I fitted my 123 over the weekend, along with coil, HT leads, and fuel pump. She ran absolutely brilliantly on the test run right up to when she didn't and had to be rescued by the AA from the M3. It's an intermittent fault and so I'm putting back all the old kit, cleaning the carbs and starting again!
It didn't work. Well, it works but misfire still there. Changed leads Changed plugs Changed distributor Changed exhaust Checked valve clearances Wtf else is there unless it's carbs?
after I'd done the rings on my 2ltr engine I thought id done something wrong as I had the exact same problem. kept getting a phut phut every so often but no pattern to it. I found that one of the sealing rings between the head and the heat exchanger wasnt seating properly. took the heat exchanger off and blobbed on some exhaust paste and it sealed properly. I was getting the odd bang and fart on over run too