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MG Car Repair/Petronix for MGB


QUESTION: Barrie,I took your advise and installed the +ground unit in my '67 MGB-GT. I had to drill out the holes on the sensor plate to get it to fit over the studs.  Did you have the same problem?  I routed the wires counter-clockwise in the distributor; however, they tend to stray away from the plate and towards the rotor. Should I be concerned about them rubbing on the rotor? I installed the unit with the distributor mounted on the engine, so access is difficult.  The car started, so at least I got over that hurdle.

ANSWER: Hi Larry.  My current MGB has a Rover/Buick V8 engine so the Pertronix unit fits in a different way.  It did not need any drilling.

My 1955 MG TF1500 has a similar distributor to the early MGB and I did find it necessary to clip the wires so they do not foul the rotating magnets as they rotate.  You must still remove the distributor cap once a year to lubrucate the advance mechanism, so just keep an eye on those loose wires at the annual service.  

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QUESTION: I don't follow what you mean by clipped.  I have never lubed the advance weights on a regular basis.  To get to them it seems that I would have to take off the distributor plate (two screws) that the Petronix sensor is mounted to.  The vacuum advance attachment will probably make it difficult or impossible to remove the plate unless I take off the Pretronix sensor.  I really don't want to do that!

You should have received a small zip tie as part of the Pertronix kit.  It is essential to clip it tightly round the cables just inside the distributor where the wires exit through the grommet.  This stops you from accidentally pulling the wires tight, when they might be damaged by the rotor.  

Once a year you should remove the rotor arm and put 2 or 3 drops of oil down the hole in the middle of the spindle.  Otherwise, the advance mechanism may seize solid.  There should also be a gap around the edge of the baseplate (or a hole where the condenser used to be).  You should inject another 2 or 3 drops of oil through the gap so it lubricates the advance weights.  Do not over-do it.  

The vacuum unit should not be lubricated because oil may rot the rubber diaphragm inside the capsule, causing it to fail.  

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Barrie Jones


MG Sports Cars from 1949 to 1980 - Including MGB, MGBGT V8, TF1500, TF, TD and modern Midgets. I also specialise in SU carburettors, Lucas wiring, suspension, steering & brakes.


I have owned my 1955 TF1500 since 1966. Technical specialist for the TD and TF with the MG Car Club T Register. Also owned 20 MGBs and currently own an MGBGT V8. Written 3 books on MGs and produced a DVD on how to strip and rebuild the TD/TF gearbox.

MG Car Club.

Barrie's Notes on the 1953-55 MG TF (author). /=====/ Barrie's Notes on the MGB (author). /=====/ Barrie's Notes on the MGB GT V8 (author). /=====/ The Essential Buyer's Guide to the MG TD, TF and TF1500. (author)

M Phil, C Eng, BSc (Eng).

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