I’m in the proces of finetuning the 140 and working on the carbs now.
I use a synchrometer for flow and a gunson “glass” sparkplug to determine how rich/lean the mixture is while running. I also check the plug colour after each adjustment run.
The engine is equipped with a “type C “ head, pancake aircleaners. CR is 8:1. Carbs are H6, The needles used are WO2 and according to the literature those are the correct ones.
These are my findings until now:
At first the sparkplugs where deep black… my conclusion: too rich.
In four steps i tried to lean out the car while checking the plugcolour and with help of the “glass plug” the colour of the combustion running idle.
At this point the jets are in the highest position.
- According to the combustion colour (not as yellow as it was but still not blue) it is leaning out but running still (a bit) rich. Combustion colour in nr 1 cyl is about the same as in nr 6 cyl.
- According to the spark plugs, the porcelain bit is getting brownish black. the metal bit is getting less black. All 6 plugs showing more or less the same colour.
I concider trying different needles but would like your opinion.