Morris Minor Owners Club

Good Lord!!

Tuned the mixture a flat leaner. Took the Moggy for 10km cruising run. Great ride and noticeable power increase. Overtook couple of Ashok Leyland buses

Realizing that I've been running on just three cylinders all this time blaming it on the engine and perhaps thinking that the timing was too retarded. Only now I'm experiencing the true power of 948cc BMC A series engine .

2016 seems to have started showing prosperity..

Thinking of inspecting the plugs after a while for the so called "biscuit tan"

I wouldn't suspect the piston rings / bore right now unless the new plug in cylinder 4 gives up again after a while under the new mixture setting. Probably a dodgy plug running on a rich mixture caused all the trouble.

Get rid of the useless Colortune..... Get a very useful Compression Tester instead.

Ran another 27 kms and so far so good...!! Seems problem is solved. Thanks all for all the helpful suggestions.

Hmmm.. bmc, I sure need to invest in a compression tester.

Well the colortune made life easier in my case as opposed to the lifting of the piston and the whole lot of subjective perception that follows to get the engine tuned as per the workshop manual.

Hi Guys Rob – My side valve motor is supercharged at a bit over 1.1.bar. When the disy curve was mapped and the carb needle selected the guy tuning the motor was not able to stop preignition or pinking at high outputs. I had previously done research and found that with highly blown or tuned motors this knocking could occur due to the fact that the spark plug earth electrode may glow red hot pre_igniting the incoming mixture. Because of this I bought a set of NGK BU8H plugs which are surface discharge plugs and a range colder than standard with no earth electrode. When fitted they completely eliminated the knocking and allowed my tuning man to continue to advance the timing and get good results. Because they are surface discharge plugs the gap is not variable but fixed at 1.5 mm. (0.060”). I am using a Lucas GT 40 coil and after about 2600 miles on the plugs without having been touched they are performing perfectly even up to 7500 RPM. The disy is a 23D4 from a Mk. 1 Cooper with conventional points. This comparatively high non variable plug gap supports your theory of the coil voltage rising to jump the largest gap presented to it.
Cheers Bob