[ROVERNET - UK] Mixture problems

[Steven Dibdin]

Hi Rover Gurus,

I've recently fitted a petronix ignition system to my '68 2000 TC along with 
their 'flamethrower' coil (god awful name by the way). Timing is spot on, I 
had to replace the old worn out advance weight springs as they were weak 
with age. I have checked the advance curve with a strobe light and tacho 
against the specs for my engine (10:1 compression) and that is as it should.

My problem is that the fuel mixture seems to be off now. If I set the carbs' 
at idle using the workshop manual method of lifting the pins and getting the 
idle to rise then fall it runs a little rough at idle, after a few minutes 
of running the plugs get sooted up. Suggesting it's too rich at idle. On the 
road however, it runs far better than before, better acceleration, more 
responsive and a smoother delivery of power.

If I adjust the mixture at idle using my colourtune the idle pretty smooth 
but it is running too lean on the road, power's lacking until I pull out the 
choke to enrich the mixture.

So my questions are: Has anyone else found a similar problem after changing 
over to Petronix? Did they go for different needle profiles to accommodate 
the new system? Do I need to find a rolling road to tune with new needles 
now?

Anybody out there have any suggestions?

Many thanks,

Steven Dibdin