Gunson Colourtune

C

cfcrotweiller

Member
Afternoon gents,

I have tried out the Gunson Colourtune yesterday with variable success.

I thought that turning the nut on the HS6 carb mixture would change the colour of the ignition quite quickly, but I am able to turn the nut probably nearly one full turn before I see a slight difference in ignition colour.
Is this normal? I was hoping to see a big difference with little movement to get it finely tuned.

Thanks
Andy
 
It could have just been very lean/rich to begin with.
When you are near the sweet spot the colour should change with minimal movement.
My HIF carbs were tuned VERY lean when I first checked them and it took a lot of adjustment to get them near.
Once I was in the ballpark though, I could fine tune them.
I don't know how much difference it would make if your carbs were very leaky, leaning out the mixture?
Jim
 
corazon said:
It could have just been very lean/rich to begin with.
When you are near the sweet spot the colour should change with minimal movement.
My HIF carbs were tuned VERY lean when I first checked them and it took a lot of adjustment to get them near.
Once I was in the ballpark though, I could fine tune them.
I don't know how much difference it would make if your carbs were very leaky, leaning out the mixture?
Jim
Click to expand...


The carbs may need servicing yes.
One thing I read on a HS6 carb website was how to get the mixture ball park.
Screw the mixture nut in until the nozzle inside the carb is flush with the surface. Then 12 flat screws out. This is what I did, so I'm hoping its not far off.
When using the Gunson however I noticed the two plugs I removed were black with soot. Im guessing too rich. The good thing is leaning the nut did change the colour to blue but it wasnt my any means a sudden change, took a a good few turns of the nut before it changed.

Then again, the car has been stood for 30 years and has only ran in the past month but still gathering parts together, the manifold/carbs were off another car so I have to assume it's going to need a real tweaking, experimenting, re tweaking again.
 
The transition from Blue to Orange on the colourtune can tke a number of flats of the mixture nut. You are looking for the moment that the first orange flecks appear in the blue. I'd suggest getting this by moving from weak towards rich.

Chris
 
chrisyork said:
The transition from Blue to Orange on the colourtune can tke a number of flats of the mixture nut. You are looking for the moment that the first orange flecks appear in the blue. I'd suggest getting this by moving from weak towards rich.

Chris
Click to expand...


Chris, thanks for that. I think I will try that then. I will reset the carbs to the lean mixture and basically richen it out until the blue flame begins to show the slightest of orange hint to it.
Although I truly believe in doing it by ear, I sometimes doubt whether its right or not. But I definitely notice the engine is not smooth yet. So there is some improvement to be had.
 
I've used and sold Colortunes for years,I believe the newer fuels affect the results obtained with them.Oil in the fuel (two strokes) and methanol mix etc alters the combustion colour and I believe the ethanol and other chemicals added does too.
It's also a good idea to blip the throttle every so often to clear the intake passages (the earlier Colortunes were suitable for very low revs only).
 
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