1972 MGB GT – Part 2 – Lights, Ignition System and Misfire

As mentioned in my previous post, on the journey back from Heathrow, the car had a slight misfire which was more noticeable the next day.

The MGB GT has a twin carburetor, where one carburetor feeds the first two cylinders and the other the second two. As the air filters looked quite old and the misfire sounded like it was on a couple of cylinders I thought I would check them first.

As it turned out the rubber seals around the inside of the K&N filters had completely split, partially blocking the air filters.

Before going down to pick up the car I had ordered a service kit from the MG Owners Club, as the previous owner had told me it would be due one soon. The service kit came with two standard air filters. Though they are designed to go in the standard air filter housing I briefly replaced the K&N filters with the new standard filters to see if it would make any difference. I also gave the carburetors a quick visual check and oiled the accelerator connections.

Replacing the filters did not correct the problem so I proceeded to check the ignition system.

As it turned out there was several problems, the points were corroded, the distributor cap had worn points and corroded lead connector points, the ignition leads were corroded and damaged, and the spark plugs looked like they could do with being replaced.

As the service kit I bought came with a new condenser, points and spark plugs, I fitted these first and ordered new ignition leads, distributor cap, rotor arm, ignition coil and air filters.

In addition to the misfire, when bringing  the car back up to Scotland, the window wipers had stopped working around half way back. Checking the handbook I quickly found which fuse had blown. The same fuse is used for the heater blower, which appears to be the problem.

As there was no spare fuses in the fuse box I had to repeatedly stop on the way back to clear the screen. As the fuses used in the MGB’s are no-longer available at any service stations I also order some some from the MG Owners Club (http://www.mgocspares.co.uk/).

While picking up the car the previous owner also noticed that one of the side lights had stopped working during their journey to the Airport. While checking this I also gave the car a quick check over to see if anything else was in need of immediate replacement prior to starting on the bodywork.

While checking the lights I found that the housing for the driver side headlamp was severely corroded, and some of the wires (namely the side light ones), had came away from their terminal connectors.

I added the headlamp housing and rubber seal to the list of parts I needed just now.

The delivery of the spares was very prompt, allowing me to replace the parts over the next few weekends, taking a few weekends off to visit relatives over Christmas and getting the car running again last weekend.


Having replaced all but the ignition coil and distributor itself, the engine appears to be running smoothly now, though I have only ran it for 5 to 10 miles so far, I intend run it a bit more before starting to strip out more major parts for inspection, and possible replacement.

Some of the things that are on my list to tackle next include: –

  • One of the jack points needs re-welded (will also get a mechanic to check and see if any other welding is required)
  • Some areas need to be retreated with under-seal
  • Driver side sill, to the rear, needs repaired
  • The major job… the various areas of bodywork that need attention and a re-spray
  • General engine bay tidy up (some water trap areas need touching up and repairing)
  • Source problem with de-mist pipes and manual water jets
  • Locate where cold air is entering the foot-well (cool air vent was shut)
  • Look into the heater and all associated piping (air and water), see what needs replaced and what is OK
  • Fitting electric water jets (still fitted with the old manual jets)
  • Window seals (front quarter windows in particular) need attention
  • Oil change and replace oil filter
  • Check header gasket and possibly replace
  • Re-oil SU carburetors
  • Replace timing belt (as I have no idea when it was last done) 

              … no doubt more will be added to the list as the project unfolds …

For it’s age and the money I parted with, I am quite pleased with the condition of the car so far… particularly given the previous owner had told me that the owner, prior to them, had left it sitting outdoors unused for many years (to the point it was moss covered), before they rescued it. They gave it a little clean up and continued using it for a couple of years as a general run around until they had to sell to it to make way for a VW Camper they were purchasing.

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