misfire badly, having very little power. If the revs increased, the car would then sometimes backfire and on 2 occasions a lick of flame from the the exhaust.

I was about to switch off, when the car the ran completely normally and I completed an hours journey with no issues.


Later in the day,, it started a much smaller misfire which then cleared.

Any ideas, thanks everyone.

[gt67]

Actually- the misfire has come back! Have tried replacing dizzy cap and ht leads. No luck

[Richard Moss]

Have you tried a new rotor arm?

[Luxobarge]

Yep = another case of a cheal chinese rotor arm would be my guess, you need to fit a good quality red one.

[History]

Have you got a mate with a similiar ignition coil that you could borrow.

Because of badly made rotors, all rotors are becoming suspect.

Check the rivet if it has one. I have seen the revit close to the metal clip that holds the rotor on shorting the ht to earth.

I didn't see many bad rotor arms. And because they don't actually wear. I rarely changed them.

My car 41 year old rotor.

[kevin]

http://www.accuspark.co.uk/distributors.html

My standard response to ignition problems on old cars

Kev

[Luxobarge]

http://www.accuspark.co.uk/distributors.html

My standard response to ignition problems on old cars

Kev

Good shout, or buy just the rotor for a fiver, job done - those are good quality ones, not the riveted carp ones that are not even worth using as paperweights.

[Fatbloke]

Hmmmm. could this be the problem on mine I wonder? occasionally misses under load. Perhaps I'll buy the expensive rotor before stripping down the carb then.

[kevin]

Hmmmm. could this be the problem on mine I wonder? occasionally misses under load. Perhaps I'll buy the expensive rotor before stripping down the carb then.

I had all sorts of running problems with my Singer early on, even bought a brand new (old stock) carb which was very expensive.
Turned out to be the 1970's Lucas electronic ignition system breaking down, good old girl decided to finally give up the ghost in my garage eventually which was convenient.
I was due to be at a local car show shortly after it packed in so as I was a bit stuck I plumped for the accuspark unit (£58 delivered), took 15 mins to fit and time up and it transformed the running, combined with the new carb the car runs smooth as...
sods law but just after I bought the accuspark, a brand new old stock original distributor fell in my lap complete with original rotor and cap, I did plan to fit it for originality but the car runs so sweet it seems a daft idea, still waits on the shelf though.

Kev

[History]

Carb faults tend not be misfires.

Electronic ignition.
For 50 years or more the contact points and condenser worked quite well.

Points have an advantage of being repairable at the side of the road with a blunt screwdriver. Electronic ignition is not 100% reliable. Seen a few go pear shaped.

I have heard many stories of how much better the engine runs on electronic. But was the original system working correctly. Also electronic dizzys still need servicing with a sqùirt of oil.

Do check out the ignition coil.

May all your misfires be cured.

Bob