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MG MGB Technical - possible Pertronix fault

I fitted a pertronix electronic system to the 71 roadster a couple of years ago and it improved the running quite a bit. Lately the car seems to be hesitating and sluggish on low throttle openings but when I put my foot down it picks up OK. I know this could be caused by many things but plugs, leads and dissy cap look OK. Wondered if the pertronix could be starting to break down. Has anyone had this, Is there a way of testing them?
Thanks Trev
Trevor Harvey

Trevor - Anything is possible, but normally electronic devices fail suddenly and completely (one of the arguments against the all electronic fuel pumps). Your symptoms sound more like a sticky piston in one or both of your carburetors. also, visual checks of plug leads and distributor caps is not a real positive way to determine if there is a problem with them. A better check would be to replace them. Cheers - Dave
David DuBois

The Pertronix simply replaces the points, so if that were not firing regularly and consistently when the problem occurs you would see that on the tach by it flicking around. If the tach is steady and you can reproduce the problem at a standstil you can verify if the HT side is OK or not by clipping a timing light onto the coil lead and each HT lead and watching the flashes. If the coil lead become erratic it is the coil. If the plug leads are erratic but the coil lead is consistent it is the cap or rotor breaking down. If all are consistent check the timing is where is should be and not leaping about, and if that is OK then it is probably fuel. Hesitation on acceleration is a classic symptom of insufficient oil in the dampers, or possibly a vacuum leak on the intake. If you unscrew the damper cap, lift it up, press it down gently, and can feel the resistance of the oil before the plastic cap reaches the piston cover you have enough, how much before tells you how much of a 'reserve' you have.
Paul Hunt

This thread was discussed on 25/03/2009

MG MGB Technical index

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