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Intermittent mis-fire


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I haven’t touched the vitesse since lock down but it’s time to start again. The car has a very intermittent mid-fire, usually on a decent run when the car has been running at constant revs, or when going up an sharp incline. I’ve checked the tank, it’s clean, I’ve installed a fuel filter, cleaned the fuel pump, replaced the fuel line, cleared the crap out of the carbs. Ignition timing checked and it’s good, spark plug colour good. The car can take a little cranking over to start but I pump that down to a feeble battery. I keep thinking the electronic ignition (it’s the cheap nasty one) or coil. I keep thinking about treating myself to the Aldon one as that’s what I used on the spit and gt6.

Any pointers what I should check or change next? It’s an annoyance and I’d like to fix it 

The one thing I know needs checking is the tappet settings (it’s set to a standard cam of 10thou) and in the box of receipts I was given by PO is a spec sheet for a different cam, it list 12 thou and 14 thou (inlet and exhaust)  would this cause any issues?

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tight tappets can give a hic up as can over advanced , plugs with an R in the suffix and weak mixtures 

and there are many a cheap electronic unit that become problematic,  some are fine 

some like plugs with an R in but ive found they are awful and they dont suit the low HT we have .


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I’ve checked and cleaned the spark plugs, no improvement so I replaced with plugs from the club, likewise the leads and the dizzy cap. 
It’s a real annoyance as i can use the car and it’s fine, then I use it and it mis fires. It’s usually only one miss so petes description of a hiccup probably is best, normally you can feel it more than hear it. 

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Have you got the preferred red rotor arm rather than the old black riveted arm?

Is the coil too hot? An indication it’s not happy. It will be warm, but not scorchio! 

Check all the electrical connections in the ignition system including the earth inside the dizzy.

Good luck!


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I will check the earthing as suggested, I know the earthing on the car isn’t the best as a couple of the earth straps were in very poor condition.

I have a new set of points, arm and condenser (tssc supply) so I could revert to original set up.
I just need to find the excuse to use the car and try and find the fault.

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