With a load of documents, high hopes, and a lot of sunshine I headed to a technical inspection with the MGB last week. Back in September/October last year I did a full service on Maggie just before taking her out on the last longer drive (approx. 500km) for the year. Since then, we just occasionally used the car when the weather was good. But as usually, the GT started up fine and the engine ran smoothly as ever for the first ~50km to the DEKRA office. But while accelerating to 120km/h I suddenly had a misfire. Over the next few kilometers this became worse. As soon as the rpm went above 2000 the engine was not running smooth and lacked the normal power.
The document check for a planned changes in my car papers showed that I still need further documents/certifications for 2 of 5 changes. I got a good explanation on what I need and hints on where to get the required “ABE” (German abbreviation for Allgemeine BetriebsErlaubnis) for one part.
The 50km back to my garage took longer as the problems and misfires increased, but somehow, I was able to get back to my garage. My first check were the spark plugs. And the result was a bit unexpected. Cylinder 2 & 3 looked good – 1 & 4 too dark/rich. This is strange because the Weber45DCOE on my car and the inlets of the cylinder-head are for cylinder 1 & 2 and 3 & 4.
Therefore, I concluded that it is most likely not a fuel/carburetor related problem. Nevertheless, I checked that the fuel pressure is good – which it was with just over 3 psi. I also ordered a new insert for the Malpassi Filter King fuel filter. The jets on the Weber are completely clean – the K&N air filter will also be cleaned this weekend.
So,my attentention shifted to the distributor. My car has a CSI Standard 25D4 – which is just 4 years/18800km old. The distributor cap and rotor look like new. I know that it has pre-programmable curves – but I don’t have any documentation for it. I filled out the form on the CSI website and got a fast reply with the necessary information on how to read the current setting as well as diagrams for the curves. All I could do was to check static timing and this was set up 12° – just as advised by Frontline when I picked up the car.
A compression test showed values between 175 and a bit over 180psi – which is good. Next I checked valve clearance again. To my surprise the outlet valves on cyl 1 and 4 (valve 1 and 8) had almost on play at all. On my last inspection this was fine and 14thou (0.35mm). After this correction the engine runs much better again. This raises the question: what can cause a sudden loss of valve clearance? Maybe the head gasket? Double-checking the torque (65nm) on the cylinder-head nuts? And the compression test was good.
This leaves the following options in my opinion (maybe there are more – post a comment if you have an idea). A) there is an issue with the valve seats. B) there is an issue with the rocker c) I made a measuring mistake.
Human error (ok – my error to be precise) is usually the most likely. But I triple checked by now and believe to have done it correctly. The best way forward was to consult experts. Luckily, I was able to get an appointment at Viktor Günther Motorsport in Cologne. They will do all checks again, as well as a pressure-loss check. In addition they willbinstall a CSI professional distributor and find the best ignition curve on a rolling road.
Before I dropped off the MGB in Cologne I was able to get the necessary documents and passed the technical inspection of my suspension. The only thing the tester found was a new oil leak. And kindly enough he pointed out the issue. The copper washer/deal between the oil pressure hose and engine failed. Kischka in Cologne had the required spares – it is a bit fiddly to fasten it with the distributor in place but 10min later the problem was solved.
My trip up North to visit my parents this weekend had to be done with Miffi – my Mini. But when checking and preparing the car for the trip (approx 900km in total) – I noticed that the hinges are broken. I would have preferred hinges in the cars color – but the chrome variant was easier to get. Hopefully, Miffi is not going to break down on me on my way home… My father’s wheel chair battery only lasts for 19km 😜
Fixing C6622 
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