Setting Cold Control Pressures under 10 Degrees
 

All the CIS charts go from 10C to 40C. For a warmed up engine, say on a 79, we always use the 40C figure, 3.2-3.6 bar, w/ vac line attached.

If we want to set the cold cp @ a temp less than 10C , say 0C, do we use the 10C figure, which is 1.2-1.6, or should we extrapolate downward to about .5 to 1 bar, which is what the chart would read if it were extended to that degree?

Has anyone ever observed their cold cp @ less than 10C? What cp did you get?

Or set up their cold cp when the engine was less than 10C? What cp did you use?

I have always used the ambient temperature on a cold engine. Let the car sit over night and then play with the pressures the next day. I would have to guess that the temperature window on the graphs provide the most consistent results. Still cold up there, eh?

It's not too bad, Ron--about 10C today and 13C tomorrow.

I understand what you are saying. I'm having difficulty expressing myself here. If I get a ccp reading that is "on the chart" when the temp is "on the chart" thats fine. But let's say the temps drop to 0C next week and I'm setting up the CPs. Do I use the lowest setting (which is for 10) or knock the plug even farther down to get a lower figure?

Ty is set up @ .8 bar which is about 1 bar below the 10C figure and yet his temps are probably seldom lower than 0C.

If a ccp is within the spec for 10C will it be lower if a reading is taken @ 0C? Or will it always be the figure for 10 no matter how much lower the temp goes?